Pianotech

In a recent discussion with a colleague I was conveying my method of determining bridge cap thickness in advance of gluing on the new cap material.  This way I can plane the new cap to the proper thickness before gluing it on.  I find that easier, and more accurate, than the traditional method of gluing on an oversize (thickness) cap and then cutting slots in the top and then planing the bridge to the depth of those slots. 

The pictures below are pretty self-explanatory.  I've sent a suggestion to Mazzaglia that they produce something like this out of brass, like their other fine tools.  But you can make one of these out of wood easily enough.  I actually found a metal wedge on line which was exactly these dimension that I use for this purpose, adding the markings myself.  The width of the wedge corresponds to the average spacing between the bridge pins.   

Here's a link to the item I purchased recently after my original wooden wedge that I had made got damaged.  Bueyfolt 1/2" x 3/4" x 4" Flange Wedge, Zinc Plated Metal Flange Wedge Pipe Fitting Welding Tool, Strong Welding Wedge, Rust-Proof, Corrosion Resistant and Strong, Spreading Flanges Triangle Tool - Amazon.com 

Procedurally, you determine the distance bearing at the rear string rest by multiplying the length of the backscale by .0175 for each 1 degree of distance bearing that you want (.0175 is the sine of 1 degree).  I then use the Mazzaglia bearing gauges set on top of the rear string rest and lower the string until it rests on the gauge/string rest and then slide the wedge under the string until it just touches the string.  Read the thickness and that's the bridge cap thickness.  By adding the cap thickness to the bridge root height it will give you how high the top of the cap should be above the SB.  I then write in pencil directly on the SB at that point the target height of the bridge with the cap.  I then plane the cap material to that target plus 1 mm and sand the cap to the final height.  Lay out the bridge pin array and go from there. 

I always pre-stress the board by inserting some wedges under the struts of the piano to "take out the slack" before I take the measurements.  .  

In a recent discussion with a colleague I was conveying my method of determining bridge cap thickness in advance of gluing on the new cap material.  This way I can plane the new cap to the proper thickness before gluing it on.  I find that easier, and more accurate, than the traditional method of gluing on an oversize (thickness) cap and then cutting slots in the top and then planing the bridge to the depth of those slots. 

The pictures below are pretty self-explanatory.  I've sent a suggestion to Mazzaglia that they produce something like this out of brass, like their other fine tools.  But you can make one of these out of wood easily enough.  I actually found a metal wedge on line which was exactly these dimension that I use for this purpose, adding the markings myself.  The width of the wedge corresponds to the average spacing between the bridge pins.   

Here's a link to the item I purchased recently after my original wooden wedge that I had made got damaged.  Bueyfolt 1/2" x 3/4" x 4" Flange Wedge, Zinc Plated Metal Flange Wedge Pipe Fitting Welding Tool, Strong Welding Wedge, Rust-Proof, Corrosion Resistant and Strong, Spreading Flanges Triangle Tool - Amazon.com 

Procedurally, you determine the distance bearing at the rear string rest by multiplying the length of the backscale by .0175 for each 1 degree of distance bearing that you want (.0175 is the sine of 1 degree).  I then use the Mazzaglia bearing gauges set on top of the rear string rest and lower the string until it rests on the gauge/string rest and then slide the wedge under the string until it just touches the string.  Read the thickness and that's the bridge cap thickness.  By adding the cap thickness to the bridge root height it will give you how high the top of the cap should be above the SB.  I then write in pencil directly on the SB at that point the target height of the bridge with the cap.  I then plane the cap material to that target plus 1 mm and sand the cap to the final height.  Lay out the bridge pin array and go from there. 

I always pre-stress the board by inserting some wedges under the struts of the piano to "take out the slack" before I take the measurements.  .  

In a recent discussion with a colleague I was conveying my method of determining bridge cap thickness in advance of gluing on the new cap material.  This way I can plane the new cap to the proper thickness before gluing it on.  I find that easier, and more accurate, than the traditional method of gluing on an oversize (thickness) cap and then cutting slots in the top and then planing the bridge to the depth of those slots. 

The pictures below are pretty self-explanatory.  I've sent a suggestion to Mazzaglia that they produce something like this out of brass, like their other fine tools.  But you can make one of these out of wood easily enough.  I actually found a metal wedge on line which was exactly these dimension that I use for this purpose, adding the markings myself.  The width of the wedge corresponds to the average spacing between the bridge pins.   

Here's a link to the item I purchased recently after my original wooden wedge that I had made got damaged.  Bueyfolt 1/2" x 3/4" x 4" Flange Wedge, Zinc Plated Metal Flange Wedge Pipe Fitting Welding Tool, Strong Welding Wedge, Rust-Proof, Corrosion Resistant and Strong, Spreading Flanges Triangle Tool - Amazon.com 

Procedurally, you determine the distance bearing at the rear string rest by multiplying the length of the backscale by .0175 for each 1 degree of distance bearing that you want (.0175 is the sine of 1 degree).  I then use the Mazzaglia bearing gauges set on top of the rear string rest and lower the string until it rests on the gauge/string rest and then slide the wedge under the string until it just touches the string.  Read the thickness and that's the bridge cap thickness.  By adding the cap thickness to the bridge root height it will give you how high the top of the cap should be above the SB.  I then write in pencil directly on the SB at that point the target height of the bridge with the cap.  I then plane the cap material to that target plus 1 mm and sand the cap to the final height.  Lay out the bridge pin array and go from there. 

I always pre-stress the board by inserting some wedges under the struts of the piano to "take out the slack" before I take the measurements.  .  

In a recent discussion with a colleague I was conveying my method of determining bridge cap thickness in advance of gluing on the new cap material.  This way I can plane the new cap to the proper thickness before gluing it on.  I find that easier, and more accurate, than the traditional method of gluing on an oversize (thickness) cap and then cutting slots in the top and then planing the bridge to the depth of those slots. 

The pictures below are pretty self-explanatory.  I've sent a suggestion to Mazzaglia that they produce something like this out of brass, like their other fine tools.  But you can make one of these out of wood easily enough.  I actually found a metal wedge on line which was exactly these dimension that I use for this purpose, adding the markings myself.  The width of the wedge corresponds to the average spacing between the bridge pins.   

Here's a link to the item I purchased recently after my original wooden wedge that I had made got damaged.  Bueyfolt 1/2" x 3/4" x 4" Flange Wedge, Zinc Plated Metal Flange Wedge Pipe Fitting Welding Tool, Strong Welding Wedge, Rust-Proof, Corrosion Resistant and Strong, Spreading Flanges Triangle Tool - Amazon.com 

Procedurally, you determine the distance bearing at the rear string rest by multiplying the length of the backscale by .0175 for each 1 degree of distance bearing that you want (.0175 is the sine of 1 degree).  I then use the Mazzaglia bearing gauges set on top of the rear string rest and lower the string until it rests on the gauge/string rest and then slide the wedge under the string until it just touches the string.  Read the thickness and that's the bridge cap thickness.  By adding the cap thickness to the bridge root height it will give you how high the top of the cap should be above the SB.  I then write in pencil directly on the SB at that point the target height of the bridge with the cap.  I then plane the cap material to that target plus 1 mm and sand the cap to the final height.  Lay out the bridge pin array and go from there. 

I always pre-stress the board by inserting some wedges under the struts of the piano to "take out the slack" before I take the measurements.  .  

In a recent discussion with a colleague I was conveying my method of determining bridge cap thickness in advance of gluing on the new cap material.  This way I can plane the new cap to the proper thickness before gluing it on.  I find that easier, and more accurate, than the traditional method of gluing on an oversize (thickness) cap and then cutting slots in the top and then planing the bridge to the depth of those slots. 

The pictures below are pretty self-explanatory.  I've sent a suggestion to Mazzaglia that they produce something like this out of brass, like their other fine tools.  But you can make one of these out of wood easily enough.  I actually found a metal wedge on line which was exactly these dimension that I use for this purpose, adding the markings myself.  The width of the wedge corresponds to the average spacing between the bridge pins.   

Here's a link to the item I purchased recently after my original wooden wedge that I had made got damaged.  Bueyfolt 1/2" x 3/4" x 4" Flange Wedge, Zinc Plated Metal Flange Wedge Pipe Fitting Welding Tool, Strong Welding Wedge, Rust-Proof, Corrosion Resistant and Strong, Spreading Flanges Triangle Tool - Amazon.com 

Procedurally, you determine the distance bearing at the rear string rest by multiplying the length of the backscale by .0175 for each 1 degree of distance bearing that you want (.0175 is the sine of 1 degree).  I then use the Mazzaglia bearing gauges set on top of the rear string rest and lower the string until it rests on the gauge/string rest and then slide the wedge under the string until it just touches the string.  Read the thickness and that's the bridge cap thickness.  By adding the cap thickness to the bridge root height it will give you how high the top of the cap should be above the SB.  I then write in pencil directly on the SB at that point the target height of the bridge with the cap.  I then plane the cap material to that target plus 1 mm and sand the cap to the final height.  Lay out the bridge pin array and go from there. 

I always pre-stress the board by inserting some wedges under the struts of the piano to "take out the slack" before I take the measurements.  .  

In a recent discussion with a colleague I was conveying my method of determining bridge cap thickness in advance of gluing on the new cap material.  This way I can plane the new cap to the proper thickness before gluing it on.  I find that easier, and more accurate, than the traditional method of gluing on an oversize (thickness) cap and then cutting slots in the top and then planing the bridge to the depth of those slots. 

The pictures below are pretty self-explanatory.  I've sent a suggestion to Mazzaglia that they produce something like this out of brass, like their other fine tools.  But you can make one of these out of wood easily enough.  I actually found a metal wedge on line which was exactly these dimension that I use for this purpose, adding the markings myself.  The width of the wedge corresponds to the average spacing between the bridge pins.   

Here's a link to the item I purchased recently after my original wooden wedge that I had made got damaged.  Bueyfolt 1/2" x 3/4" x 4" Flange Wedge, Zinc Plated Metal Flange Wedge Pipe Fitting Welding Tool, Strong Welding Wedge, Rust-Proof, Corrosion Resistant and Strong, Spreading Flanges Triangle Tool - Amazon.com 

Procedurally, you determine the distance bearing at the rear string rest by multiplying the length of the backscale by .0175 for each 1 degree of distance bearing that you want (.0175 is the sine of 1 degree).  I then use the Mazzaglia bearing gauges set on top of the rear string rest and lower the string until it rests on the gauge/string rest and then slide the wedge under the string until it just touches the string.  Read the thickness and that's the bridge cap thickness.  By adding the cap thickness to the bridge root height it will give you how high the top of the cap should be above the SB.  I then write in pencil directly on the SB at that point the target height of the bridge with the cap.  I then plane the cap material to that target plus 1 mm and sand the cap to the final height.  Lay out the bridge pin array and go from there. 

I always pre-stress the board by inserting some wedges under the struts of the piano to "take out the slack" before I take the measurements.  .  

Terry Farrell (Post #4),

In my opinion (and what do I know, really), a Steinway bridge root/trunk (as one example) is made to the "ideal" height at the factory. This vertically laminated member is strong/unyielding in its original height from end to end, with a cap glued atop that is just tall enough to accommodate the deepest union notches. If we reduce the root to accommodate a thicker cap, we weaken it. The cap material is flexible in its linear dimension; the bridge root is not, and there's a reason for that. The root supports the crown along the grain of the soundboard for the life of the instrument. In my rebuilding work, and again what the heck do I know, I never violated the height of the root. I was much happier "wasting" cap material than reducing the root. I know you use a vertically laminated cap, and perhaps this makes up for the loss (but you have introduced a glue joint that never existed at that elevation, and the root structure would be stronger without it, with continuous vertical grain top-to-bottom, methinks), but I have seen scads of rebuilt Steinway and Mason & Hamlin pianos over the last 45 years with significantly reduced roots and chunky quartersawn maple caps, and they distress me.

David G. Hughes, RPT

Baltimore Chapter

In a recent discussion with a colleague I was conveying my method of determining bridge cap thickness in advance of gluing on the new cap material.  This way I can plane the new cap to the proper thickness before gluing it on.  I find that easier, and more accurate, than the traditional method of gluing on an oversize (thickness) cap and then cutting slots in the top and then planing the bridge to the depth of those slots. 

The pictures below are pretty self-explanatory.  I've sent a suggestion to Mazzaglia that they produce something like this out of brass, like their other fine tools.  But you can make one of these out of wood easily enough.  I actually found a metal wedge on line which was exactly these dimension that I use for this purpose, adding the markings myself.  The width of the wedge corresponds to the average spacing between the bridge pins.   

Here's a link to the item I purchased recently after my original wooden wedge that I had made got damaged.  Bueyfolt 1/2" x 3/4" x 4" Flange Wedge, Zinc Plated Metal Flange Wedge Pipe Fitting Welding Tool, Strong Welding Wedge, Rust-Proof, Corrosion Resistant and Strong, Spreading Flanges Triangle Tool - Amazon.com 

Procedurally, you determine the distance bearing at the rear string rest by multiplying the length of the backscale by .0175 for each 1 degree of distance bearing that you want (.0175 is the sine of 1 degree).  I then use the Mazzaglia bearing gauges set on top of the rear string rest and lower the string until it rests on the gauge/string rest and then slide the wedge under the string until it just touches the string.  Read the thickness and that's the bridge cap thickness.  By adding the cap thickness to the bridge root height it will give you how high the top of the cap should be above the SB.  I then write in pencil directly on the SB at that point the target height of the bridge with the cap.  I then plane the cap material to that target plus 1 mm and sand the cap to the final height.  Lay out the bridge pin array and go from there. 

I always pre-stress the board by inserting some wedges under the struts of the piano to "take out the slack" before I take the measurements.  .  

I know very little about bellyman work, but I know that the net outcome of the bridge downbearing is essential to the sound quality: volume, sustain, thinness/weakness, tone, etc with particular sensitivity in the treble. A certain number of the rebuilt grands that I come across, in homes and in stores, have portions of their treble with deficiencies in sound. If I am right in this observation, then what is the probability of success for a typical rebuild?

Your post, David, seems straight-forward for setting the downbearing (in an overall complex process!) before beginning to restring. Is the object to achieve an equal downbearing across the whole scale when you are done restringing, as measured by angle? Or if, as I assume, the (real) target is equality as measured by string downward pressure/force, how many pounds per string do you target for? 

Finally, I have the impression that the physical downbearing (of strings pushing on the bridges) is non-linear across the complete scale. If this is the case, do you somehow have to pre-load against the bridges (when shaping the bridges) to garner your desired downbearing end result after restringing?

Regards, Norman. 

Terry Farrell (Post #4),

In my opinion (and what do I know, really), a Steinway bridge root/trunk (as one example) is made to the "ideal" height at the factory. This vertically laminated member is strong/unyielding in its original height from end to end, with a cap glued atop that is just tall enough to accommodate the deepest union notches. If we reduce the root to accommodate a thicker cap, we weaken it. The cap material is flexible in its linear dimension; the bridge root is not, and there's a reason for that. The root supports the crown along the grain of the soundboard for the life of the instrument. In my rebuilding work, and again what the heck do I know, I never violated the height of the root. I was much happier "wasting" cap material than reducing the root. I know you use a vertically laminated cap, and perhaps this makes up for the loss (but you have introduced a glue joint that never existed at that elevation, and the root structure would be stronger without it, with continuous vertical grain top-to-bottom, methinks), but I have seen scads of rebuilt Steinway and Mason & Hamlin pianos over the last 45 years with significantly reduced roots and chunky quartersawn maple caps, and they distress me.

David G. Hughes, RPT

Baltimore Chapter

In a recent discussion with a colleague I was conveying my method of determining bridge cap thickness in advance of gluing on the new cap material.  This way I can plane the new cap to the proper thickness before gluing it on.  I find that easier, and more accurate, than the traditional method of gluing on an oversize (thickness) cap and then cutting slots in the top and then planing the bridge to the depth of those slots. 

The pictures below are pretty self-explanatory.  I've sent a suggestion to Mazzaglia that they produce something like this out of brass, like their other fine tools.  But you can make one of these out of wood easily enough.  I actually found a metal wedge on line which was exactly these dimension that I use for this purpose, adding the markings myself.  The width of the wedge corresponds to the average spacing between the bridge pins.   

Here's a link to the item I purchased recently after my original wooden wedge that I had made got damaged.  Bueyfolt 1/2" x 3/4" x 4" Flange Wedge, Zinc Plated Metal Flange Wedge Pipe Fitting Welding Tool, Strong Welding Wedge, Rust-Proof, Corrosion Resistant and Strong, Spreading Flanges Triangle Tool - Amazon.com 

Procedurally, you determine the distance bearing at the rear string rest by multiplying the length of the backscale by .0175 for each 1 degree of distance bearing that you want (.0175 is the sine of 1 degree).  I then use the Mazzaglia bearing gauges set on top of the rear string rest and lower the string until it rests on the gauge/string rest and then slide the wedge under the string until it just touches the string.  Read the thickness and that's the bridge cap thickness.  By adding the cap thickness to the bridge root height it will give you how high the top of the cap should be above the SB.  I then write in pencil directly on the SB at that point the target height of the bridge with the cap.  I then plane the cap material to that target plus 1 mm and sand the cap to the final height.  Lay out the bridge pin array and go from there. 

I always pre-stress the board by inserting some wedges under the struts of the piano to "take out the slack" before I take the measurements.  .  

The bridges participation of the tonal characteristic can easily be underestimated. Years ago i visited the shop of another technician struggling with this very issue. It was a 7' Chickering I believe with a very narrow bridge for a piano that size. The technician had lowered the tension of the strings, and removed all of the coils off the pins, removed the strings off the bridges, and had the plate up in the air. When i walked in he was adding a bridge boot for stiffness and mass. I remember thinking at the time that just listening to the piano before tear down probably would have save a lot of time. So he was dealing with too open a sound. The opposite happens with too much stiffness, That's why i never use laminated caps and stay close to the original design.

-chris

I know very little about bellyman work, but I know that the net outcome of the bridge downbearing is essential to the sound quality: volume, sustain, thinness/weakness, tone, etc with particular sensitivity in the treble. A certain number of the rebuilt grands that I come across, in homes and in stores, have portions of their treble with deficiencies in sound. If I am right in this observation, then what is the probability of success for a typical rebuild?

Your post, David, seems straight-forward for setting the downbearing (in an overall complex process!) before beginning to restring. Is the object to achieve an equal downbearing across the whole scale when you are done restringing, as measured by angle? Or if, as I assume, the (real) target is equality as measured by string downward pressure/force, how many pounds per string do you target for? 

Finally, I have the impression that the physical downbearing (of strings pushing on the bridges) is non-linear across the complete scale. If this is the case, do you somehow have to pre-load against the bridges (when shaping the bridges) to garner your desired downbearing end result after restringing?

Regards, Norman. 

Terry Farrell (Post #4),

In my opinion (and what do I know, really), a Steinway bridge root/trunk (as one example) is made to the "ideal" height at the factory. This vertically laminated member is strong/unyielding in its original height from end to end, with a cap glued atop that is just tall enough to accommodate the deepest union notches. If we reduce the root to accommodate a thicker cap, we weaken it. The cap material is flexible in its linear dimension; the bridge root is not, and there's a reason for that. The root supports the crown along the grain of the soundboard for the life of the instrument. In my rebuilding work, and again what the heck do I know, I never violated the height of the root. I was much happier "wasting" cap material than reducing the root. I know you use a vertically laminated cap, and perhaps this makes up for the loss (but you have introduced a glue joint that never existed at that elevation, and the root structure would be stronger without it, with continuous vertical grain top-to-bottom, methinks), but I have seen scads of rebuilt Steinway and Mason & Hamlin pianos over the last 45 years with significantly reduced roots and chunky quartersawn maple caps, and they distress me.

