Pianotech

I have a Baldwin Hamilton 243 (1964) project piano that came free to me, condemned from a local church because the bass bridge had slipped.  Upon inspection, the bridge also has side bearing cracks.  Instead of considering an epoxy/CA solution, I've decided to duplicate the bridge for my own experience.  I've included pictures of the bass bridge and any suggestions on doing this properly would be appreciated.  

Current plan: 

1. Determine original bridge pin angle
2. Pull bridge pins
3. Use clear acetate film and a punch to create a bridge pin pattern
4. Cut a hard maple blank duplicate of original (Please help me with grain orientation here)
5. Mark and drill (drill press) new bridge pin holes in maple blank using pattern and measured angle
6. Apply dag ('cause it's pretty)
6. Notch the bridge (Any guidance on the best method in this case would be appreciated!)
7. Drive new pins
8. Attach bridge to riser

Side note regarding my terms: This is only my second slipped bass bridge repair.  The first was on an old Brinkerhoff upright.  Its bass bridge arrangement (counting from the soundboard) was: riser-apron-bridge.  This Hamilton appears to have an apron-riser-bridge arrangement. 

The original glue only approach was insufficient to hold the bridge to the riser and I would like to do more but have no idea what would be best (glue + flat head screws through the center of the bridge?).  Suggestions appreciated. 

If the riser and apron seem tight to each other and the soundboard, should I leave it at that?  Remember, this is a project piano and I realize that I'm going above and beyond a typical economically practical solution.

Thanks!


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Michael Staples
PTG Associate member
Lexington, KY
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Michael

This is a good piano to start on for a variety of reasons.  First the bridge is straight which allows for an easier duplication.  Second it is in a vertical so you can actually use a piece of scrap pinblock material which will give you additional strength and not be cosmetically offensive as it is inside "the box."  You will need to duplicate the thickness of the original bridge as this will affect the downbearing.  If the apron is still solidly attached you will have to get a little creative when gluing the new bridge to the apron.  Often the apron has some screws installed from the back (soundboard) side through the thin material into the thicker bridge body.  If the apron is loose at all this is a preferred method of repair as you will both glue it in place as well as use mechanical fasteners for additional holding and locating purposes.  If the apron is both solid and solidly attached it is possible to drill countersunk screwholes through the bridge between the two rows of bridge pins.  If you do this properly the screws will be below the surface of the bridge and will not interfere with the strings in any way.  Drywall type screws often work well in this application.

When it comes to marking the bridge pin locations I will often tilt the piano on its back using a tilter and dry fit the new bridge blank into place.   I will then use a piece of fishing line stretched from the hitch pin to the upper termination pin to mark the location of the strings.  Place a mark on one side of the string along the top row of pins and place a mark on the other side of the string along the top row of pins.  This opposite side marking will give you adequate side bearing.  Once you have all the marks made you can drill the bridge pin holes either by hand if you are steady with a hand drill or remove the bridge blank and drill them at the drill press.  Ususally they are drilled at a compound angle.  If I am drilling them by hand it is handy to cut a small piece of scrap at an angle that I can use as a visual alignment tool when drilling.  You can set up the drill press for compound angles with a little creative swiveling of either the base in the case of a fixed head drill press or swivelling the head on a radial drill press.  The compound angle can be achieved by clamping an angled top to the drill press.  The easiest way to make this is to take a couple of pieces of plywood and hinge them togther and open the "book" up to the appropriate angle.  Slip a few scraps of wood between the two pieces to hold the "book"open and clamp it to the drill press table.

After the bridge pin holes are drilled the use of a good sharp hand plane can create the bevel back to the pins to form the continuous notch.  If you apply the dag you mentioned because it "looks purdy" the visual line helps you know when you have planed back far enough.  Install the pins and glue, screw and tattoo the bridge back into the piano and you are good to go.

Good luck
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Norman Cantrell
Piano Clinic
Lawton OK
580-355-5003
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Original Message:
Sent: 10-10-2011 17:50
From: Michael Staples
Subject: Beginner bass bridge reproduction


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yes, the beveled edge is straight and so the chisel idea that I suggested is a bad idea in this application.

sorry  .......   I was thinking of individual notching.  Silly me.
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Larry Fisher
Owner, Chief Grunt, Head Hosehead
Vancouver WA
360-256-2999
-------------------------------------------






Original Message:
Sent: 10-11-2011 08:47
From: Norman Cantrell
Subject: Beginner bass bridge reproduction

Michael

This is a good piano to start on for a variety of reasons.  First the bridge is straight which allows for an easier duplication.  Second it is in a vertical so you can actually use a piece