David G. Hughes, RPT

Baltimore Chapter

In a recent discussion with a colleague I was conveying my method of determining bridge cap thickness in advance of gluing on the new cap material.  This way I can plane the new cap to the proper thickness before gluing it on.  I find that easier, and more accurate, than the traditional method of gluing on an oversize (thickness) cap and then cutting slots in the top and then planing the bridge to the depth of those slots. 

The pictures below are pretty self-explanatory.  I've sent a suggestion to Mazzaglia that they produce something like this out of brass, like their other fine tools.  But you can make one of these out of wood easily enough.  I actually found a metal wedge on line which was exactly these dimension that I use for this purpose, adding the markings myself.  The width of the wedge corresponds to the average spacing between the bridge pins.   

Here's a link to the item I purchased recently after my original wooden wedge that I had made got damaged.  Bueyfolt 1/2" x 3/4" x 4" Flange Wedge, Zinc Plated Metal Flange Wedge Pipe Fitting Welding Tool, Strong Welding Wedge, Rust-Proof, Corrosion Resistant and Strong, Spreading Flanges Triangle Tool - Amazon.com 

Procedurally, you determine the distance bearing at the rear string rest by multiplying the length of the backscale by .0175 for each 1 degree of distance bearing that you want (.0175 is the sine of 1 degree).  I then use the Mazzaglia bearing gauges set on top of the rear string rest and lower the string until it rests on the gauge/string rest and then slide the wedge under the string until it just touches the string.  Read the thickness and that's the bridge cap thickness.  By adding the cap thickness to the bridge root height it will give you how high the top of the cap should be above the SB.  I then write in pencil directly on the SB at that point the target height of the bridge with the cap.  I then plane the cap material to that target plus 1 mm and sand the cap to the final height.  Lay out the bridge pin array and go from there. 

I always pre-stress the board by inserting some wedges under the struts of the piano to "take out the slack" before I take the measurements.  .  

I know very little about bellyman work, but I know that the net outcome of the bridge downbearing is essential to the sound quality: volume, sustain, thinness/weakness, tone, etc with particular sensitivity in the treble. A certain number of the rebuilt grands that I come across, in homes and in stores, have portions of their treble with deficiencies in sound. If I am right in this observation, then what is the probability of success for a typical rebuild?

Your post, David, seems straight-forward for setting the downbearing (in an overall complex process!) before beginning to restring. Is the object to achieve an equal downbearing across the whole scale when you are done restringing, as measured by angle? Or if, as I assume, the (real) target is equality as measured by string downward pressure/force, how many pounds per string do you target for? 

Finally, I have the impression that the physical downbearing (of strings pushing on the bridges) is non-linear across the complete scale. If this is the case, do you somehow have to pre-load against the bridges (when shaping the bridges) to garner your desired downbearing end result after restringing?

Regards, Norman. 

Terry Farrell (Post #4),

In my opinion (and what do I know, really), a Steinway bridge root/trunk (as one example) is made to the "ideal" height at the factory. This vertically laminated member is strong/unyielding in its original height from end to end, with a cap glued atop that is just tall enough to accommodate the deepest union notches. If we reduce the root to accommodate a thicker cap, we weaken it. The cap material is flexible in its linear dimension; the bridge root is not, and there's a reason for that. The root supports the crown along the grain of the soundboard for the life of the instrument. In my rebuilding work, and again what the heck do I know, I never violated the height of the root. I was much happier "wasting" cap material than reducing the root. I know you use a vertically laminated cap, and perhaps this makes up for the loss (but you have introduced a glue joint that never existed at that elevation, and the root structure would be stronger without it, with continuous vertical grain top-to-bottom, methinks), but I have seen scads of rebuilt Steinway and Mason & Hamlin pianos over the last 45 years with significantly reduced roots and chunky quartersawn maple caps, and they distress me.

David G. Hughes, RPT

Baltimore Chapter

In a recent discussion with a colleague I was conveying my method of determining bridge cap thickness in advance of gluing on the new cap material.  This way I can plane the new cap to the proper thickness before gluing it on.  I find that easier, and more accurate, than the traditional method of gluing on an oversize (thickness) cap and then cutting slots in the top and then planing the bridge to the depth of those slots. 

The pictures below are pretty self-explanatory.  I've sent a suggestion to Mazzaglia that they produce something like this out of brass, like their other fine tools.  But you can make one of these out of wood easily enough.  I actually found a metal wedge on line which was exactly these dimension that I use for this purpose, adding the markings myself.  The width of the wedge corresponds to the average spacing between the bridge pins.   

Here's a link to the item I purchased recently after my original wooden wedge that I had made got damaged.  Bueyfolt 1/2" x 3/4" x 4" Flange Wedge, Zinc Plated Metal Flange Wedge Pipe Fitting Welding Tool, Strong Welding Wedge, Rust-Proof, Corrosion Resistant and Strong, Spreading Flanges Triangle Tool - Amazon.com 

Procedurally, you determine the distance bearing at the rear string rest by multiplying the length of the backscale by .0175 for each 1 degree of distance bearing that you want (.0175 is the sine of 1 degree).  I then use the Mazzaglia bearing gauges set on top of the rear string rest and lower the string until it rests on the gauge/string rest and then slide the wedge under the string until it just touches the string.  Read the thickness and that's the bridge cap thickness.  By adding the cap thickness to the bridge root height it will give you how high the top of the cap should be above the SB.  I then write in pencil directly on the SB at that point the target height of the bridge with the cap.  I then plane the cap material to that target plus 1 mm and sand the cap to the final height.  Lay out the bridge pin array and go from there. 

I always pre-stress the board by inserting some wedges under the struts of the piano to "take out the slack" before I take the measurements.  .  

Norman

Those are all good questions and there are different answers as people take different approaches.  What I posted was just a method of determining the thickness of the new cap in advance of gluing it on.  That's all.  The other questions you ask or much more complicated but worthy of discussion.  They also  require a longer response which I will provide but it will take some time to draft.  In the meantime, I would recommend that everyone read Nick Gravagne's excellent series on downbearing that starts in the 1988 PTJ (February) and runs, I believe, through November of that year.  Many of these questions are addressed, or alluded to.  

Some of the questions are:

1. How many degrees of downbearing should be set in each part of the scale (there are different attitudes about that).  Should we target equal bearing across the scale?  If not, then what?  
2. What, if any difference should there be in along the long bridge versus that bass bridge
3. What about downbearing on older soundboards?
4. How does available crown affect our DB choices?
5. Are the deficiencies you refer to a product of downbearing or are there other factors that might be contributing (hammer characteristics, e.g.)?
6. Does per string downbearing measured after the piano is pulled to pitch actually indicate the load that falls right below that string on the SB?
7. Forces coming from DB are vector forces.  Are those forces always 90 degrees to the SB or are vector forces transmitted in other directions, say along the ribs
8. What kind of residual bearing should we target or expect and what does that mean in terms of our original, pre-tension downbearing settings?
9. The soundboard reacting as a compressed spring is "non-linear", as you mention, so what does that mean in this context and is it important?
10. Should we pre-stress the board before we set bearing, why and how?

I'll come back to those questions but I need a bit more time than I have this morning.  Of course, others can weigh in in the meantime, and, lol, I'm sure they will, for better or for worse.

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320

Original Message:
Sent: 09-16-2025 11:17
From: Norman Brickman
Subject: Downbearing Bridge Cap Thickness Tool

I know very little about bellyman work, but I know that the net outcome of the bridge downbearing is essential to the sound quality: volume, sustain, thinness/weakness, tone, etc with particular sensitivity in the treble. A certain number of the rebuilt grands that I come across, in homes and in stores, have portions of their treble with deficiencies in sound. If I am right in this observation, then what is the probability of success for a typical rebuild?

Your post, David, seems straight-forward for setting the downbearing (in an overall complex process!) before beginning to restring. Is the object to achieve an equal downbearing across the whole scale when you are done restringing, as measured by angle? Or if, as I assume, the (real) target is equality as measured by string downward pressure/force, how many pounds per string do you target for? 

Finally, I have the impression that the physical downbearing (of strings pushing on the bridges) is non-linear across the complete scale. If this is the case, do you somehow have to pre-load against the bridges (when shaping the bridges) to garner your desired downbearing end result after restringing?

Regards, Norman. 

------------------------------
Norman Brickman
Potomac Piano Service
Potomac, Maryland
potomacpiano@verizon.net
https://potomacpiano.com
(301) 983.9321

Original Message:
Sent: 09-16-2025 09:53
From: David Hughes
Subject: Downbearing Bridge Cap Thickness Tool

Terry Farrell (Post #4),

In my opinion (and what do I know, really), a Steinway bridge root/trunk (as one example) is made to the "ideal" height at the factory. This vertically laminated member is strong/unyielding in its original height from end to end, with a cap glued atop that is just tall enough to accommodate the deepest union notches. If we reduce the root to accommodate a thicker cap, we weaken it. The cap material is flexible in its linear dimension; the bridge root is not, and there's a reason for that. The root supports the crown along the grain of the soundboard for the life of the instrument. In my rebuilding work, and again what the heck do I know, I never violated the height of the root. I was much happier "wasting" cap material than reducing the root. I know you use a vertically laminated cap, and perhaps this makes up for the loss (but you have introduced a glue joint that never existed at that elevation, and the root structure would be stronger without it, with continuous vertical grain top-to-bottom, methinks), but I have seen scads of rebuilt Steinway and Mason & Hamlin pianos over the last 45 years with significantly reduced roots and chunky quartersawn maple caps, and they distress me.

David G. Hughes, RPT

Baltimore Chapter

------------------------------
David Hughes RPT
Vintage Case Parts
Glyndon MD
(443) 522-2201

Original Message:
Sent: 09-16-2025 09:19
From: Terrence Farrell
Subject: Downbearing Bridge Cap Thickness Tool

That is very close to the way that I've always set my downbearing. The only difference in my method is that because I use laminated bridge caps and don't really want to be planing down the cap that I just made, what I do is use your method to plane down the bridge root so that after the uniform-thickness cap is added, I get the bridge height I want. When measuring the downbearing for root planing, I simply include a spacer the same thickness of the cap. This has always worked well for me.

Terry Farrell


Original Message:
Sent: 9/15/2025 2:31:00 PM
From: David Love
Subject: Downbearing Bridge Cap Thickness Tool

In a recent discussion with a colleague I was conveying my method of determining bridge cap thickness in advance of gluing on the new cap material.  This way I can plane the new cap to the proper thickness before gluing it on.  I find that easier, and more accurate, than the traditional method of gluing on an oversize (thickness) cap and then cutting slots in the top and then planing the bridge to the depth of those slots. 

The pictures below are pretty self-explanatory.  I've sent a suggestion to Mazzaglia that they produce something like this out of brass, like their other fine tools.  But you can make one of these out of wood easily enough.  I actually found a metal wedge on line which was exactly these dimension that I use for this purpose, adding the markings myself.  The width of the wedge corresponds to the average spacing between the bridge pins.   

Here's a link to the item I purchased recently after my original wooden wedge that I had made got damaged.  Bueyfolt 1/2" x 3/4" x 4" Flange Wedge, Zinc Plated Metal Flange Wedge Pipe Fitting Welding Tool, Strong Welding Wedge, Rust-Proof, Corrosion Resistant and Strong, Spreading Flanges Triangle Tool - Amazon.com 

Procedurally, you determine the distance bearing at the rear string rest by multiplying the length of the backscale by .0175 for each 1 degree of distance bearing that you want (.0175 is the sine of 1 degree).  I then use the Mazzaglia bearing gauges set on top of the rear string rest and lower the string until it rests on the gauge/string rest and then slide the wedge under the string until it just touches the string.  Read the thickness and that's the bridge cap thickness.  By adding the cap thickness to the bridge root height it will give you how high the top of the cap should be above the SB.  I then write in pencil directly on the SB at that point the target height of the bridge with the cap.  I then plane the cap material to that target plus 1 mm and sand the cap to the final height.  Lay out the bridge pin array and go from there. 

I always pre-stress the board by inserting some wedges under the struts of the piano to "take out the slack" before I take the measurements.  .  

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
------------------------------

So getting back to some of the questions in response to Norman's post.  But before I get into it, I have to respond to Chris's comments.  I think an honest discussion of downbearing procedures can bear fruit for everyone.  Chris's comments and criticisms are classic straw man fallacies (it gets tiring correcting the record, honestly).  For those who don't know what that is, it's a logical fallacy that involves misstating or misrepresenting someone's argument, or point, in order to make your argument.  It's a common error, when not a tactic. It doesn't contribute to advancing the discussion. I won't waste a lot of time with it but feel compelled to correct the record. 

First, suggesting that this leads to a 5 degree bearing angle is preposterous.  I've never had that happen and I've never even seen a 5 degree bearing angle on a Steinway of any age in spite of your stated flaws of Steinway processes (careful that might be libelous).  I did not discuss the entire procedure or doing this in a dry fit situation, which I don't do.  I cap and notch the bridge in the piano after the board is glued in with an uncapped bridge root.  I agree, not controlling moisture can be a problem. I doubt it ever leads to a 4 or 5 degree difference but it's certainly possible that it leads to some error.  I think it's best to set the bearing at the anticipated or desired final EMC/RH which is usually about 40 - 50% RH.  

Second, I never said that a 1 degree bearing angle was the target.  In fact, my distance bearing target when determining bridge cap thickness is 1.5 degrees on a prestressed board.  When tension is pulled to pitch I hope the residual bearing is around 1/2 of that, or .75 +/- degrees.  I also set the bearing on bass bridge after the tension is pulled up in the plain wire section and target between 0-.5 degrees (just like Chris whoopee!), but probably closer to .5.  Seems Chris missed an opportunity to agree on something.  

Third, Gravagne doesn't use the quarter-nickel-dime method (I'm pretty sure as we've discussed it).  In fact, in one of those articles he discusses the problems with that method and why it is not reliable!  For those interested, the quarter-nickel-dime method means you are using a quarter for your distance gauge in the low tenor, a nickel in the mid tenor and a dime in the treble.  The reason it's not reliable is that the distance bearing will depend on the length of the backscale.  If you want 1 degree of bearing then the math is to use the sine of the angle of 1 degree (.0175) times the length of the backscale.  That will give you the distance bearing over the rear string rest (see my original illustration).  A quarter is .060" thick.  Thus, multiply .0175* times the length of the backscale and that should equal .060".   So for .060" distance bearing the backscale would have to be ~3.42".  But what if the backscale is 8", as it is on many pianos (Steinway B for example)?  Then the distance bearing would have to be .0175 x 8 or .140"!  That's more than 2.3 times the thickness of a quarter.  (Just a note: my distance bearing setting on a new board is more like 1.5 degrees, the sine of which is ~.026.  So for an 8" backscale, if you wanted 1.5 degrees, you would need a distance bearing of .208", just under a 1/4" and 3.5 times the thickness of a quarter!). I think for Chris, maybe he might get more out of the articles if he read them more carefully and actually understood the details of their content.  I personally just reread them in advance of a DB presentation I was giving to the local chapter, a trial for a class I'm hoping to give later, and I got a lot out of them, including some new questions that didn't occur to me when I read them some 37 years ago.      

The original post was about a tool and its use, nothing more.  I didn't plan to outline my complete method of setting downbearing, bridge cap height or anything else other than show a picture of a tool I use for purposes of measuring and calculating (and it works).  I thought the information might be useful, I found the tool made things easier and more reliable for me.  I'm not selling anything.  I assumed those for whom I posted this were familiar with the process.  But for those who aren't, this is a good opportunity and I'm more than happy to contribute what I know.  If I don't know, I'll say so.  In the words of Oscar Wilde, "I'm not young enough to think I know everything".  

I'll get into answering Norman's questions in a separate post but not tonight.  They are good questions.

Norman

Those are all good questions and there are different answers as people take different approaches.  What I posted was just a method of determining the thickness of the new cap in advance of gluing it on.  That's all.  The other questions you ask or much more complicated but worthy of discussion.  They also  require a longer response which I will provide but it will take some time to draft.  In the meantime, I would recommend that everyone read Nick Gravagne's excellent series on downbearing that starts in the 1988 PTJ (February) and runs, I believe, through November of that year.  Many of these questions are addressed, or alluded to.  

Some of the questions are:

1. How many degrees of downbearing should be set in each part of the scale (there are different attitudes about that).  Should we target equal bearing across the scale?  If not, then what?  
2. What, if any difference should there be in along the long bridge versus that bass bridge
3. What about downbearing on older soundboards?
4. How does available crown affect our DB choices?
5. Are the deficiencies you refer to a product of downbearing or are there other factors that might be contributing (hammer characteristics, e.g.)?
6. Does per string downbearing measured after the piano is pulled to pitch actually indicate the load that falls right below that string on the SB?
7. Forces coming from DB are vector forces.  Are those forces always 90 degrees to the SB or are vector forces transmitted in other directions, say along the ribs
8. What kind of residual bearing should we target or expect and what does that mean in terms of our original, pre-tension downbearing settings?
9. The soundboard reacting as a compressed spring is "non-linear", as you mention, so what does that mean in this context and is it important?
10. Should we pre-stress the board before we set bearing, why and how?

I'll come back to those questions but I need a bit more time than I have this morning.  Of course, others can weigh in in the meantime, and, lol, I'm sure they will, for better or for worse.

I know very little about bellyman work, but I know that the net outcome of the bridge downbearing is essential to the sound quality: volume, sustain, thinness/weakness, tone, etc with particular sensitivity in the treble. A certain number of the rebuilt grands that I come across, in homes and in stores, have portions of their treble with deficiencies in sound. If I am right in this observation, then what is the probability of success for a typical rebuild?

Your post, David, seems straight-forward for setting the downbearing (in an overall complex process!) before beginning to restring. Is the object to achieve an equal downbearing across the whole scale when you are done restringing, as measured by angle? Or if, as I assume, the (real) target is equality as measured by string downward pressure/force, how many pounds per string do you target for? 

Finally, I have the impression that the physical downbearing (of strings pushing on the bridges) is non-linear across the complete scale. If this is the case, do you somehow have to pre-load against the bridges (when shaping the bridges) to garner your desired downbearing end result after restringing?

Regards, Norman. 

Terry Farrell (Post #4),

In my opinion (and what do I know, really), a Steinway bridge root/trunk (as one example) is made to the "ideal" height at the factory. This vertically laminated member is strong/unyielding in its original height from end to end, with a cap glued atop that is just tall enough to accommodate the deepest union notches. If we reduce the root to accommodate a thicker cap, we weaken it. The cap material is flexible in its linear dimension; the bridge root is not, and there's a reason for that. The root supports the crown along the grain of the soundboard for the life of the instrument. In my rebuilding work, and again what the heck do I know, I never violated the height of the root. I was much happier "wasting" cap material than reducing the root. I know you use a vertically laminated cap, and perhaps this makes up for the loss (but you have introduced a glue joint that never existed at that elevation, and the root structure would be stronger without it, with continuous vertical grain top-to-bottom, methinks), but I have seen scads of rebuilt Steinway and Mason & Hamlin pianos over the last 45 years with significantly reduced roots and chunky quartersawn maple caps, and they distress me.

David G. Hughes, RPT

Baltimore Chapter

In a recent discussion with a colleague I was conveying my method of determining bridge cap thickness in advance of gluing on the new cap material.  This way I can plane the new cap to the proper thickness before gluing it on.  I find that easier, and more accurate, than the traditional method of gluing on an oversize (thickness) cap and then cutting slots in the top and then planing the bridge to the depth of those slots. 

The pictures below are pretty self-explanatory.  I've sent a suggestion to Mazzaglia that they produce something like this out of brass, like their other fine tools.  But you can make one of these out of wood easily enough.  I actually found a metal wedge on line which was exactly these dimension that I use for this purpose, adding the markings myself.  The width of the wedge corresponds to the average spacing between the bridge pins.   

Here's a link to the item I purchased recently after my original wooden wedge that I had made got damaged.  Bueyfolt 1/2" x 3/4" x 4" Flange Wedge, Zinc Plated Metal Flange Wedge Pipe Fitting Welding Tool, Strong Welding Wedge, Rust-Proof, Corrosion Resistant and Strong, Spreading Flanges Triangle Tool - Amazon.com 

Procedurally, you determine the distance bearing at the rear string rest by multiplying the length of the backscale by .0175 for each 1 degree of distance bearing that you want (.0175 is the sine of 1 degree).  I then use the Mazzaglia bearing gauges set on top of the rear string rest and lower the string until it rests on the gauge/string rest and then slide the wedge under the string until it just touches the string.  Read the thickness and that's the bridge cap thickness.  By adding the cap thickness to the bridge root height it will give you how high the top of the cap should be above the SB.  I then write in pencil directly on the SB at that point the target height of the bridge with the cap.  I then plane the cap material to that target plus 1 mm and sand the cap to the final height.  Lay out the bridge pin array and go from there. 

I always pre-stress the board by inserting some wedges under the struts of the piano to "take out the slack" before I take the measurements.  .  

Terry Farrell (Post #4),

In my opinion (and what do I know, really), a Steinway bridge root/trunk (as one example) is made to the "ideal" height at the factory. This vertically laminated member is strong/unyielding in its original height from end to end, with a cap glued atop that is just tall enough to accommodate the deepest union notches. If we reduce the root to accommodate a thicker cap, we weaken it. The cap material is flexible in its linear dimension; the bridge root is not, and there's a reason for that. The root supports the crown along the grain of the soundboard for the life of the instrument. In my rebuilding work, and again what the heck do I know, I never violated the height of the root. I was much happier "wasting" cap material than reducing the root. I know you use a vertically laminated cap, and perhaps this makes up for the loss (but you have introduced a glue joint that never existed at that elevation, and the root structure would be stronger without it, with continuous vertical grain top-to-bottom, methinks), but I have seen scads of rebuilt Steinway and Mason & Hamlin pianos over the last 45 years with significantly reduced roots and chunky quartersawn maple caps, and they distress me.

David G. Hughes, RPT

Baltimore Chapter

In a recent discussion with a colleague I was conveying my method of determining bridge cap thickness in advance of gluing on the new cap material.  This way I can plane the new cap to the proper thickness before gluing it on.  I find that easier, and more accurate, than the traditional method of gluing on an oversize (thickness) cap and then cutting slots in the top and then planing the bridge to the depth of those slots. 

The pictures below are pretty self-explanatory.  I've sent a suggestion to Mazzaglia that they produce something like this out of brass, like their other fine tools.  But you can make one of these out of wood easily enough.  I actually found a metal wedge on line which was exactly these dimension that I use for this purpose, adding the markings myself.  The width of the wedge corresponds to the average spacing between the bridge pins.   

Here's a link to the item I purchased recently after my original wooden wedge that I had made got damaged.  Bueyfolt 1/2" x 3/4" x 4" Flange Wedge, Zinc Plated Metal Flange Wedge Pipe Fitting Welding Tool, Strong Welding Wedge, Rust-Proof, Corrosion Resistant and Strong, Spreading Flanges Triangle Tool - Amazon.com 

Procedurally, you determine the distance bearing at the rear string rest by multiplying the length of the backscale by .0175 for each 1 degree of distance bearing that you want (.0175 is the sine of 1 degree).  I then use the Mazzaglia bearing gauges set on top of the rear string rest and lower the string until it rests on the gauge/string rest and then slide the wedge under the string until it just touches the string.  Read the thickness and that's the bridge cap thickness.  By adding the cap thickness to the bridge root height it will give you how high the top of the cap should be above the SB.  I then write in pencil directly on the SB at that point the target height of the bridge with the cap.  I then plane the cap material to that target plus 1 mm and sand the cap to the final height.  Lay out the bridge pin array and go from there. 

I always pre-stress the board by inserting some wedges under the struts of the piano to "take out the slack" before I take the measurements.  .  

David H

I agree with that, but who said anything about reducing the height of the bridge root?  When I'm recapping a bridge I remove the cap which I do in one piece (each section), which is easy to do an old Steinway Bridge, leaving the root intact.  The method I have outlined is determining the thickness of the new cap, no more, no less.  

Terry Farrell (Post #4),

In my opinion (and what do I know, really), a Steinway bridge root/trunk (as one example) is made to the "ideal" height at the factory. This vertically laminated member is strong/unyielding in its original height from end to end, with a cap glued atop that is just tall enough to accommodate the deepest union notches. If we reduce the root to accommodate a thicker cap, we weaken it. The cap material is flexible in its linear dimension; the bridge root is not, and there's a reason for that. The root supports the crown along the grain of the soundboard for the life of the instrument. In my rebuilding work, and again what the heck do I know, I never violated the height of the root. I was much happier "wasting" cap material than reducing the root. I know you use a vertically laminated cap, and perhaps this makes up for the loss (but you have introduced a glue joint that never existed at that elevation, and the root structure would be stronger without it, with continuous vertical grain top-to-bottom, methinks), but I have seen scads of rebuilt Steinway and Mason & Hamlin pianos over the last 45 years with significantly reduced roots and chunky quartersawn maple caps, and they distress me.

David G. Hughes, RPT

Baltimore Chapter

In a recent discussion with a colleague I was conveying my method of determining bridge cap thickness in advance of gluing on the new cap material.  This way I can plane the new cap to the proper thickness before gluing it on.  I find that easier, and more accurate, than the traditional method of gluing on an oversize (thickness) cap and then cutting slots in the top and then planing the bridge to the depth of those slots. 

The pictures below are pretty self-explanatory.  I've sent a suggestion to Mazzaglia that they produce something like this out of brass, like their other fine tools.  But you can make one of these out of wood easily enough.  I actually found a metal wedge on line which was exactly these dimension that I use for this purpose, adding the markings myself.  The width of the wedge corresponds to the average spacing between the bridge pins.   

Here's a link to the item I purchased recently after my original wooden wedge that I had made got damaged.  Bueyfolt 1/2" x 3/4" x 4" Flange Wedge, Zinc Plated Metal Flange Wedge Pipe Fitting Welding Tool, Strong Welding Wedge, Rust-Proof, Corrosion Resistant and Strong, Spreading Flanges Triangle Tool - Amazon.com 

Procedurally, you determine the distance bearing at the rear string rest by multiplying the length of the backscale by .0175 for each 1 degree of distance bearing that you want (.0175 is the sine of 1 degree).  I then use the Mazzaglia bearing gauges set on top of the rear string rest and lower the string until it rests on the gauge/string rest and then slide the wedge under the string until it just touches the string.  Read the thickness and that's the bridge cap thickness.  By adding the cap thickness to the bridge root height it will give you how high the top of the cap should be above the SB.  I then write in pencil directly on the SB at that point the target height of the bridge with the cap.  I then plane the cap material to that target plus 1 mm and sand the cap to the final height.  Lay out the bridge pin array and go from there. 

I always pre-stress the board by inserting some wedges under the struts of the piano to "take out the slack" before I take the measurements.  .  

David Love (Post #10),

I was commenting on Terry Farrell's procedure of reducing the bridge root/trunk to apply a thick cap. I was not implying that was your procedure.

David G. Hughes, RPT

Baltimore Chapter

David H

I agree with that, but who said anything about reducing the height of the bridge root?  When I'm recapping a bridge I remove the cap which I do in one piece (each section), which is easy to do an old Steinway Bridge, leaving the root intact.  The method I have outlined is determining the thickness of the new cap, no more, no less.  

Terry Farrell (Post #4),

In my opinion (and what do I know, really), a Steinway bridge root/trunk (as one example) is made to the "ideal" height at the factory. This vertically laminated member is strong/unyielding in its original height from end to end, with a cap glued atop that is just tall enough to accommodate the deepest union notches. If we reduce the root to accommodate a thicker cap, we weaken it. The cap material is flexible in its linear dimension; the bridge root is not, and there's a reason for that. The root supports the crown along the grain of the soundboard for the life of the instrument. In my rebuilding work, and again what the heck do I know, I never violated the height of the root. I was much happier "wasting" cap material than reducing the root. I know you use a vertically laminated cap, and perhaps this makes up for the loss (but you have introduced a glue joint that never existed at that elevation, and the root structure would be stronger without it, with continuous vertical grain top-to-bottom, methinks), but I have seen scads of rebuilt Steinway and Mason & Hamlin pianos over the last 45 years with significantly reduced roots and chunky quartersawn maple caps, and they distress me.

David G. Hughes, RPT

Baltimore Chapter

In a recent discussion with a colleague I was conveying my method of determining bridge cap thickness in advance of gluing on the new cap material.  This way I can plane the new cap to the proper thickness before gluing it on.  I find that easier, and more accurate, than the traditional method of gluing on an oversize (thickness) cap and then cutting slots in the top and then planing the bridge to the depth of those slots. 

The pictures below are pretty self-explanatory.  I've sent a suggestion to Mazzaglia that they produce something like this out of brass, like their other fine tools.  But you can make one of these out of wood easily enough.  I actually found a metal wedge on line which was exactly these dimension that I use for this purpose, adding the markings myself.  The width of the wedge corresponds to the average spacing between the bridge pins.   

Here's a link to the item I purchased recently after my original wooden wedge that I had made got damaged.  Bueyfolt 1/2" x 3/4" x 4" Flange Wedge, Zinc Plated Metal Flange Wedge Pipe Fitting Welding Tool, Strong Welding Wedge, Rust-Proof, Corrosion Resistant and Strong, Spreading Flanges Triangle Tool - Amazon.com 

Procedurally, you determine the distance bearing at the rear string rest by multiplying the length of the backscale by .0175 for each 1 degree of distance bearing that you want (.0175 is the sine of 1 degree).  I then use the Mazzaglia bearing gauges set on top of the rear string rest and lower the string until it rests on the gauge/string rest and then slide the wedge under the string until it just touches the string.  Read the thickness and that's the bridge cap thickness.  By adding the cap thickness to the bridge root height it will give you how high the top of the cap should be above the SB.  I then write in pencil directly on the SB at that point the target height of the bridge with the cap.  I then plane the cap material to that target plus 1 mm and sand the cap to the final height.  Lay out the bridge pin array and go from there. 

I always pre-stress the board by inserting some wedges under the struts of the piano to "take out the slack" before I take the measurements.  .  

David H. 

Missed that, I stand corrected. 

David Love (Post #10),

I was commenting on Terry Farrell's procedure of reducing the bridge root/trunk to apply a thick cap. I was not implying that was your procedure.

David G. Hughes, RPT

Baltimore Chapter

David H

I agree with that, but who said anything about reducing the height of the bridge root?  When I'm recapping a bridge I remove the cap which I do in one piece (each section), which is easy to do an old Steinway Bridge, leaving the root intact.  The method I have outlined is determining the thickness of the new cap, no more, no less.  

Terry Farrell (Post #4),

In my opinion (and what do I know, really), a Steinway bridge root/trunk (as one example) is made to the "ideal" height at the factory. This vertically laminated member is strong/unyielding in its original height from end to end, with a cap glued atop that is just tall enough to accommodate the deepest union notches. If we reduce the root to accommodate a thicker cap, we weaken it. The cap material is flexible in its linear dimension; the bridge root is not, and there's a reason for that. The root supports the crown along the grain of the soundboard for the life of the instrument. In my rebuilding work, and again what the heck do I know, I never violated the height of the root. I was much happier "wasting" cap material than reducing the root. I know you use a vertically laminated cap, and perhaps this makes up for the loss (but you have introduced a glue joint that never existed at that elevation, and the root structure would be stronger without it, with continuous vertical grain top-to-bottom, methinks), but I have seen scads of rebuilt Steinway and Mason & Hamlin pianos over the last 45 years with significantly reduced roots and chunky quartersawn maple caps, and they distress me.

David G. Hughes, RPT

Baltimore Chapter

In a recent discussion with a colleague I was conveying my method of determining bridge cap thickness in advance of gluing on the new cap material.  This way I can plane the new cap to the proper thickness before gluing it on.  I find that easier, and more accurate, than the traditional method of gluing on an oversize (thickness) cap and then cutting slots in the top and then planing the bridge to the depth of those slots. 

The pictures below are pretty self-explanatory.  I've sent a suggestion to Mazzaglia that they produce something like this out of brass, like their other fine tools.  But you can make one of these out of wood easily enough.  I actually found a metal wedge on line which was exactly these dimension that I use for this purpose, adding the markings myself.  The width of the wedge corresponds to the average spacing between the bridge pins.   

Here's a link to the item I purchased recently after my original wooden wedge that I had made got damaged.  Bueyfolt 1/2" x 3/4" x 4" Flange Wedge, Zinc Plated Metal Flange Wedge Pipe Fitting Welding Tool, Strong Welding Wedge, Rust-Proof, Corrosion Resistant and Strong, Spreading Flanges Triangle Tool - Amazon.com 

Procedurally, you determine the distance bearing at the rear string rest by multiplying the length of the backscale by .0175 for each 1 degree of distance bearing that you want (.0175 is the sine of 1 degree).  I then use the Mazzaglia bearing gauges set on top of the rear string rest and lower the string until it rests on the gauge/string rest and then slide the wedge under the string until it just touches the string.  Read the thickness and that's the bridge cap thickness.  By adding the cap thickness to the bridge root height it will give you how high the top of the cap should be above the SB.  I then write in pencil directly on the SB at that point the target height of the bridge with the cap.  I then plane the cap material to that target plus 1 mm and sand the cap to the final height.  Lay out the bridge pin array and go from there. 

I always pre-stress the board by inserting some wedges under the struts of the piano to "take out the slack" before I take the measurements.  .  

David, thanks for the PTJ reference – I scanned a little but look forward to your summary. There is a lot of complexity in the topic so you can't cover it all here. I only picked up on a few things so far, like uniform downbearing pressure throughout being desired; and the general range of around 4 pounds downbearing per string; and a usual practical leeway of +/- 1 ½ degrees of deflection (which I think I am leary of!); and the trig functions; and the practical use of a rear spacer.

At one point Nick started to get into the "non-linear" nature of the effect of stringing on physical downbearing throughout the scale that interests me, referring to a 1/16" deflection from pressure applied in another area of the soundboard. As I say, I am looking forward to your summary! Unfortunately, I presume that the more complexity there is, the more potential for tonal deficiencies after a rebuilding that I referred to. Regards, Norman 

David H. 

Missed that, I stand corrected. 

David Love (Post #10),

I was commenting on Terry Farrell's procedure of reducing the bridge root/trunk to apply a thick cap. I was not implying that was your procedure.

David G. Hughes, RPT

Baltimore Chapter

David H

I agree with that, but who said anything about reducing the height of the bridge root?  When I'm recapping a bridge I remove the cap which I do in one piece (each section), which is easy to do an old Steinway Bridge, leaving the root intact.  The method I have outlined is determining the thickness of the new cap, no more, no less.  

Terry Farrell (Post #4),

In my opinion (and what do I know, really), a Steinway bridge root/trunk (as one example) is made to the "ideal" height at the factory. This vertically laminated member is strong/unyielding in its original height from end to end, with a cap glued atop that is just tall enough to accommodate the deepest union notches. If we reduce the root to accommodate a thicker cap, we weaken it. The cap material is flexible in its linear dimension; the bridge root is not, and there's a reason for that. The root supports the crown along the grain of the soundboard for the life of the instrument. In my rebuilding work, and again what the heck do I know, I never violated the height of the root. I was much happier "wasting" cap material than reducing the root. I know you use a vertically laminated cap, and perhaps this makes up for the loss (but you have introduced a glue joint that never existed at that elevation, and the root structure would be stronger without it, with continuous vertical grain top-to-bottom, methinks), but I have seen scads of rebuilt Steinway and Mason & Hamlin pianos over the last 45 years with significantly reduced roots and chunky quartersawn maple caps, and they distress me.

David G. Hughes, RPT

Baltimore Chapter

In a recent discussion with a colleague I was conveying my method of determining bridge cap thickness in advance of gluing on the new cap material.  This way I can plane the new cap to the proper thickness before gluing it on.  I find that easier, and more accurate, than the traditional method of gluing on an oversize (thickness) cap and then cutting slots in the top and then planing the bridge to the depth of those slots. 

The pictures below are pretty self-explanatory.  I've sent a suggestion to Mazzaglia that they produce something like this out of brass, like their other fine tools.  But you can make one of these out of wood easily enough.  I actually found a metal wedge on line which was exactly these dimension that I use for this purpose, adding the markings myself.  The width of the wedge corresponds to the average spacing between the bridge pins.   

Here's a link to the item I purchased recently after my original wooden wedge that I had made got damaged.  Bueyfolt 1/2" x 3/4" x 4" Flange Wedge, Zinc Plated Metal Flange Wedge Pipe Fitting Welding Tool, Strong Welding Wedge, Rust-Proof, Corrosion Resistant and Strong, Spreading Flanges Triangle Tool - Amazon.com 

Procedurally, you determine the distance bearing at the rear string rest by multiplying the length of the backscale by .0175 for each 1 degree of distance bearing that you want (.0175 is the sine of 1 degree).  I then use the Mazzaglia bearing gauges set on top of the rear string rest and lower the string until it rests on the gauge/string rest and then slide the wedge under the string until it just touches the string.  Read the thickness and that's the bridge cap thickness.  By adding the cap thickness to the bridge root height it will give you how high the top of the cap should be above the SB.  I then write in pencil directly on the SB at that point the target height of the bridge with the cap.  I then plane the cap material to that target plus 1 mm and sand the cap to the final height.  Lay out the bridge pin array and go from there. 

I always pre-stress the board by inserting some wedges under the struts of the piano to "take out the slack" before I take the measurements.  .  

Just a word of caution to all.: This new method ( which i abandoned 10 years ago) will give you a severe downbearing angle (all while thinking your setting a 1 degree angle) most of the time. Have you guys ever seen a Steinway with a 5 degree downbearing angle? I have numerous times. Its because of dry fitting, not controlling moisture in the shop, and pre loading. With those methods you end up with a mystery uneven downbearing across the board. Even if you choose to use WNG perimeter bolts your limited by the bass bridge how much you can go up.  With High DB you shorten the life of the board ( i already mentioned how it hurts the tone). And when your boards are flattening out, and the tone deadening, one starts thinking to change the rib scale.  The fact that Steinway does downbearing wrong in tandem with a scaled missing rib (compared to other brands) and diaphragmatic crappola means a true light DB is essential. Instead of all that sine of the angle stuff (with its accompanying thickness gauges,  i use custom made little tiny string levels.. Setting downbearing directly in the piano eliminates errors that can occur with adding extra steps from  dry fitting mishaps. I also notch in the piano because even with indexing i want good sidebearing as well. Which is another issue with benching it. What wasn't mentioned which is extremely important is don't do downbearing until the board and room is at the right Moisture %. This should be mentioned because of the newbies out there..

There's not a single thing from the Gravagne articles i found useful and use. The installation order is wrong, use a nickel here a quarter there ( oh the accuracy), and i don't know who the frick Bonnano is. I do recommend the Lowell articles though. And i do refine my downbearing as i string as well because the whole process is working with a moving spring. I'm pretty confident that in the end i get exactly the 1 degree i want on the long bridge and i go for a 0 - .5 degree on the bass bridge

-chris

David, thanks for the PTJ reference – I scanned a little but look forward to your summary. There is a lot of complexity in the topic so you can't cover it all here. I only picked up on a few things so far, like uniform downbearing pressure throughout being desired; and the general range of around 4 pounds downbearing per string; and a usual practical leeway of +/- 1 ½ degrees of deflection (which I think I am leary of!); and the trig functions; and the practical use of a rear spacer.

At one point Nick started to get into the "non-linear" nature of the effect of stringing on physical downbearing throughout the scale that interests me, referring to a 1/16" deflection from pressure applied in another area of the soundboard. As I say, I am looking forward to your summary! Unfortunately, I presume that the more complexity there is, the more potential for tonal deficiencies after a rebuilding that I referred to. Regards, Norman 

David H. 

Missed that, I stand corrected. 

David Love (Post #10),

I was commenting on Terry Farrell's procedure of reducing the bridge root/trunk to apply a thick cap. I was not implying that was your procedure.

David G. Hughes, RPT

Baltimore Chapter

David H

I agree with that, but who said anything about reducing the height of the bridge root?  When I'm recapping a bridge I remove the cap which I do in one piece (each section), which is easy to do an old Steinway Bridge, leaving the root intact.  The method I have outlined is determining the thickness of the new cap, no more, no less.  

Terry Farrell (Post #4),

In my opinion (and what do I know, really), a Steinway bridge root/trunk (as one example) is made to the "ideal" height at the factory. This vertically laminated member is strong/unyielding in its original height from end to end, with a cap glued atop that is just tall enough to accommodate the deepest union notches. If we reduce the root to accommodate a thicker cap, we weaken it. The cap material is flexible in its linear dimension; the bridge root is not, and there's a reason for that. The root supports the crown along the grain of the soundboard for the life of the instrument. In my rebuilding work, and again what the heck do I know, I never violated the height of the root. I was much happier "wasting" cap material than reducing the root. I know you use a vertically laminated cap, and perhaps this makes up for the loss (but you have introduced a glue joint that never existed at that elevation, and the root structure would be stronger without it, with continuous vertical grain top-to-bottom, methinks), but I have seen scads of rebuilt Steinway and Mason & Hamlin pianos over the last 45 years with significantly reduced roots and chunky quartersawn maple caps, and they distress me.

David G. Hughes, RPT

Baltimore Chapter

In a recent discussion with a colleague I was conveying my method of determining bridge cap thickness in advance of gluing on the new cap material.  This way I can plane the new cap to the proper thickness before gluing it on.  I find that easier, and more accurate, than the traditional method of gluing on an oversize (thickness) cap and then cutting slots in the top and then planing the bridge to the depth of those slots. 

The pictures below are pretty self-explanatory.  I've sent a suggestion to Mazzaglia that they produce something like this out of brass, like their other fine tools.  But you can make one of these out of wood easily enough.  I actually found a metal wedge on line which was exactly these dimension that I use for this purpose, adding the markings myself.  The width of the wedge corresponds to the average spacing between the bridge pins.   

Here's a link to the item I purchased recently after my original wooden wedge that I had made got damaged.  Bueyfolt 1/2" x 3/4" x 4" Flange Wedge, Zinc Plated Metal Flange Wedge Pipe Fitting Welding Tool, Strong Welding Wedge, Rust-Proof, Corrosion Resistant and Strong, Spreading Flanges Triangle Tool - Amazon.com 

Procedurally, you determine the distance bearing at the rear string rest by multiplying the length of the backscale by .0175 for each 1 degree of distance bearing that you want (.0175 is the sine of 1 degree).  I then use the Mazzaglia bearing gauges set on top of the rear string rest and lower the string until it rests on the gauge/string rest and then slide the wedge under the string until it just touches the string.  Read the thickness and that's the bridge cap thickness.  By adding the cap thickness to the bridge root height it will give you how high the top of the cap should be above the SB.  I then write in pencil directly on the SB at that point the target height of the bridge with the cap.  I then plane the cap material to that target plus 1 mm and sand the cap to the final height.  Lay out the bridge pin array and go from there. 

I always pre-stress the board by inserting some wedges under the struts of the piano to "take out the slack" before I take the measurements.  .  

Is it just me, or is the tone of Post #16 a tad offensive?

David G. Hughes, RPT

Baltimore Chapter

Just a word of caution to all.: This new method ( which i abandoned 10 years ago) will give you a severe downbearing angle (all while thinking your setting a 1 degree angle) most of the time. Have you guys ever seen a Steinway with a 5 degree downbearing angle? I have numerous times. Its because of dry fitting, not controlling moisture in the shop, and pre loading. With those methods you end up with a mystery uneven downbearing across the board. Even if you choose to use WNG perimeter bolts your limited by the bass bridge how much you can go up.  With High DB you shorten the life of the board ( i already mentioned how it hurts the tone). And when your boards are flattening out, and the tone deadening, one starts thinking to change the rib scale.  The fact that Steinway does downbearing wrong in tandem with a scaled missing rib (compared to other brands) and diaphragmatic crappola means a true light DB is essential. Instead of all that sine of the angle stuff (with its accompanying thickness gauges,  i use custom made little tiny string levels.. Setting downbearing directly in the piano eliminates errors that can occur with adding extra steps from  dry fitting mishaps. I also notch in the piano because even with indexing i want good sidebearing as well. Which is another issue with benching it. What wasn't mentioned which is extremely important is don't do downbearing until the board and room is at the right Moisture %. This should be mentioned because of the newbies out there..

There's not a single thing from the Gravagne articles i found useful and use. The installation order is wrong, use a nickel here a quarter there ( oh the accuracy), and i don't know who the frick Bonnano is. I do recommend the Lowell articles though. And i do refine my downbearing as i string as well because the whole process is working with a moving spring. I'm pretty confident that in the end i get exactly the 1 degree i want on the long bridge and i go for a 0 - .5 degree on the bass bridge

-chris

David, thanks for the PTJ reference – I scanned a little but look forward to your summary. There is a lot of complexity in the topic so you can't cover it all here. I only picked up on a few things so far, like uniform downbearing pressure throughout being desired; and the general range of around 4 pounds downbearing per string; and a usual practical leeway of +/- 1 ½ degrees of deflection (which I think I am leary of!); and the trig functions; and the practical use of a rear spacer.

At one point Nick started to get into the "non-linear" nature of the effect of stringing on physical downbearing throughout the scale that interests me, referring to a 1/16" deflection from pressure applied in another area of the soundboard. As I say, I am looking forward to your summary! Unfortunately, I presume that the more complexity there is, the more potential for tonal deficiencies after a rebuilding that I referred to. Regards, Norman 

David H. 

Missed that, I stand corrected. 

David Love (Post #10),

I was commenting on Terry Farrell's procedure of reducing the bridge root/trunk to apply a thick cap. I was not implying that was your procedure.

David G. Hughes, RPT

Baltimore Chapter

David H

I agree with that, but who said anything about reducing the height of the bridge root?  When I'm recapping a bridge I remove the cap which I do in one piece (each section), which is easy to do an old Steinway Bridge, leaving the root intact.  The method I have outlined is determining the thickness of the new cap, no more, no less.  

Terry Farrell (Post #4),

In my opinion (and what do I know, really), a Steinway bridge root/trunk (as one example) is made to the "ideal" height at the factory. This vertically laminated member is strong/unyielding in its original height from end to end, with a cap glued atop that is just tall enough to accommodate the deepest union notches. If we reduce the root to accommodate a thicker cap, we weaken it. The cap material is flexible in its linear dimension; the bridge root is not, and there's a reason for that. The root supports the crown along the grain of the soundboard for the life of the instrument. In my rebuilding work, and again what the heck do I know, I never violated the height of the root. I was much happier "wasting" cap material than reducing the root. I know you use a vertically laminated cap, and perhaps this makes up for the loss (but you have introduced a glue joint that never existed at that elevation, and the root structure would be stronger without it, with continuous vertical grain top-to-bottom, methinks), but I have seen scads of rebuilt Steinway and Mason & Hamlin pianos over the last 45 years with significantly reduced roots and chunky quartersawn maple caps, and they distress me.

David G. Hughes, RPT

Baltimore Chapter

In a recent discussion with a colleague I was conveying my method of determining bridge cap thickness in advance of gluing on the new cap material.  This way I can plane the new cap to the proper thickness before gluing it on.  I find that easier, and more accurate, than the traditional method of gluing on an oversize (thickness) cap and then cutting slots in the top and then planing the bridge to the depth of those slots. 

The pictures below are pretty self-explanatory.  I've sent a suggestion to Mazzaglia that they produce something like this out of brass, like their other fine tools.  But you can make one of these out of wood easily enough.  I actually found a metal wedge on line which was exactly these dimension that I use for this purpose, adding the markings myself.  The width of the wedge corresponds to the average spacing between the bridge pins.   

Here's a link to the item I purchased recently after my original wooden wedge that I had made got damaged.  Bueyfolt 1/2" x 3/4" x 4" Flange Wedge, Zinc Plated Metal Flange Wedge Pipe Fitting Welding Tool, Strong Welding Wedge, Rust-Proof, Corrosion Resistant and Strong, Spreading Flanges Triangle Tool - Amazon.com 

Procedurally, you determine the distance bearing at the rear string rest by multiplying the length of the backscale by .0175 for each 1 degree of distance bearing that you want (.0175 is the sine of 1 degree).  I then use the Mazzaglia bearing gauges set on top of the rear string rest and lower the string until it rests on the gauge/string rest and then slide the wedge under the string until it just touches the string.  Read the thickness and that's the bridge cap thickness.  By adding the cap thickness to the bridge root height it will give you how high the top of the cap should be above the SB.  I then write in pencil directly on the SB at that point the target height of the bridge with the cap.  I then plane the cap material to that target plus 1 mm and sand the cap to the final height.  Lay out the bridge pin array and go from there. 

I always pre-stress the board by inserting some wedges under the struts of the piano to "take out the slack" before I take the measurements.  .  

Dear Chris,

I think it's a little unfair to say something is done wrong because it is sometimes done under not ideal conditions and there can be errors. If you don't like a method because you think it's more prone to errors for reasons x, y and z, that's great. I'd love to hear it. But you present your way as the only right way, and belittle the way that others do it. Perhaps your way is the best way. Let's have a conversation about different methods. I know for me, what works well for me doesn't work well for someone else, and yet we both get a wonderful outcome. 

I did consider writing you privately, but I've noticed you employ a more aggressive diatribe against Mr. Love routinely in public. As I've said before, I've learned very much from both of you, and have a great deal of respect for both of your attention to detail and your ability to think outside the box in search of excellence. I still believe this about both of you.

However, your belittling tone and bellicose rhetoric really needs to stop. I don't know what you think you're accomplishing by it, but to me it seems that you are possibly angry at something else and Mr Love is your scapegoat. It comes across as an insecurity at best, and narcissism at worst. Please know, I am not saying this is what it is, it is just how it comes across to me.

I believe that as a society, we need to learn how to make an argument without attacking the person. I'm very attracted to a forum like this because there are many very bright people willing to share information and even disagree with the methods of others. We can learn so much! Please, please, try to communicate in a respectful way that is conducive to the excellence for which we all strive.

Is it just me, or is the tone of Post #16 a tad offensive?

David G. Hughes, RPT

Baltimore Chapter

Just a word of caution to all.: This new method ( which i abandoned 10 years ago) will give you a severe downbearing angle (all while thinking your setting a 1 degree angle) most of the time. Have you guys ever seen a Steinway with a 5 degree downbearing angle? I have numerous times. Its because of dry fitting, not controlling moisture in the shop, and pre loading. With those methods you end up with a mystery uneven downbearing across the board. Even if you choose to use WNG perimeter bolts your limited by the bass bridge how much you can go up.  With High DB you shorten the life of the board ( i already mentioned how it hurts the tone). And when your boards are flattening out, and the tone deadening, one starts thinking to change the rib scale.  The fact that Steinway does downbearing wrong in tandem with a scaled missing rib (compared to other brands) and diaphragmatic crappola means a true light DB is essential. Instead of all that sine of the angle stuff (with its accompanying thickness gauges,  i use custom made little tiny string levels.. Setting downbearing directly in the piano eliminates errors that can occur with adding extra steps from  dry fitting mishaps. I also notch in the piano because even with indexing i want good sidebearing as well. Which is another issue with benching it. What wasn't mentioned which is extremely important is don't do downbearing until the board and room is at the right Moisture %. This should be mentioned because of the newbies out there..

There's not a single thing from the Gravagne articles i found useful and use. The installation order is wrong, use a nickel here a quarter there ( oh the accuracy), and i don't know who the frick Bonnano is. I do recommend the Lowell articles though. And i do refine my downbearing as i string as well because the whole process is working with a moving spring. I'm pretty confident that in the end i get exactly the 1 degree i want on the long bridge and i go for a 0 - .5 degree on the bass bridge

-chris

David, thanks for the PTJ reference – I scanned a little but look forward to your summary. There is a lot of complexity in the topic so you can't cover it all here. I only picked up on a few things so far, like uniform downbearing pressure throughout being desired; and the general range of around 4 pounds downbearing per string; and a usual practical leeway of +/- 1 ½ degrees of deflection (which I think I am leary of!); and the trig functions; and the practical use of a rear spacer.

At one point Nick started to get into the "non-linear" nature of the effect of stringing on physical downbearing throughout the scale that interests me, referring to a 1/16" deflection from pressure applied in another area of the soundboard. As I say, I am looking forward to your summary! Unfortunately, I presume that the more complexity there is, the more potential for tonal deficiencies after a rebuilding that I referred to. Regards, Norman 

David H. 

Missed that, I stand corrected. 

David Love (Post #10),

I was commenting on Terry Farrell's procedure of reducing the bridge root/trunk to apply a thick cap. I was not implying that was your procedure.

David G. Hughes, RPT

Baltimore Chapter

David H

I agree with that, but who said anything about reducing the height of the bridge root?  When I'm recapping a bridge I remove the cap which I do in one piece (each section), which is easy to do an old Steinway Bridge, leaving the root intact.  The method I have outlined is determining the thickness of the new cap, no more, no less.  

Terry Farrell (Post #4),

In my opinion (and what do I know, really), a Steinway bridge root/trunk (as one example) is made to the "ideal" height at the factory. This vertically laminated member is strong/unyielding in its original height from end to end, with a cap glued atop that is just tall enough to accommodate the deepest union notches. If we reduce the root to accommodate a thicker cap, we weaken it. The cap material is flexible in its linear dimension; the bridge root is not, and there's a reason for that. The root supports the crown along the grain of the soundboard for the life of the instrument. In my rebuilding work, and again what the heck do I know, I never violated the height of the root. I was much happier "wasting" cap material than reducing the root. I know you use a vertically laminated cap, and perhaps this makes up for the loss (but you have introduced a glue joint that never existed at that elevation, and the root structure would be stronger without it, with continuous vertical grain top-to-bottom, methinks), but I have seen scads of rebuilt Steinway and Mason & Hamlin pianos over the last 45 years with significantly reduced roots and chunky quartersawn maple caps, and they distress me.

David G. Hughes, RPT

Baltimore Chapter

In a recent discussion with a colleague I was conveying my method of determining bridge cap thickness in advance of gluing on the new cap material.  This way I can plane the new cap to the proper thickness before gluing it on.  I find that easier, and more accurate, than the traditional method of gluing on an oversize (thickness) cap and then cutting slots in the top and then planing the bridge to the depth of those slots. 

The pictures below are pretty self-explanatory.  I've sent a suggestion to Mazzaglia that they produce something like this out of brass, like their other fine tools.  But you can make one of these out of wood easily enough.  I actually found a metal wedge on line which was exactly these dimension that I use for this purpose, adding the markings myself.  The width of the wedge corresponds to the average spacing between the bridge pins.   

Here's a link to the item I purchased recently after my original wooden wedge that I had made got damaged.  Bueyfolt 1/2" x 3/4" x 4" Flange Wedge, Zinc Plated Metal Flange Wedge Pipe Fitting Welding Tool, Strong Welding Wedge, Rust-Proof, Corrosion Resistant and Strong, Spreading Flanges Triangle Tool - Amazon.com 

Procedurally, you determine the distance bearing at the rear string rest by multiplying the length of the backscale by .0175 for each 1 degree of distance bearing that you want (.0175 is the sine of 1 degree).  I then use the Mazzaglia bearing gauges set on top of the rear string rest and lower the string until it rests on the gauge/string rest and then slide the wedge under the string until it just touches the string.  Read the thickness and that's the bridge cap thickness.  By adding the cap thickness to the bridge root height it will give you how high the top of the cap should be above the SB.  I then write in pencil directly on the SB at that point the target height of the bridge with the cap.  I then plane the cap material to that target plus 1 mm and sand the cap to the final height.  Lay out the bridge pin array and go from there. 

I always pre-stress the board by inserting some wedges under the struts of the piano to "take out the slack" before I take the measurements.  .  

David H

I agree with that, but who said anything about reducing the height of the bridge root?  When I'm recapping a bridge I remove the cap which I do in one piece (each section), which is easy to do an old Steinway Bridge, leaving the root intact.  The method I have outlined is determining the thickness of the new cap, no more, no less.  

Terry Farrell (Post #4),

In my opinion (and what do I know, really), a Steinway bridge root/trunk (as one example) is made to the "ideal" height at the factory. This vertically laminated member is strong/unyielding in its original height from end to end, with a cap glued atop that is just tall enough to accommodate the deepest union notches. If we reduce the root to accommodate a thicker cap, we weaken it. The cap material is flexible in its linear dimension; the bridge root is not, and there's a reason for that. The root supports the crown along the grain of the soundboard for the life of the instrument. In my rebuilding work, and again what the heck do I know, I never violated the height of the root. I was much happier "wasting" cap material than reducing the root. I know you use a vertically laminated cap, and perhaps this makes up for the loss (but you have introduced a glue joint that never existed at that elevation, and the root structure would be stronger without it, with continuous vertical grain top-to-bottom, methinks), but I have seen scads of rebuilt Steinway and Mason & Hamlin pianos over the last 45 years with significantly reduced roots and chunky quartersawn maple caps, and they distress me.

David G. Hughes, RPT

Baltimore Chapter

In a recent discussion with a colleague I was conveying my method of determining bridge cap thickness in advance of gluing on the new cap material.  This way I can plane the new cap to the proper thickness before gluing it on.  I find that easier, and more accurate, than the traditional method of gluing on an oversize (thickness) cap and then cutting slots in the top and then planing the bridge to the depth of those slots. 

The pictures below are pretty self-explanatory.  I've sent a suggestion to Mazzaglia that they produce something like this out of brass, like their other fine tools.  But you can make one of these out of wood easily enough.  I actually found a metal wedge on line which was exactly these dimension that I use for this purpose, adding the markings myself.  The width of the wedge corresponds to the average spacing between the bridge pins.   

Here's a link to the item I purchased recently after my original wooden wedge that I had made got damaged.  Bueyfolt 1/2" x 3/4" x 4" Flange Wedge, Zinc Plated Metal Flange Wedge Pipe Fitting Welding Tool, Strong Welding Wedge, Rust-Proof, Corrosion Resistant and Strong, Spreading Flanges Triangle Tool - Amazon.com 

Procedurally, you determine the distance bearing at the rear string rest by multiplying the length of the backscale by .0175 for each 1 degree of distance bearing that you want (.0175 is the sine of 1 degree).  I then use the Mazzaglia bearing gauges set on top of the rear string rest and lower the string until it rests on the gauge/string rest and then slide the wedge under the string until it just touches the string.  Read the thickness and that's the bridge cap thickness.  By adding the cap thickness to the bridge root height it will give you how high the top of the cap should be above the SB.  I then write in pencil directly on the SB at that point the target height of the bridge with the cap.  I then plane the cap material to that target plus 1 mm and sand the cap to the final height.  Lay out the bridge pin array and go from there. 

I always pre-stress the board by inserting some wedges under the struts of the piano to "take out the slack" before I take the measurements.  .  

Original Message:
Sent: 9/16/2025 2:22:00 PM
From: David Love
Subject: RE: Downbearing Bridge Cap Thickness Tool

David H

I agree with that, but who said anything about reducing the height of the bridge root?  When I'm recapping a bridge I remove the cap which I do in one piece (each section), which is easy to do an old Steinway Bridge, leaving the root intact.  The method I have outlined is determining the thickness of the new cap, no more, no less.  

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320

Original Message:
Sent: 09-16-2025 09:53
From: David Hughes
Subject: Downbearing Bridge Cap Thickness Tool

Terry Farrell (Post #4),

In my opinion (and what do I know, really), a Steinway bridge root/trunk (as one example) is made to the "ideal" height at the factory. This vertically laminated member is strong/unyielding in its original height from end to end, with a cap glued atop that is just tall enough to accommodate the deepest union notches. If we reduce the root to accommodate a thicker cap, we weaken it. The cap material is flexible in its linear dimension; the bridge root is not, and there's a reason for that. The root supports the crown along the grain of the soundboard for the life of the instrument. In my rebuilding work, and again what the heck do I know, I never violated the height of the root. I was much happier "wasting" cap material than reducing the root. I know you use a vertically laminated cap, and perhaps this makes up for the loss (but you have introduced a glue joint that never existed at that elevation, and the root structure would be stronger without it, with continuous vertical grain top-to-bottom, methinks), but I have seen scads of rebuilt Steinway and Mason & Hamlin pianos over the last 45 years with significantly reduced roots and chunky quartersawn maple caps, and they distress me.

David G. Hughes, RPT

Baltimore Chapter

------------------------------
David Hughes RPT
Vintage Case Parts
Glyndon MD
(443) 522-2201

Original Message:
Sent: 09-16-2025 09:19
From: Terrence Farrell
Subject: Downbearing Bridge Cap Thickness Tool

That is very close to the way that I've always set my downbearing. The only difference in my method is that because I use laminated bridge caps and don't really want to be planing down the cap that I just made, what I do is use your method to plane down the bridge root so that after the uniform-thickness cap is added, I get the bridge height I want. When measuring the downbearing for root planing, I simply include a spacer the same thickness of the cap. This has always worked well for me.

Terry Farrell


Original Message:
Sent: 9/15/2025 2:31:00 PM
From: David Love
Subject: Downbearing Bridge Cap Thickness Tool

In a recent discussion with a colleague I was conveying my method of determining bridge cap thickness in advance of gluing on the new cap material.  This way I can plane the new cap to the proper thickness before gluing it on.  I find that easier, and more accurate, than the traditional method of gluing on an oversize (thickness) cap and then cutting slots in the top and then planing the bridge to the depth of those slots. 

The pictures below are pretty self-explanatory.  I've sent a suggestion to Mazzaglia that they produce something like this out of brass, like their other fine tools.  But you can make one of these out of wood easily enough.  I actually found a metal wedge on line which was exactly these dimension that I use for this purpose, adding the markings myself.  The width of the wedge corresponds to the average spacing between the bridge pins.   

Here's a link to the item I purchased recently after my original wooden wedge that I had made got damaged.  Bueyfolt 1/2" x 3/4" x 4" Flange Wedge, Zinc Plated Metal Flange Wedge Pipe Fitting Welding Tool, Strong Welding Wedge, Rust-Proof, Corrosion Resistant and Strong, Spreading Flanges Triangle Tool - Amazon.com 

Procedurally, you determine the distance bearing at the rear string rest by multiplying the length of the backscale by .0175 for each 1 degree of distance bearing that you want (.0175 is the sine of 1 degree).  I then use the Mazzaglia bearing gauges set on top of the rear string rest and lower the string until it rests on the gauge/string rest and then slide the wedge under the string until it just touches the string.  Read the thickness and that's the bridge cap thickness.  By adding the cap thickness to the bridge root height it will give you how high the top of the cap should be above the SB.  I then write in pencil directly on the SB at that point the target height of the bridge with the cap.  I then plane the cap material to that target plus 1 mm and sand the cap to the final height.  Lay out the bridge pin array and go from there. 

I always pre-stress the board by inserting some wedges under the struts of the piano to "take out the slack" before I take the measurements.  .  

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
------------------------------

Dave Conte:

On old Steinway bridges, and many others of that vintage, the cap is glued in with hide glue.  It will f release. I first carefully work a sharp blade just into the cap:root joint and then put a few drops of denatured alcohol onto the blade so it wicks into the joint.  You work slowly and carefully and the cap will start to separate. Work the blade slowly as it does  while adding drops of DA until you get enough of a gap to insert a thin wedge. Continue to insert the wedge further while adding drops of DA and eventually you can work the cap off in one piece. Caps are usually done in sections, one in each capo section and then one piece for the longer tenor section. The bass bridge is often uncapped, just a solid piece of wood, in which case I plane it down far enough to add a cap. 

I have some pictures somewhere. If I find then I'll post them. 

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
------------------------------

Original Message:
Sent: 09-17-2025 08:07
From: Dave Conte
Subject: Downbearing Bridge Cap Thickness Tool

Original Message:
Sent: 9/16/2025 2:22:00 PM
From: David Love
Subject: RE: Downbearing Bridge Cap Thickness Tool

David H

I agree with that, but who said anything about reducing the height of the bridge root?  When I'm recapping a bridge I remove the cap which I do in one piece (each section), which is easy to do an old Steinway Bridge, leaving the root intact.  The method I have outlined is determining the thickness of the new cap, no more, no less.  

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320

Original Message:
Sent: 09-16-2025 09:53
From: David Hughes
Subject: Downbearing Bridge Cap Thickness Tool

Terry Farrell (Post #4),

In my opinion (and what do I know, really), a Steinway bridge root/trunk (as one example) is made to the "ideal" height at the factory. This vertically laminated member is strong/unyielding in its original height from end to end, with a cap glued atop that is just tall enough to accommodate the deepest union notches. If we reduce the root to accommodate a thicker cap, we weaken it. The cap material is flexible in its linear dimension; the bridge root is not, and there's a reason for that. The root supports the crown along the grain of the soundboard for the life of the instrument. In my rebuilding work, and again what the heck do I know, I never violated the height of the root. I was much happier "wasting" cap material than reducing the root. I know you use a vertically laminated cap, and perhaps this makes up for the loss (but you have introduced a glue joint that never existed at that elevation, and the root structure would be stronger without it, with continuous vertical grain top-to-bottom, methinks), but I have seen scads of rebuilt Steinway and Mason & Hamlin pianos over the last 45 years with significantly reduced roots and chunky quartersawn maple caps, and they distress me.

David G. Hughes, RPT

Baltimore Chapter

------------------------------
David Hughes RPT
Vintage Case Parts
Glyndon MD
(443) 522-2201

Original Message:
Sent: 09-16-2025 09:19
From: Terrence Farrell
Subject: Downbearing Bridge Cap Thickness Tool

That is very close to the way that I've always set my downbearing. The only difference in my method is that because I use laminated bridge caps and don't really want to be planing down the cap that I just made, what I do is use your method to plane down the bridge root so that after the uniform-thickness cap is added, I get the bridge height I want. When measuring the downbearing for root planing, I simply include a spacer the same thickness of the cap. This has always worked well for me.

Terry Farrell


Original Message:
Sent: 9/15/2025 2:31:00 PM
From: David Love
Subject: Downbearing Bridge Cap Thickness Tool

In a recent discussion with a colleague I was conveying my method of determining bridge cap thickness in advance of gluing on the new cap material.  This way I can plane the new cap to the proper thickness before gluing it on.  I find that easier, and more accurate, than the traditional method of gluing on an oversize (thickness) cap and then cutting slots in the top and then planing the bridge to the depth of those slots. 

The pictures below are pretty self-explanatory.  I've sent a suggestion to Mazzaglia that they produce something like this out of brass, like their other fine tools.  But you can make one of these out of wood easily enough.  I actually found a metal wedge on line which was exactly these dimension that I use for this purpose, adding the markings myself.  The width of the wedge corresponds to the average spacing between the bridge pins.   

Here's a link to the item I purchased recently after my original wooden wedge that I had made got damaged.  Bueyfolt 1/2" x 3/4" x 4" Flange Wedge, Zinc Plated Metal Flange Wedge Pipe Fitting Welding Tool, Strong Welding Wedge, Rust-Proof, Corrosion Resistant and Strong, Spreading Flanges Triangle Tool - Amazon.com 

Procedurally, you determine the distance bearing at the rear string rest by multiplying the length of the backscale by .0175 for each 1 degree of distance bearing that you want (.0175 is the sine of 1 degree).  I then use the Mazzaglia bearing gauges set on top of the rear string rest and lower the string until it rests on the gauge/string rest and then slide the wedge under the string until it just touches the string.  Read the thickness and that's the bridge cap thickness.  By adding the cap thickness to the bridge root height it will give you how high the top of the cap should be above the SB.  I then write in pencil directly on the SB at that point the target height of the bridge with the cap.  I then plane the cap material to that target plus 1 mm and sand the cap to the final height.  Lay out the bridge pin array and go from there. 

I always pre-stress the board by inserting some wedges under the struts of the piano to "take out the slack" before I take the measurements.  .  

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
------------------------------

Original Message:
Sent: 9/17/2025 10:39:00 AM
From: David Love
Subject: RE: Downbearing Bridge Cap Thickness Tool

Dave Conte:

On old Steinway bridges, and many others of that vintage, the cap is glued in with hide glue.  It will f release. I first carefully work a sharp blade just into the cap:root joint and then put a few drops of denatured alcohol onto the blade so it wicks into the joint.  You work slowly and carefully and the cap will start to separate. Work the blade slowly as it does  while adding drops of DA until you get enough of a gap to insert a thin wedge. Continue to insert the wedge further while adding drops of DA and eventually you can work the cap off in one piece. Caps are usually done in sections, one in each capo section and then one piece for the longer tenor section. The bass bridge is often uncapped, just a solid piece of wood, in which case I plane it down far enough to add a cap. 

I have some pictures somewhere. If I find then I'll post them. 

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320

Original Message:
Sent: 09-17-2025 08:07
From: Dave Conte
Subject: Downbearing Bridge Cap Thickness Tool

Original Message:
Sent: 9/16/2025 2:22:00 PM
From: David Love
Subject: RE: Downbearing Bridge Cap Thickness Tool

David H

I agree with that, but who said anything about reducing the height of the bridge root?  When I'm recapping a bridge I remove the cap which I do in one piece (each section), which is easy to do an old Steinway Bridge, leaving the root intact.  The method I have outlined is determining the thickness of the new cap, no more, no less.  

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320

Original Message:
Sent: 09-16-2025 09:53
From: David Hughes
Subject: Downbearing Bridge Cap Thickness Tool

Terry Farrell (Post #4),

In my opinion (and what do I know, really), a Steinway bridge root/trunk (as one example) is made to the "ideal" height at the factory. This vertically laminated member is strong/unyielding in its original height from end to end, with a cap glued atop that is just tall enough to accommodate the deepest union notches. If we reduce the root to accommodate a thicker cap, we weaken it. The cap material is flexible in its linear dimension; the bridge root is not, and there's a reason for that. The root supports the crown along the grain of the soundboard for the life of the instrument. In my rebuilding work, and again what the heck do I know, I never violated the height of the root. I was much happier "wasting" cap material than reducing the root. I know you use a vertically laminated cap, and perhaps this makes up for the loss (but you have introduced a glue joint that never existed at that elevation, and the root structure would be stronger without it, with continuous vertical grain top-to-bottom, methinks), but I have seen scads of rebuilt Steinway and Mason & Hamlin pianos over the last 45 years with significantly reduced roots and chunky quartersawn maple caps, and they distress me.

David G. Hughes, RPT

Baltimore Chapter

------------------------------
David Hughes RPT
Vintage Case Parts
Glyndon MD
(443) 522-2201

Original Message:
Sent: 09-16-2025 09:19
From: Terrence Farrell
Subject: Downbearing Bridge Cap Thickness Tool

That is very close to the way that I've always set my downbearing. The only difference in my method is that because I use laminated bridge caps and don't really want to be planing down the cap that I just made, what I do is use your method to plane down the bridge root so that after the uniform-thickness cap is added, I get the bridge height I want. When measuring the downbearing for root planing, I simply include a spacer the same thickness of the cap. This has always worked well for me.

Terry Farrell


Original Message:
Sent: 9/15/2025 2:31:00 PM
From: David Love
Subject: Downbearing Bridge Cap Thickness Tool

In a recent discussion with a colleague I was conveying my method of determining bridge cap thickness in advance of gluing on the new cap material.  This way I can plane the new cap to the proper thickness before gluing it on.  I find that easier, and more accurate, than the traditional method of gluing on an oversize (thickness) cap and then cutting slots in the top and then planing the bridge to the depth of those slots. 

The pictures below are pretty self-explanatory.  I've sent a suggestion to Mazzaglia that they produce something like this out of brass, like their other fine tools.  But you can make one of these out of wood easily enough.  I actually found a metal wedge on line which was exactly these dimension that I use for this purpose, adding the markings myself.  The width of the wedge corresponds to the average spacing between the bridge pins.   

Here's a link to the item I purchased recently after my original wooden wedge that I had made got damaged.  Bueyfolt 1/2" x 3/4" x 4" Flange Wedge, Zinc Plated Metal Flange Wedge Pipe Fitting Welding Tool, Strong Welding Wedge, Rust-Proof, Corrosion Resistant and Strong, Spreading Flanges Triangle Tool - Amazon.com 

Procedurally, you determine the distance bearing at the rear string rest by multiplying the length of the backscale by .0175 for each 1 degree of distance bearing that you want (.0175 is the sine of 1 degree).  I then use the Mazzaglia bearing gauges set on top of the rear string rest and lower the string until it rests on the gauge/string rest and then slide the wedge under the string until it just touches the string.  Read the thickness and that's the bridge cap thickness.  By adding the cap thickness to the bridge root height it will give you how high the top of the cap should be above the SB.  I then write in pencil directly on the SB at that point the target height of the bridge with the cap.  I then plane the cap material to that target plus 1 mm and sand the cap to the final height.  Lay out the bridge pin array and go from there. 

I always pre-stress the board by inserting some wedges under the struts of the piano to "take out the slack" before I take the measurements.  .  

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
------------------------------

Dave C

Photos attached (having some trouble with this posting so let's see if this works).  There are other methods.  I don't use heat or steam, this seems to work just fine.  If I'm doing this in the piano I'm going to be refinishing the board and I do this before I strip the old finish so not too worried about the DA marring the finish.  

Original Message:
Sent: 9/17/2025 10:39:00 AM
From: David Love
Subject: RE: Downbearing Bridge Cap Thickness Tool

Dave Conte:

On old Steinway bridges, and many others of that vintage, the cap is glued in with hide glue.  It will f release. I first carefully work a sharp blade just into the cap:root joint and then put a few drops of denatured alcohol onto the blade so it wicks into the joint.  You work slowly and carefully and the cap will start to separate. Work the blade slowly as it does  while adding drops of DA until you get enough of a gap to insert a thin wedge. Continue to insert the wedge further while adding drops of DA and eventually you can work the cap off in one piece. Caps are usually done in sections, one in each capo section and then one piece for the longer tenor section. The bass bridge is often uncapped, just a solid piece of wood, in which case I plane it down far enough to add a cap. 

I have some pictures somewhere. If I find then I'll post them. 

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320

Original Message:
Sent: 09-17-2025 08:07
From: Dave Conte
Subject: Downbearing Bridge Cap Thickness Tool

Original Message:
Sent: 9/16/2025 2:22:00 PM
From: David Love
Subject: RE: Downbearing Bridge Cap Thickness Tool

David H

I agree with that, but who said anything about reducing the height of the bridge root?  When I'm recapping a bridge I remove the cap which I do in one piece (each section), which is easy to do an old Steinway Bridge, leaving the root intact.  The method I have outlined is determining the thickness of the new cap, no more, no less.  

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320

Original Message:
Sent: 09-16-2025 09:53
From: David Hughes
Subject: Downbearing Bridge Cap Thickness Tool

Terry Farrell (Post #4),

In my opinion (and what do I know, really), a Steinway bridge root/trunk (as one example) is made to the "ideal" height at the factory. This vertically laminated member is strong/unyielding in its original height from end to end, with a cap glued atop that is just tall enough to accommodate the deepest union notches. If we reduce the root to accommodate a thicker cap, we weaken it. The cap material is flexible in its linear dimension; the bridge root is not, and there's a reason for that. The root supports the crown along the grain of the soundboard for the life of the instrument. In my rebuilding work, and again what the heck do I know, I never violated the height of the root. I was much happier "wasting" cap material than reducing the root. I know you use a vertically laminated cap, and perhaps this makes up for the loss (but you have introduced a glue joint that never existed at that elevation, and the root structure would be stronger without it, with continuous vertical grain top-to-bottom, methinks), but I have seen scads of rebuilt Steinway and Mason & Hamlin pianos over the last 45 years with significantly reduced roots and chunky quartersawn maple caps, and they distress me.

David G. Hughes, RPT

Baltimore Chapter

------------------------------
David Hughes RPT
Vintage Case Parts
Glyndon MD
(443) 522-2201

Original Message:
Sent: 09-16-2025 09:19
From: Terrence Farrell
Subject: Downbearing Bridge Cap Thickness Tool

That is very close to the way that I've always set my downbearing. The only difference in my method is that because I use laminated bridge caps and don't really want to be planing down the cap that I just made, what I do is use your method to plane down the bridge root so that after the uniform-thickness cap is added, I get the bridge height I want. When measuring the downbearing for root planing, I simply include a spacer the same thickness of the cap. This has always worked well for me.

Terry Farrell


Original Message:
Sent: 9/15/2025 2:31:00 PM
From: David Love
Subject: Downbearing Bridge Cap Thickness Tool

In a recent discussion with a colleague I was conveying my method of determining bridge cap thickness in advance of gluing on the new cap material.  This way I can plane the new cap to the proper thickness before gluing it on.  I find that easier, and more accurate, than the traditional method of gluing on an oversize (thickness) cap and then cutting slots in the top and then planing the bridge to the depth of those slots. 

The pictures below are pretty self-explanatory.  I've sent a suggestion to Mazzaglia that they produce something like this out of brass, like their other fine tools.  But you can make one of these out of wood easily enough.  I actually found a metal wedge on line which was exactly these dimension that I use for this purpose, adding the markings myself.  The width of the wedge corresponds to the average spacing between the bridge pins.   

Here's a link to the item I purchased recently after my original wooden wedge that I had made got damaged.  Bueyfolt 1/2" x 3/4" x 4" Flange Wedge, Zinc Plated Metal Flange Wedge Pipe Fitting Welding Tool, Strong Welding Wedge, Rust-Proof, Corrosion Resistant and Strong, Spreading Flanges Triangle Tool - Amazon.com 

Procedurally, you determine the distance bearing at the rear string rest by multiplying the length of the backscale by .0175 for each 1 degree of distance bearing that you want (.0175 is the sine of 1 degree).  I then use the Mazzaglia bearing gauges set on top of the rear string rest and lower the string until it rests on the gauge/string rest and then slide the wedge under the string until it just touches the string.  Read the thickness and that's the bridge cap thickness.  By adding the cap thickness to the bridge root height it will give you how high the top of the cap should be above the SB.  I then write in pencil directly on the SB at that point the target height of the bridge with the cap.  I then plane the cap material to that target plus 1 mm and sand the cap to the final height.  Lay out the bridge pin array and go from there. 

I always pre-stress the board by inserting some wedges under the struts of the piano to "take out the slack" before I take the measurements.  .  

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
------------------------------

David, in the final picture, the bridge pin holes in the bass root don't seem to align at all with the cap. What am I missing here?

Dave C

Photos attached (having some trouble with this posting so let's see if this works).  There are other methods.  I don't use heat or steam, this seems to work just fine.  If I'm doing this in the piano I'm going to be refinishing the board and I do this before I strip the old finish so not too worried about the DA marring the finish.  

Original Message:
Sent: 9/17/2025 10:39:00 AM
From: David Love
Subject: RE: Downbearing Bridge Cap Thickness Tool

Dave Conte:

On old Steinway bridges, and many others of that vintage, the cap is glued in with hide glue.  It will f release. I first carefully work a sharp blade just into the cap:root joint and then put a few drops of denatured alcohol onto the blade so it wicks into the joint.  You work slowly and carefully and the cap will start to separate. Work the blade slowly as it does  while adding drops of DA until you get enough of a gap to insert a thin wedge. Continue to insert the wedge further while adding drops of DA and eventually you can work the cap off in one piece. Caps are usually done in sections, one in each capo section and then one piece for the longer tenor section. The bass bridge is often uncapped, just a solid piece of wood, in which case I plane it down far enough to add a cap. 

I have some pictures somewhere. If I find then I'll post them. 

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320

Original Message:
Sent: 09-17-2025 08:07
From: Dave Conte
Subject: Downbearing Bridge Cap Thickness Tool

Original Message:
Sent: 9/16/2025 2:22:00 PM
From: David Love
Subject: RE: Downbearing Bridge Cap Thickness Tool

David H

I agree with that, but who said anything about reducing the height of the bridge root?  When I'm recapping a bridge I remove the cap which I do in one piece (each section), which is easy to do an old Steinway Bridge, leaving the root intact.  The method I have outlined is determining the thickness of the new cap, no more, no less.  

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320

Original Message:
Sent: 09-16-2025 09:53
From: David Hughes
Subject: Downbearing Bridge Cap Thickness Tool

Terry Farrell (Post #4),

In my opinion (and what do I know, really), a Steinway bridge root/trunk (as one example) is made to the "ideal" height at the factory. This vertically laminated member is strong/unyielding in its original height from end to end, with a cap glued atop that is just tall enough to accommodate the deepest union notches. If we reduce the root to accommodate a thicker cap, we weaken it. The cap material is flexible in its linear dimension; the bridge root is not, and there's a reason for that. The root supports the crown along the grain of the soundboard for the life of the instrument. In my rebuilding work, and again what the heck do I know, I never violated the height of the root. I was much happier "wasting" cap material than reducing the root. I know you use a vertically laminated cap, and perhaps this makes up for the loss (but you have introduced a glue joint that never existed at that elevation, and the root structure would be stronger without it, with continuous vertical grain top-to-bottom, methinks), but I have seen scads of rebuilt Steinway and Mason & Hamlin pianos over the last 45 years with significantly reduced roots and chunky quartersawn maple caps, and they distress me.

David G. Hughes, RPT

Baltimore Chapter

------------------------------
David Hughes RPT
Vintage Case Parts
Glyndon MD
(443) 522-2201

Original Message:
Sent: 09-16-2025 09:19
From: Terrence Farrell
Subject: Downbearing Bridge Cap Thickness Tool

That is very close to the way that I've always set my downbearing. The only difference in my method is that because I use laminated bridge caps and don't really want to be planing down the cap that I just made, what I do is use your method to plane down the bridge root so that after the uniform-thickness cap is added, I get the bridge height I want. When measuring the downbearing for root planing, I simply include a spacer the same thickness of the cap. This has always worked well for me.

Terry Farrell


Original Message:
Sent: 9/15/2025 2:31:00 PM
From: David Love
Subject: Downbearing Bridge Cap Thickness Tool

In a recent discussion with a colleague I was conveying my method of determining bridge cap thickness in advance of gluing on the new cap material.  This way I can plane the new cap to the proper thickness before gluing it on.  I find that easier, and more accurate, than the traditional method of gluing on an oversize (thickness) cap and then cutting slots in the top and then planing the bridge to the depth of those slots. 

The pictures below are pretty self-explanatory.  I've sent a suggestion to Mazzaglia that they produce something like this out of brass, like their other fine tools.  But you can make one of these out of wood easily enough.  I actually found a metal wedge on line which was exactly these dimension that I use for this purpose, adding the markings myself.  The width of the wedge corresponds to the average spacing between the bridge pins.   

Here's a link to the item I purchased recently after my original wooden wedge that I had made got damaged.  Bueyfolt 1/2" x 3/4" x 4" Flange Wedge, Zinc Plated Metal Flange Wedge Pipe Fitting Welding Tool, Strong Welding Wedge, Rust-Proof, Corrosion Resistant and Strong, Spreading Flanges Triangle Tool - Amazon.com 

Procedurally, you determine the distance bearing at the rear string rest by multiplying the length of the backscale by .0175 for each 1 degree of distance bearing that you want (.0175 is the sine of 1 degree).  I then use the Mazzaglia bearing gauges set on top of the rear string rest and lower the string until it rests on the gauge/string rest and then slide the wedge under the string until it just touches the string.  Read the thickness and that's the bridge cap thickness.  By adding the cap thickness to the bridge root height it will give you how high the top of the cap should be above the SB.  I then write in pencil directly on the SB at that point the target height of the bridge with the cap.  I then plane the cap material to that target plus 1 mm and sand the cap to the final height.  Lay out the bridge pin array and go from there. 

I always pre-stress the board by inserting some wedges under the struts of the piano to "take out the slack" before I take the measurements.  .  

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
------------------------------

Dave C

Photos attached (having some trouble with this posting so let's see if this works).  There are other methods.  I don't use heat or steam, this seems to work just fine.  If I'm doing this in the piano I'm going to be refinishing the board and I do this before I strip the old finish so not too worried about the DA marring the finish.  

Original Message:
Sent: 9/17/2025 10:39:00 AM
From: David Love
Subject: RE: Downbearing Bridge Cap Thickness Tool

Dave Conte:

On old Steinway bridges, and many others of that vintage, the cap is glued in with hide glue.  It will f release. I first carefully work a sharp blade just into the cap:root joint and then put a few drops of denatured alcohol onto the blade so it wicks into the joint.  You work slowly and carefully and the cap will start to separate. Work the blade slowly as it does  while adding drops of DA until you get enough of a gap to insert a thin wedge. Continue to insert the wedge further while adding drops of DA and eventually you can work the cap off in one piece. Caps are usually done in sections, one in each capo section and then one piece for the longer tenor section. The bass bridge is often uncapped, just a solid piece of wood, in which case I plane it down far enough to add a cap. 

I have some pictures somewhere. If I find then I'll post them. 

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320

Original Message:
Sent: 09-17-2025 08:07
From: Dave Conte
Subject: Downbearing Bridge Cap Thickness Tool

Original Message:
Sent: 9/16/2025 2:22:00 PM
From: David Love
Subject: RE: Downbearing Bridge Cap Thickness Tool

David H

I agree with that, but who said anything about reducing the height of the bridge root?  When I'm recapping a bridge I remove the cap which I do in one piece (each section), which is easy to do an old Steinway Bridge, leaving the root intact.  The method I have outlined is determining the thickness of the new cap, no more, no less.  

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320

Original Message:
Sent: 09-16-2025 09:53
From: David Hughes
Subject: Downbearing Bridge Cap Thickness Tool

Terry Farrell (Post #4),

In my opinion (and what do I know, really), a Steinway bridge root/trunk (as one example) is made to the "ideal" height at the factory. This vertically laminated member is strong/unyielding in its original height from end to end, with a cap glued atop that is just tall enough to accommodate the deepest union notches. If we reduce the root to accommodate a thicker cap, we weaken it. The cap material is flexible in its linear dimension; the bridge root is not, and there's a reason for that. The root supports the crown along the grain of the soundboard for the life of the instrument. In my rebuilding work, and again what the heck do I know, I never violated the height of the root. I was much happier "wasting" cap material than reducing the root. I know you use a vertically laminated cap, and perhaps this makes up for the loss (but you have introduced a glue joint that never existed at that elevation, and the root structure would be stronger without it, with continuous vertical grain top-to-bottom, methinks), but I have seen scads of rebuilt Steinway and Mason & Hamlin pianos over the last 45 years with significantly reduced roots and chunky quartersawn maple caps, and they distress me.

David G. Hughes, RPT

Baltimore Chapter

------------------------------
David Hughes RPT
Vintage Case Parts
Glyndon MD
(443) 522-2201

Original Message:
Sent: 09-16-2025 09:19
From: Terrence Farrell
Subject: Downbearing Bridge Cap Thickness Tool

That is very close to the way that I've always set my downbearing. The only difference in my method is that because I use laminated bridge caps and don't really want to be planing down the cap that I just made, what I do is use your method to plane down the bridge root so that after the uniform-thickness cap is added, I get the bridge height I want. When measuring the downbearing for root planing, I simply include a spacer the same thickness of the cap. This has always worked well for me.

Terry Farrell


Original Message:
Sent: 9/15/2025 2:31:00 PM
From: David Love
Subject: Downbearing Bridge Cap Thickness Tool

In a recent discussion with a colleague I was conveying my method of determining bridge cap thickness in advance of gluing on the new cap material.  This way I can plane the new cap to the proper thickness before gluing it on.  I find that easier, and more accurate, than the traditional method of gluing on an oversize (thickness) cap and then cutting slots in the top and then planing the bridge to the depth of those slots. 

The pictures below are pretty self-explanatory.  I've sent a suggestion to Mazzaglia that they produce something like this out of brass, like their other fine tools.  But you can make one of these out of wood easily enough.  I actually found a metal wedge on line which was exactly these dimension that I use for this purpose, adding the markings myself.  The width of the wedge corresponds to the average spacing between the bridge pins.   

Here's a link to the item I purchased recently after my original wooden wedge that I had made got damaged.  Bueyfolt 1/2" x 3/4" x 4" Flange Wedge, Zinc Plated Metal Flange Wedge Pipe Fitting Welding Tool, Strong Welding Wedge, Rust-Proof, Corrosion Resistant and Strong, Spreading Flanges Triangle Tool - Amazon.com 

Procedurally, you determine the distance bearing at the rear string rest by multiplying the length of the backscale by .0175 for each 1 degree of distance bearing that you want (.0175 is the sine of 1 degree).  I then use the Mazzaglia bearing gauges set on top of the rear string rest and lower the string until it rests on the gauge/string rest and then slide the wedge under the string until it just touches the string.  Read the thickness and that's the bridge cap thickness.  By adding the cap thickness to the bridge root height it will give you how high the top of the cap should be above the SB.  I then write in pencil directly on the SB at that point the target height of the bridge with the cap.  I then plane the cap material to that target plus 1 mm and sand the cap to the final height.  Lay out the bridge pin array and go from there. 

I always pre-stress the board by inserting some wedges under the struts of the piano to "take out the slack" before I take the measurements.  .  

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
------------------------------

DLOVE,

A quick question. I noticed in the pictures you presented that it looks like the grain direction of the panel has been changed. i was wondering what the reasoning was for changing the angle?  I was taught(DF) that the correct angle does two things 1) increases the energy of the board, and avoids a slight weakness. I was told that the longest board should go from corner to corner, maybe that advice stinks, i dont know.

xoxo

chris

------------------------------
On the page, it looked....nothing.
The beginning, simple, almost comic.
Just a pulse - bassoons, basset horns, like a rusty squeezebox. And then suddenly, high above it..an oboe, hanging there unwavering, until a clarinet sweetened it into a phrase of such delight.
This was no composition by a performing monkey!!

865-986-7720 (text only please)

Original Message:
Sent: 09-17-2025 11:38
From: David Love
Subject: Downbearing Bridge Cap Thickness Tool

Dave C

Photos attached (having some trouble with this posting so let's see if this works).  There are other methods.  I don't use heat or steam, this seems to work just fine.  If I'm doing this in the piano I'm going to be refinishing the board and I do this before I strip the old finish so not too worried about the DA marring the finish.  

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320

Original Message:
Sent: 09-17-2025 10:49
From: Dave Conte
Subject: Downbearing Bridge Cap Thickness Tool

Original Message:
Sent: 9/17/2025 10:39:00 AM
From: David Love
Subject: RE: Downbearing Bridge Cap Thickness Tool

Dave Conte:

On old Steinway bridges, and many others of that vintage, the cap is glued in with hide glue.  It will f release. I first carefully work a sharp blade just into the cap:root joint and then put a few drops of denatured alcohol onto the blade so it wicks into the joint.  You work slowly and carefully and the cap will start to separate. Work the blade slowly as it does  while adding drops of DA until you get enough of a gap to insert a thin wedge. Continue to insert the wedge further while adding drops of DA and eventually you can work the cap off in one piece. Caps are usually done in sections, one in each capo section and then one piece for the longer tenor section. The bass bridge is often uncapped, just a solid piece of wood, in which case I plane it down far enough to add a cap. 

I have some pictures somewhere. If I find then I'll post them. 

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320

Original Message:
Sent: 09-17-2025 08:07
From: Dave Conte
Subject: Downbearing Bridge Cap Thickness Tool

Original Message:
Sent: 9/16/2025 2:22:00 PM
From: David Love
Subject: RE: Downbearing Bridge Cap Thickness Tool

David H

I agree with that, but who said anything about reducing the height of the bridge root?  When I'm recapping a bridge I remove the cap which I do in one piece (each section), which is easy to do an old Steinway Bridge, leaving the root intact.  The method I have outlined is determining the thickness of the new cap, no more, no less.  

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320

Original Message:
Sent: 09-16-2025 09:53
From: David Hughes
Subject: Downbearing Bridge Cap Thickness Tool

Terry Farrell (Post #4),

In my opinion (and what do I know, really), a Steinway bridge root/trunk (as one example) is made to the "ideal" height at the factory. This vertically laminated member is strong/unyielding in its original height from end to end, with a cap glued atop that is just tall enough to accommodate the deepest union notches. If we reduce the root to accommodate a thicker cap, we weaken it. The cap material is flexible in its linear dimension; the bridge root is not, and there's a reason for that. The root supports the crown along the grain of the soundboard for the life of the instrument. In my rebuilding work, and again what the heck do I know, I never violated the height of the root. I was much happier "wasting" cap material than reducing the root. I know you use a vertically laminated cap, and perhaps this makes up for the loss (but you have introduced a glue joint that never existed at that elevation, and the root structure would be stronger without it, with continuous vertical grain top-to-bottom, methinks), but I have seen scads of rebuilt Steinway and Mason & Hamlin pianos over the last 45 years with significantly reduced roots and chunky quartersawn maple caps, and they distress me.

David G. Hughes, RPT

Baltimore Chapter

------------------------------
David Hughes RPT
Vintage Case Parts
Glyndon MD
(443) 522-2201

Original Message:
Sent: 09-16-2025 09:19
From: Terrence Farrell
Subject: Downbearing Bridge Cap Thickness Tool

That is very close to the way that I've always set my downbearing. The only difference in my method is that because I use laminated bridge caps and don't really want to be planing down the cap that I just made, what I do is use your method to plane down the bridge root so that after the uniform-thickness cap is added, I get the bridge height I want. When measuring the downbearing for root planing, I simply include a spacer the same thickness of the cap. This has always worked well for me.

Terry Farrell


Original Message:
Sent: 9/15/2025 2:31:00 PM
From: David Love
Subject: Downbearing Bridge Cap Thickness Tool

In a recent discussion with a colleague I was conveying my method of determining bridge cap thickness in advance of gluing on the new cap material.  This way I can plane the new cap to the proper thickness before gluing it on.  I find that easier, and more accurate, than the traditional method of gluing on an oversize (thickness) cap and then cutting slots in the top and then planing the bridge to the depth of those slots. 

The pictures below are pretty self-explanatory.  I've sent a suggestion to Mazzaglia that they produce something like this out of brass, like their other fine tools.  But you can make one of these out of wood easily enough.  I actually found a metal wedge on line which was exactly these dimension that I use for this purpose, adding the markings myself.  The width of the wedge corresponds to the average spacing between the bridge pins.   

Here's a link to the item I purchased recently after my original wooden wedge that I had made got damaged.  Bueyfolt 1/2" x 3/4" x 4" Flange Wedge, Zinc Plated Metal Flange Wedge Pipe Fitting Welding Tool, Strong Welding Wedge, Rust-Proof, Corrosion Resistant and Strong, Spreading Flanges Triangle Tool - Amazon.com 

Procedurally, you determine the distance bearing at the rear string rest by multiplying the length of the backscale by .0175 for each 1 degree of distance bearing that you want (.0175 is the sine of 1 degree).  I then use the Mazzaglia bearing gauges set on top of the rear string rest and lower the string until it rests on the gauge/string rest and then slide the wedge under the string until it just touches the string.  Read the thickness and that's the bridge cap thickness.  By adding the cap thickness to the bridge root height it will give you how high the top of the cap should be above the SB.  I then write in pencil directly on the SB at that point the target height of the bridge with the cap.  I then plane the cap material to that target plus 1 mm and sand the cap to the final height.  Lay out the bridge pin array and go from there. 

I always pre-stress the board by inserting some wedges under the struts of the piano to "take out the slack" before I take the measurements.  .  

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
------------------------------

Original Message:
Sent: 9/17/2025 10:39:00 AM
From: David Love
Subject: RE: Downbearing Bridge Cap Thickness Tool

Dave Conte:

On old Steinway bridges, and many others of that vintage, the cap is glued in with hide glue.  It will f release. I first carefully work a sharp blade just into the cap:root joint and then put a few drops of denatured alcohol onto the blade so it wicks into the joint.  You work slowly and carefully and the cap will start to separate. Work the blade slowly as it does  while adding drops of DA until you get enough of a gap to insert a thin wedge. Continue to insert the wedge further while adding drops of DA and eventually you can work the cap off in one piece. Caps are usually done in sections, one in each capo section and then one piece for the longer tenor section. The bass bridge is often uncapped, just a solid piece of wood, in which case I plane it down far enough to add a cap. 

I have some pictures somewhere. If I find then I'll post them. 

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320

Original Message:
Sent: 09-17-2025 08:07
From: Dave Conte
Subject: Downbearing Bridge Cap Thickness Tool

Original Message:
Sent: 9/16/2025 2:22:00 PM
From: David Love
Subject: RE: Downbearing Bridge Cap Thickness Tool

David H

I agree with that, but who said anything about reducing the height of the bridge root?  When I'm recapping a bridge I remove the cap which I do in one piece (each section), which is easy to do an old Steinway Bridge, leaving the root intact.  The method I have outlined is determining the thickness of the new cap, no more, no less.  

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320

Original Message:
Sent: 09-16-2025 09:53
From: David Hughes
Subject: Downbearing Bridge Cap Thickness Tool

Terry Farrell (Post #4),

In my opinion (and what do I know, really), a Steinway bridge root/trunk (as one example) is made to the "ideal" height at the factory. This vertically laminated member is strong/unyielding in its original height from end to end, with a cap glued atop that is just tall enough to accommodate the deepest union notches. If we reduce the root to accommodate a thicker cap, we weaken it. The cap material is flexible in its linear dimension; the bridge root is not, and there's a reason for that. The root supports the crown along the grain of the soundboard for the life of the instrument. In my rebuilding work, and again what the heck do I know, I never violated the height of the root. I was much happier "wasting" cap material than reducing the root. I know you use a vertically laminated cap, and perhaps this makes up for the loss (but you have introduced a glue joint that never existed at that elevation, and the root structure would be stronger without it, with continuous vertical grain top-to-bottom, methinks), but I have seen scads of rebuilt Steinway and Mason & Hamlin pianos over the last 45 years with significantly reduced roots and chunky quartersawn maple caps, and they distress me.

David G. Hughes, RPT

Baltimore Chapter

------------------------------
David Hughes RPT
Vintage Case Parts
Glyndon MD
(443) 522-2201

Original Message:
Sent: 09-16-2025 09:19
From: Terrence Farrell
Subject: Downbearing Bridge Cap Thickness Tool

That is very close to the way that I've always set my downbearing. The only difference in my method is that because I use laminated bridge caps and don't really want to be planing down the cap that I just made, what I do is use your method to plane down the bridge root so that after the uniform-thickness cap is added, I get the bridge height I want. When measuring the downbearing for root planing, I simply include a spacer the same thickness of the cap. This has always worked well for me.

Terry Farrell


Original Message:
Sent: 9/15/2025 2:31:00 PM
From: David Love
Subject: Downbearing Bridge Cap Thickness Tool

In a recent discussion with a colleague I was conveying my method of determining bridge cap thickness in advance of gluing on the new cap material.  This way I can plane the new cap to the proper thickness before gluing it on.  I find that easier, and more accurate, than the traditional method of gluing on an oversize (thickness) cap and then cutting slots in the top and then planing the bridge to the depth of those slots. 

The pictures below are pretty self-explanatory.  I've sent a suggestion to Mazzaglia that they produce something like this out of brass, like their other fine tools.  But you can make one of these out of wood easily enough.  I actually found a metal wedge on line which was exactly these dimension that I use for this purpose, adding the markings myself.  The width of the wedge corresponds to the average spacing between the bridge pins.   

Here's a link to the item I purchased recently after my original wooden wedge that I had made got damaged.  Bueyfolt 1/2" x 3/4" x 4" Flange Wedge, Zinc Plated Metal Flange Wedge Pipe Fitting Welding Tool, Strong Welding Wedge, Rust-Proof, Corrosion Resistant and Strong, Spreading Flanges Triangle Tool - Amazon.com 

Procedurally, you determine the distance bearing at the rear string rest by multiplying the length of the backscale by .0175 for each 1 degree of distance bearing that you want (.0175 is the sine of 1 degree).  I then use the Mazzaglia bearing gauges set on top of the rear string rest and lower the string until it rests on the gauge/string rest and then slide the wedge under the string until it just touches the string.  Read the thickness and that's the bridge cap thickness.  By adding the cap thickness to the bridge root height it will give you how high the top of the cap should be above the SB.  I then write in pencil directly on the SB at that point the target height of the bridge with the cap.  I then plane the cap material to that target plus 1 mm and sand the cap to the final height.  Lay out the bridge pin array and go from there. 

I always pre-stress the board by inserting some wedges under the struts of the piano to "take out the slack" before I take the measurements.  .  

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
------------------------------

Terry Farrell (Post #4),

In my opinion (and what do I know, really), a Steinway bridge root/trunk (as one example) is made to the "ideal" height at the factory. This vertically laminated member is strong/unyielding in its original height from end to end, with a cap glued atop that is just tall enough to accommodate the deepest union notches. If we reduce the root to accommodate a thicker cap, we weaken it. The cap material is flexible in its linear dimension; the bridge root is not, and there's a reason for that. The root supports the crown along the grain of the soundboard for the life of the instrument. In my rebuilding work, and again what the heck do I know, I never violated the height of the root. I was much happier "wasting" cap material than reducing the root. I know you use a vertically laminated cap, and perhaps this makes up for the loss (but you have introduced a glue joint that never existed at that elevation, and the root structure would be stronger without it, with continuous vertical grain top-to-bottom, methinks), but I have seen scads of rebuilt Steinway and Mason & Hamlin pianos over the last 45 years with significantly reduced roots and chunky quartersawn maple caps, and they distress me.

David G. Hughes, RPT

Baltimore Chapter

In a recent discussion with a colleague I was conveying my method of determining bridge cap thickness in advance of gluing on the new cap material.  This way I can plane the new cap to the proper thickness before gluing it on.  I find that easier, and more accurate, than the traditional method of gluing on an oversize (thickness) cap and then cutting slots in the top and then planing the bridge to the depth of those slots. 

The pictures below are pretty self-explanatory.  I've sent a suggestion to Mazzaglia that they produce something like this out of brass, like their other fine tools.  But you can make one of these out of wood easily enough.  I actually found a metal wedge on line which was exactly these dimension that I use for this purpose, adding the markings myself.  The width of the wedge corresponds to the average spacing between the bridge pins.   

Here's a link to the item I purchased recently after my original wooden wedge that I had made got damaged.  Bueyfolt 1/2" x 3/4" x 4" Flange Wedge, Zinc Plated Metal Flange Wedge Pipe Fitting Welding Tool, Strong Welding Wedge, Rust-Proof, Corrosion Resistant and Strong, Spreading Flanges Triangle Tool - Amazon.com 

Procedurally, you determine the distance bearing at the rear string rest by multiplying the length of the backscale by .0175 for each 1 degree of distance bearing that you want (.0175 is the sine of 1 degree).  I then use the Mazzaglia bearing gauges set on top of the rear string rest and lower the string until it rests on the gauge/string rest and then slide the wedge under the string until it just touches the string.  Read the thickness and that's the bridge cap thickness.  By adding the cap thickness to the bridge root height it will give you how high the top of the cap should be above the SB.  I then write in pencil directly on the SB at that point the target height of the bridge with the cap.  I then plane the cap material to that target plus 1 mm and sand the cap to the final height.  Lay out the bridge pin array and go from there. 

I always pre-stress the board by inserting some wedges under the struts of the piano to "take out the slack" before I take the measurements.  .  

The only thing I would say to that is that Terry is replacing caps with laminated caps and I've seen delignit, or similar, used as a bridge cap material on many pianos and I can't say that I detected any problem with crown stability as a result--hard to know though. I would thin that the laminate would be somewhat stiffer than a plain, thin maple cap. But I've never done any research on it to determine if the modulus is different there. 

I think there's another question implied here which is just how much does the bridge function to support crown? I would think not very much other than its function as another beam that spans the ribs and therefore distributes the load across the ribs to some degree.  But it's a good question. 

The other question is, are the vertical laminations used in a normal Steinway bridge root there for strength, or is that the only reasonable way to make a curved bridge and in terms of functionality and strength, the vertical laminations don't really make that much difference. I don't know the answer.  There are certainly some  benefits in having a vertically laminated bridge root, especially when it comes to removing the old cap. 

Terry Farrell (Post #4),

In my opinion (and what do I know, really), a Steinway bridge root/trunk (as one example) is made to the "ideal" height at the factory. This vertically laminated member is strong/unyielding in its original height from end to end, with a cap glued atop that is just tall enough to accommodate the deepest union notches. If we reduce the root to accommodate a thicker cap, we weaken it. The cap material is flexible in its linear dimension; the bridge root is not, and there's a reason for that. The root supports the crown along the grain of the soundboard for the life of the instrument. In my rebuilding work, and again what the heck do I know, I never violated the height of the root. I was much happier "wasting" cap material than reducing the root. I know you use a vertically laminated cap, and perhaps this makes up for the loss (but you have introduced a glue joint that never existed at that elevation, and the root structure would be stronger without it, with continuous vertical grain top-to-bottom, methinks), but I have seen scads of rebuilt Steinway and Mason & Hamlin pianos over the last 45 years with significantly reduced roots and chunky quartersawn maple caps, and they distress me.

David G. Hughes, RPT

Baltimore Chapter

In a recent discussion with a colleague I was conveying my method of determining bridge cap thickness in advance of gluing on the new cap material.  This way I can plane the new cap to the proper thickness before gluing it on.  I find that easier, and more accurate, than the traditional method of gluing on an oversize (thickness) cap and then cutting slots in the top and then planing the bridge to the depth of those slots. 

The pictures below are pretty self-explanatory.  I've sent a suggestion to Mazzaglia that they produce something like this out of brass, like their other fine tools.  But you can make one of these out of wood easily enough.  I actually found a metal wedge on line which was exactly these dimension that I use for this purpose, adding the markings myself.  The width of the wedge corresponds to the average spacing between the bridge pins.   

Here's a link to the item I purchased recently after my original wooden wedge that I had made got damaged.  Bueyfolt 1/2" x 3/4" x 4" Flange Wedge, Zinc Plated Metal Flange Wedge Pipe Fitting Welding Tool, Strong Welding Wedge, Rust-Proof, Corrosion Resistant and Strong, Spreading Flanges Triangle Tool - Amazon.com 

Procedurally, you determine the distance bearing at the rear string rest by multiplying the length of the backscale by .0175 for each 1 degree of distance bearing that you want (.0175 is the sine of 1 degree).  I then use the Mazzaglia bearing gauges set on top of the rear string rest and lower the string until it rests on the gauge/string rest and then slide the wedge under the string until it just touches the string.  Read the thickness and that's the bridge cap thickness.  By adding the cap thickness to the bridge root height it will give you how high the top of the cap should be above the SB.  I then write in pencil directly on the SB at that point the target height of the bridge with the cap.  I then plane the cap material to that target plus 1 mm and sand the cap to the final height.  Lay out the bridge pin array and go from there. 

I always pre-stress the board by inserting some wedges under the struts of the piano to "take out the slack" before I take the measurements.  .  

David Love - it's my understanding that the acoustic energy travels faster along the grain than across or tangentially. With 90 degree laminations it would follow that around 50% of the laminations would be vertical. If this is true, bridge caps would somewhat slow down the transmission and laminated caps would further retard it. 

The only thing I would say to that is that Terry is replacing caps with laminated caps and I've seen delignit, or similar, used as a bridge cap material on many pianos and I can't say that I detected any problem with crown stability as a result--hard to know though. I would thin that the laminate would be somewhat stiffer than a plain, thin maple cap. But I've never done any research on it to determine if the modulus is different there. 

I think there's another question implied here which is just how much does the bridge function to support crown? I would think not very much other than its function as another beam that spans the ribs and therefore distributes the load across the ribs to some degree.  But it's a good question. 

The other question is, are the vertical laminations used in a normal Steinway bridge root there for strength, or is that the only reasonable way to make a curved bridge and in terms of functionality and strength, the vertical laminations don't really make that much difference. I don't know the answer.  There are certainly some  benefits in having a vertically laminated bridge root, especially when it comes to removing the old cap. 

Terry Farrell (Post #4),

In my opinion (and what do I know, really), a Steinway bridge root/trunk (as one example) is made to the "ideal" height at the factory. This vertically laminated member is strong/unyielding in its original height from end to end, with a cap glued atop that is just tall enough to accommodate the deepest union notches. If we reduce the root to accommodate a thicker cap, we weaken it. The cap material is flexible in its linear dimension; the bridge root is not, and there's a reason for that. The root supports the crown along the grain of the soundboard for the life of the instrument. In my rebuilding work, and again what the heck do I know, I never violated the height of the root. I was much happier "wasting" cap material than reducing the root. I know you use a vertically laminated cap, and perhaps this makes up for the loss (but you have introduced a glue joint that never existed at that elevation, and the root structure would be stronger without it, with continuous vertical grain top-to-bottom, methinks), but I have seen scads of rebuilt Steinway and Mason & Hamlin pianos over the last 45 years with significantly reduced roots and chunky quartersawn maple caps, and they distress me.

David G. Hughes, RPT

Baltimore Chapter

In a recent discussion with a colleague I was conveying my method of determining bridge cap thickness in advance of gluing on the new cap material.  This way I can plane the new cap to the proper thickness before gluing it on.  I find that easier, and more accurate, than the traditional method of gluing on an oversize (thickness) cap and then cutting slots in the top and then planing the bridge to the depth of those slots. 

The pictures below are pretty self-explanatory.  I've sent a suggestion to Mazzaglia that they produce something like this out of brass, like their other fine tools.  But you can make one of these out of wood easily enough.  I actually found a metal wedge on line which was exactly these dimension that I use for this purpose, adding the markings myself.  The width of the wedge corresponds to the average spacing between the bridge pins.   

Here's a link to the item I purchased recently after my original wooden wedge that I had made got damaged.  Bueyfolt 1/2" x 3/4" x 4" Flange Wedge, Zinc Plated Metal Flange Wedge Pipe Fitting Welding Tool, Strong Welding Wedge, Rust-Proof, Corrosion Resistant and Strong, Spreading Flanges Triangle Tool - Amazon.com 

Procedurally, you determine the distance bearing at the rear string rest by multiplying the length of the backscale by .0175 for each 1 degree of distance bearing that you want (.0175 is the sine of 1 degree).  I then use the Mazzaglia bearing gauges set on top of the rear string rest and lower the string until it rests on the gauge/string rest and then slide the wedge under the string until it just touches the string.  Read the thickness and that's the bridge cap thickness.  By adding the cap thickness to the bridge root height it will give you how high the top of the cap should be above the SB.  I then write in pencil directly on the SB at that point the target height of the bridge with the cap.  I then plane the cap material to that target plus 1 mm and sand the cap to the final height.  Lay out the bridge pin array and go from there. 

I always pre-stress the board by inserting some wedges under the struts of the piano to "take out the slack" before I take the measurements.  .  

Terry Farrell (Post #4),

In my opinion (and what do I know, really), a Steinway bridge root/trunk (as one example) is made to the "ideal" height at the factory. This vertically laminated member is strong/unyielding in its original height from end to end, with a cap glued atop that is just tall enough to accommodate the deepest union notches. If we reduce the root to accommodate a thicker cap, we weaken it. The cap material is flexible in its linear dimension; the bridge root is not, and there's a reason for that. The root supports the crown along the grain of the soundboard for the life of the instrument. In my rebuilding work, and again what the heck do I know, I never violated the height of the root. I was much happier "wasting" cap material than reducing the root. I know you use a vertically laminated cap, and perhaps this makes up for the loss (but you have introduced a glue joint that never existed at that elevation, and the root structure would be stronger without it, with continuous vertical grain top-to-bottom, methinks), but I have seen scads of rebuilt Steinway and Mason & Hamlin pianos over the last 45 years with significantly reduced roots and chunky quartersawn maple caps, and they distress me.

David G. Hughes, RPT

Baltimore Chapter

In a recent discussion with a colleague I was conveying my method of determining bridge cap thickness in advance of gluing on the new cap material.  This way I can plane the new cap to the proper thickness before gluing it on.  I find that easier, and more accurate, than the traditional method of gluing on an oversize (thickness) cap and then cutting slots in the top and then planing the bridge to the depth of those slots. 

The pictures below are pretty self-explanatory.  I've sent a suggestion to Mazzaglia that they produce something like this out of brass, like their other fine tools.  But you can make one of these out of wood easily enough.  I actually found a metal wedge on line which was exactly these dimension that I use for this purpose, adding the markings myself.  The width of the wedge corresponds to the average spacing between the bridge pins.   

Here's a link to the item I purchased recently after my original wooden wedge that I had made got damaged.  Bueyfolt 1/2" x 3/4" x 4" Flange Wedge, Zinc Plated Metal Flange Wedge Pipe Fitting Welding Tool, Strong Welding Wedge, Rust-Proof, Corrosion Resistant and Strong, Spreading Flanges Triangle Tool - Amazon.com 

Procedurally, you determine the distance bearing at the rear string rest by multiplying the length of the backscale by .0175 for each 1 degree of distance bearing that you want (.0175 is the sine of 1 degree).  I then use the Mazzaglia bearing gauges set on top of the rear string rest and lower the string until it rests on the gauge/string rest and then slide the wedge under the string until it just touches the string.  Read the thickness and that's the bridge cap thickness.  By adding the cap thickness to the bridge root height it will give you how high the top of the cap should be above the SB.  I then write in pencil directly on the SB at that point the target height of the bridge with the cap.  I then plane the cap material to that target plus 1 mm and sand the cap to the final height.  Lay out the bridge pin array and go from there. 

I always pre-stress the board by inserting some wedges under the struts of the piano to "take out the slack" before I take the measurements.  .  

David:

     Your wise response is spot on.  We should strive to respect the original bridge root height and cap thickness.  What to do when bridge root is in bad shape

as occurs sometimes in Steinway uprights that used maple/mahoghany bridge roots. Plane down root and use a thick cap?

Terry Farrell (Post #4),

In my opinion (and what do I know, really), a Steinway bridge root/trunk (as one example) is made to the "ideal" height at the factory. This vertically laminated member is strong/unyielding in its original height from end to end, with a cap glued atop that is just tall enough to accommodate the deepest union notches. If we reduce the root to accommodate a thicker cap, we weaken it. The cap material is flexible in its linear dimension; the bridge root is not, and there's a reason for that. The root supports the crown along the grain of the soundboard for the life of the instrument. In my rebuilding work, and again what the heck do I know, I never violated the height of the root. I was much happier "wasting" cap material than reducing the root. I know you use a vertically laminated cap, and perhaps this makes up for the loss (but you have introduced a glue joint that never existed at that elevation, and the root structure would be stronger without it, with continuous vertical grain top-to-bottom, methinks), but I have seen scads of rebuilt Steinway and Mason & Hamlin pianos over the last 45 years with significantly reduced roots and chunky quartersawn maple caps, and they distress me.

David G. Hughes, RPT

Baltimore Chapter

In a recent discussion with a colleague I was conveying my method of determining bridge cap thickness in advance of gluing on the new cap material.  This way I can plane the new cap to the proper thickness before gluing it on.  I find that easier, and more accurate, than the traditional method of gluing on an oversize (thickness) cap and then cutting slots in the top and then planing the bridge to the depth of those slots. 

The pictures below are pretty self-explanatory.  I've sent a suggestion to Mazzaglia that they produce something like this out of brass, like their other fine tools.  But you can make one of these out of wood easily enough.  I actually found a metal wedge on line which was exactly these dimension that I use for this purpose, adding the markings myself.  The width of the wedge corresponds to the average spacing between the bridge pins.   

Here's a link to the item I purchased recently after my original wooden wedge that I had made got damaged.  Bueyfolt 1/2" x 3/4" x 4" Flange Wedge, Zinc Plated Metal Flange Wedge Pipe Fitting Welding Tool, Strong Welding Wedge, Rust-Proof, Corrosion Resistant and Strong, Spreading Flanges Triangle Tool - Amazon.com 

Procedurally, you determine the distance bearing at the rear string rest by multiplying the length of the backscale by .0175 for each 1 degree of distance bearing that you want (.0175 is the sine of 1 degree).  I then use the Mazzaglia bearing gauges set on top of the rear string rest and lower the string until it rests on the gauge/string rest and then slide the wedge under the string until it just touches the string.  Read the thickness and that's the bridge cap thickness.  By adding the cap thickness to the bridge root height it will give you how high the top of the cap should be above the SB.  I then write in pencil directly on the SB at that point the target height of the bridge with the cap.  I then plane the cap material to that target plus 1 mm and sand the cap to the final height.  Lay out the bridge pin array and go from there. 

I always pre-stress the board by inserting some wedges under the struts of the piano to "take out the slack" before I take the measurements.  .  

Terry Farrell (Post #4),

In my opinion (and what do I know, really), a Steinway bridge root/trunk (as one example) is made to the "ideal" height at the factory. This vertically laminated member is strong/unyielding in its original height from end to end, with a cap glued atop that is just tall enough to accommodate the deepest union notches. If we reduce the root to accommodate a thicker cap, we weaken it. The cap material is flexible in its linear dimension; the bridge root is not, and there's a reason for that. The root supports the crown along the grain of the soundboard for the life of the instrument. In my rebuilding work, and again what the heck do I know, I never violated the height of the root. I was much happier "wasting" cap material than reducing the root. I know you use a vertically laminated cap, and perhaps this makes up for the loss (but you have introduced a glue joint that never existed at that elevation, and the root structure would be stronger without it, with continuous vertical grain top-to-bottom, methinks), but I have seen scads of rebuilt Steinway and Mason & Hamlin pianos over the last 45 years with significantly reduced roots and chunky quartersawn maple caps, and they distress me.

David G. Hughes, RPT

Baltimore Chapter

In a recent discussion with a colleague I was conveying my method of determining bridge cap thickness in advance of gluing on the new cap material.  This way I can plane the new cap to the proper thickness before gluing it on.  I find that easier, and more accurate, than the traditional method of gluing on an oversize (thickness) cap and then cutting slots in the top and then planing the bridge to the depth of those slots. 

The pictures below are pretty self-explanatory.  I've sent a suggestion to Mazzaglia that they produce something like this out of brass, like their other fine tools.  But you can make one of these out of wood easily enough.  I actually found a metal wedge on line which was exactly these dimension that I use for this purpose, adding the markings myself.  The width of the wedge corresponds to the average spacing between the bridge pins.   

Here's a link to the item I purchased recently after my original wooden wedge that I had made got damaged.  Bueyfolt 1/2" x 3/4" x 4" Flange Wedge, Zinc Plated Metal Flange Wedge Pipe Fitting Welding Tool, Strong Welding Wedge, Rust-Proof, Corrosion Resistant and Strong, Spreading Flanges Triangle Tool - Amazon.com 

Procedurally, you determine the distance bearing at the rear string rest by multiplying the length of the backscale by .0175 for each 1 degree of distance bearing that you want (.0175 is the sine of 1 degree).  I then use the Mazzaglia bearing gauges set on top of the rear string rest and lower the string until it rests on the gauge/string rest and then slide the wedge under the string until it just touches the string.  Read the thickness and that's the bridge cap thickness.  By adding the cap thickness to the bridge root height it will give you how high the top of the cap should be above the SB.  I then write in pencil directly on the SB at that point the target height of the bridge with the cap.  I then plane the cap material to that target plus 1 mm and sand the cap to the final height.  Lay out the bridge pin array and go from there. 

I always pre-stress the board by inserting some wedges under the struts of the piano to "take out the slack" before I take the measurements.  .  

Terry Farrell (Post #4),

In my opinion (and what do I know, really), a Steinway bridge root/trunk (as one example) is made to the "ideal" height at the factory. This vertically laminated member is strong/unyielding in its original height from end to end, with a cap glued atop that is just tall enough to accommodate the deepest union notches. If we reduce the root to accommodate a thicker cap, we weaken it. The cap material is flexible in its linear dimension; the bridge root is not, and there's a reason for that. The root supports the crown along the grain of the soundboard for the life of the instrument. In my rebuilding work, and again what the heck do I know, I never violated the height of the root. I was much happier "wasting" cap material than reducing the root. I know you use a vertically laminated cap, and perhaps this makes up for the loss (but you have introduced a glue joint that never existed at that elevation, and the root structure would be stronger without it, with continuous vertical grain top-to-bottom, methinks), but I have seen scads of rebuilt Steinway and Mason & Hamlin pianos over the last 45 years with significantly reduced roots and chunky quartersawn maple caps, and they distress me.

David G. Hughes, RPT

Baltimore Chapter

In a recent discussion with a colleague I was conveying my method of determining bridge cap thickness in advance of gluing on the new cap material.  This way I can plane the new cap to the proper thickness before gluing it on.  I find that easier, and more accurate, than the traditional method of gluing on an oversize (thickness) cap and then cutting slots in the top and then planing the bridge to the depth of those slots. 

The pictures below are pretty self-explanatory.  I've sent a suggestion to Mazzaglia that they produce something like this out of brass, like their other fine tools.  But you can make one of these out of wood easily enough.  I actually found a metal wedge on line which was exactly these dimension that I use for this purpose, adding the markings myself.  The width of the wedge corresponds to the average spacing between the bridge pins.   

Here's a link to the item I purchased recently after my original wooden wedge that I had made got damaged.  Bueyfolt 1/2" x 3/4" x 4" Flange Wedge, Zinc Plated Metal Flange Wedge Pipe Fitting Welding Tool, Strong Welding Wedge, Rust-Proof, Corrosion Resistant and Strong, Spreading Flanges Triangle Tool - Amazon.com 

Procedurally, you determine the distance bearing at the rear string rest by multiplying the length of the backscale by .0175 for each 1 degree of distance bearing that you want (.0175 is the sine of 1 degree).  I then use the Mazzaglia bearing gauges set on top of the rear string rest and lower the string until it rests on the gauge/string rest and then slide the wedge under the string until it just touches the string.  Read the thickness and that's the bridge cap thickness.  By adding the cap thickness to the bridge root height it will give you how high the top of the cap should be above the SB.  I then write in pencil directly on the SB at that point the target height of the bridge with the cap.  I then plane the cap material to that target plus 1 mm and sand the cap to the final height.  Lay out the bridge pin array and go from there. 

I always pre-stress the board by inserting some wedges under the struts of the piano to "take out the slack" before I take the measurements.  .  

Wow. So many Davids on here. I'm having to scroll back to previous posts to follow it.

Perhaps we could use a last initial? 

"Dave's not here, man"....

Terry Farrell (Post #4),

In my opinion (and what do I know, really), a Steinway bridge root/trunk (as one example) is made to the "ideal" height at the factory. This vertically laminated member is strong/unyielding in its original height from end to end, with a cap glued atop that is just tall enough to accommodate the deepest union notches. If we reduce the root to accommodate a thicker cap, we weaken it. The cap material is flexible in its linear dimension; the bridge root is not, and there's a reason for that. The root supports the crown along the grain of the soundboard for the life of the instrument. In my rebuilding work, and again what the heck do I know, I never violated the height of the root. I was much happier "wasting" cap material than reducing the root. I know you use a vertically laminated cap, and perhaps this makes up for the loss (but you have introduced a glue joint that never existed at that elevation, and the root structure would be stronger without it, with continuous vertical grain top-to-bottom, methinks), but I have seen scads of rebuilt Steinway and Mason & Hamlin pianos over the last 45 years with significantly reduced roots and chunky quartersawn maple caps, and they distress me.

David G. Hughes, RPT

Baltimore Chapter

In a recent discussion with a colleague I was conveying my method of determining bridge cap thickness in advance of gluing on the new cap material.  This way I can plane the new cap to the proper thickness before gluing it on.  I find that easier, and more accurate, than the traditional method of gluing on an oversize (thickness) cap and then cutting slots in the top and then planing the bridge to the depth of those slots. 

The pictures below are pretty self-explanatory.  I've sent a suggestion to Mazzaglia that they produce something like this out of brass, like their other fine tools.  But you can make one of these out of wood easily enough.  I actually found a metal wedge on line which was exactly these dimension that I use for this purpose, adding the markings myself.  The width of the wedge corresponds to the average spacing between the bridge pins.   

Here's a link to the item I purchased recently after my original wooden wedge that I had made got damaged.  Bueyfolt 1/2" x 3/4" x 4" Flange Wedge, Zinc Plated Metal Flange Wedge Pipe Fitting Welding Tool, Strong Welding Wedge, Rust-Proof, Corrosion Resistant and Strong, Spreading Flanges Triangle Tool - Amazon.com 

Procedurally, you determine the distance bearing at the rear string rest by multiplying the length of the backscale by .0175 for each 1 degree of distance bearing that you want (.0175 is the sine of 1 degree).  I then use the Mazzaglia bearing gauges set on top of the rear string rest and lower the string until it rests on the gauge/string rest and then slide the wedge under the string until it just touches the string.  Read the thickness and that's the bridge cap thickness.  By adding the cap thickness to the bridge root height it will give you how high the top of the cap should be above the SB.  I then write in pencil directly on the SB at that point the target height of the bridge with the cap.  I then plane the cap material to that target plus 1 mm and sand the cap to the final height.  Lay out the bridge pin array and go from there. 

I always pre-stress the board by inserting some wedges under the struts of the piano to "take out the slack" before I take the measurements.  .  

Wow. So many Davids on here. I'm having to scroll back to previous posts to follow it.

Perhaps we could use a last initial? 

"Dave's not here, man"....

Terry Farrell (Post #4),

In my opinion (and what do I know, really), a Steinway bridge root/trunk (as one example) is made to the "ideal" height at the factory. This vertically laminated member is strong/unyielding in its original height from end to end, with a cap glued atop that is just tall enough to accommodate the deepest union notches. If we reduce the root to accommodate a thicker cap, we weaken it. The cap material is flexible in its linear dimension; the bridge root is not, and there's a reason for that. The root supports the crown along the grain of the soundboard for the life of the instrument. In my rebuilding work, and again what the heck do I know, I never violated the height of the root. I was much happier "wasting" cap material than reducing the root. I know you use a vertically laminated cap, and perhaps this makes up for the loss (but you have introduced a glue joint that never existed at that elevation, and the root structure would be stronger without it, with continuous vertical grain top-to-bottom, methinks), but I have seen scads of rebuilt Steinway and Mason & Hamlin pianos over the last 45 years with significantly reduced roots and chunky quartersawn maple caps, and they distress me.

David G. Hughes, RPT

Baltimore Chapter

In a recent discussion with a colleague I was conveying my method of determining bridge cap thickness in advance of gluing on the new cap material.  This way I can plane the new cap to the proper thickness before gluing it on.  I find that easier, and more accurate, than the traditional method of gluing on an oversize (thickness) cap and then cutting slots in the top and then planing the bridge to the depth of those slots. 

The pictures below are pretty self-explanatory.  I've sent a suggestion to Mazzaglia that they produce something like this out of brass, like their other fine tools.  But you can make one of these out of wood easily enough.  I actually found a metal wedge on line which was exactly these dimension that I use for this purpose, adding the markings myself.  The width of the wedge corresponds to the average spacing between the bridge pins.   

Here's a link to the item I purchased recently after my original wooden wedge that I had made got damaged.  Bueyfolt 1/2" x 3/4" x 4" Flange Wedge, Zinc Plated Metal Flange Wedge Pipe Fitting Welding Tool, Strong Welding Wedge, Rust-Proof, Corrosion Resistant and Strong, Spreading Flanges Triangle Tool - Amazon.com 

Procedurally, you determine the distance bearing at the rear string rest by multiplying the length of the backscale by .0175 for each 1 degree of distance bearing that you want (.0175 is the sine of 1 degree).  I then use the Mazzaglia bearing gauges set on top of the rear string rest and lower the string until it rests on the gauge/string rest and then slide the wedge under the string until it just touches the string.  Read the thickness and that's the bridge cap thickness.  By adding the cap thickness to the bridge root height it will give you how high the top of the cap should be above the SB.  I then write in pencil directly on the SB at that point the target height of the bridge with the cap.  I then plane the cap material to that target plus 1 mm and sand the cap to the final height.  Lay out the bridge pin array and go from there. 

I always pre-stress the board by inserting some wedges under the struts of the piano to "take out the slack" before I take the measurements.  .  

Dave Conte (Post #31),

If everyone who contributes to any discussion anywhere on PTG-L would include the Post number they are responding to (as one of us has done for years, ahem!) there would be no confusion as to who is replying to whom.

David G. Hughes, RPT

Baltimore Chapter

Wow. So many Davids on here. I'm having to scroll back to previous posts to follow it.

Perhaps we could use a last initial? 

"Dave's not here, man"....

Terry Farrell (Post #4),

In my opinion (and what do I know, really), a Steinway bridge root/trunk (as one example) is made to the "ideal" height at the factory. This vertically laminated member is strong/unyielding in its original height from end to end, with a cap glued atop that is just tall enough to accommodate the deepest union notches. If we reduce the root to accommodate a thicker cap, we weaken it. The cap material is flexible in its linear dimension; the bridge root is not, and there's a reason for that. The root supports the crown along the grain of the soundboard for the life of the instrument. In my rebuilding work, and again what the heck do I know, I never violated the height of the root. I was much happier "wasting" cap material than reducing the root. I know you use a vertically laminated cap, and perhaps this makes up for the loss (but you have introduced a glue joint that never existed at that elevation, and the root structure would be stronger without it, with continuous vertical grain top-to-bottom, methinks), but I have seen scads of rebuilt Steinway and Mason & Hamlin pianos over the last 45 years with significantly reduced roots and chunky quartersawn maple caps, and they distress me.

David G. Hughes, RPT

Baltimore Chapter

In a recent discussion with a colleague I was conveying my method of determining bridge cap thickness in advance of gluing on the new cap material.  This way I can plane the new cap to the proper thickness before gluing it on.  I find that easier, and more accurate, than the traditional method of gluing on an oversize (thickness) cap and then cutting slots in the top and then planing the bridge to the depth of those slots. 

The pictures below are pretty self-explanatory.  I've sent a suggestion to Mazzaglia that they produce something like this out of brass, like their other fine tools.  But you can make one of these out of wood easily enough.  I actually found a metal wedge on line which was exactly these dimension that I use for this purpose, adding the markings myself.  The width of the wedge corresponds to the average spacing between the bridge pins.   

Here's a link to the item I purchased recently after my original wooden wedge that I had made got damaged.  Bueyfolt 1/2" x 3/4" x 4" Flange Wedge, Zinc Plated Metal Flange Wedge Pipe Fitting Welding Tool, Strong Welding Wedge, Rust-Proof, Corrosion Resistant and Strong, Spreading Flanges Triangle Tool - Amazon.com 

Procedurally, you determine the distance bearing at the rear string rest by multiplying the length of the backscale by .0175 for each 1 degree of distance bearing that you want (.0175 is the sine of 1 degree).  I then use the Mazzaglia bearing gauges set on top of the rear string rest and lower the string until it rests on the gauge/string rest and then slide the wedge under the string until it just touches the string.  Read the thickness and that's the bridge cap thickness.  By adding the cap thickness to the bridge root height it will give you how high the top of the cap should be above the SB.  I then write in pencil directly on the SB at that point the target height of the bridge with the cap.  I then plane the cap material to that target plus 1 mm and sand the cap to the final height.  Lay out the bridge pin array and go from there. 

I always pre-stress the board by inserting some wedges under the struts of the piano to "take out the slack" before I take the measurements.  .  

Dave Conte (Post #31),

If everyone who contributes to any discussion anywhere on PTG-L would include the Post number they are responding to (as one of us has done for years, ahem!) there would be no confusion as to who is replying to whom.

David G. Hughes, RPT

Baltimore Chapter

Wow. So many Davids on here. I'm having to scroll back to previous posts to follow it.

Perhaps we could use a last initial? 

"Dave's not here, man"....

Terry Farrell (Post #4),

In my opinion (and what do I know, really), a Steinway bridge root/trunk (as one example) is made to the "ideal" height at the factory. This vertically laminated member is strong/unyielding in its original height from end to end, with a cap glued atop that is just tall enough to accommodate the deepest union notches. If we reduce the root to accommodate a thicker cap, we weaken it. The cap material is flexible in its linear dimension; the bridge root is not, and there's a reason for that. The root supports the crown along the grain of the soundboard for the life of the instrument. In my rebuilding work, and again what the heck do I know, I never violated the height of the root. I was much happier "wasting" cap material than reducing the root. I know you use a vertically laminated cap, and perhaps this makes up for the loss (but you have introduced a glue joint that never existed at that elevation, and the root structure would be stronger without it, with continuous vertical grain top-to-bottom, methinks), but I have seen scads of rebuilt Steinway and Mason & Hamlin pianos over the last 45 years with significantly reduced roots and chunky quartersawn maple caps, and they distress me.

David G. Hughes, RPT

Baltimore Chapter

In a recent discussion with a colleague I was conveying my method of determining bridge cap thickness in advance of gluing on the new cap material.  This way I can plane the new cap to the proper thickness before gluing it on.  I find that easier, and more accurate, than the traditional method of gluing on an oversize (thickness) cap and then cutting slots in the top and then planing the bridge to the depth of those slots. 

The pictures below are pretty self-explanatory.  I've sent a suggestion to Mazzaglia that they produce something like this out of brass, like their other fine tools.  But you can make one of these out of wood easily enough.  I actually found a metal wedge on line which was exactly these dimension that I use for this purpose, adding the markings myself.  The width of the wedge corresponds to the average spacing between the bridge pins.   

Here's a link to the item I purchased recently after my original wooden wedge that I had made got damaged.  Bueyfolt 1/2" x 3/4" x 4" Flange Wedge, Zinc Plated Metal Flange Wedge Pipe Fitting Welding Tool, Strong Welding Wedge, Rust-Proof, Corrosion Resistant and Strong, Spreading Flanges Triangle Tool - Amazon.com 

Procedurally, you determine the distance bearing at the rear string rest by multiplying the length of the backscale by .0175 for each 1 degree of distance bearing that you want (.0175 is the sine of 1 degree).  I then use the Mazzaglia bearing gauges set on top of the rear string rest and lower the string until it rests on the gauge/string rest and then slide the wedge under the string until it just touches the string.  Read the thickness and that's the bridge cap thickness.  By adding the cap thickness to the bridge root height it will give you how high the top of the cap should be above the SB.  I then write in pencil directly on the SB at that point the target height of the bridge with the cap.  I then plane the cap material to that target plus 1 mm and sand the cap to the final height.  Lay out the bridge pin array and go from there. 

I always pre-stress the board by inserting some wedges under the struts of the piano to "take out the slack" before I take the measurements.  .  

Folks, interesting discussion of details. Any chance of getting to the higher level of my previous questions:

(a) In homes and stores I find some rebuilt grand pianos with areas of tonal deficiencies, particularly in the treble. If my observations are correct, what are the (average) odds for a successful rebuild? 

(b) In Nick Gravagne's articles that David L referred to, in (PTJ April 1988), Nick refers to an acceptable downbearing leeway of plus or minus 1 ½ degrees in a rebuild. But wouldn't this take the downbearing close to 8 pounds or close to 0 pounds (PTJ March 1988 table), both being extremes that could be unacceptable? 

(c) With the non-linear physical downbearing that Nick refers to (PTJ May 1988), and his example of a resultant 1/16" shift (treble from tenor pressure), how does a rebuilder compensate for that? Such as: do you pre-adjust the bridge cap for (unloaded) near-zero treble downbearing knowing that in stringing from note 1 to 88 that the desired 4 pounds of downbearing will develop? Regards, Norman. 

Dave Conte (Post #31),

If everyone who contributes to any discussion anywhere on PTG-L would include the Post number they are responding to (as one of us has done for years, ahem!) there would be no confusion as to who is replying to whom.

David G. Hughes, RPT

Baltimore Chapter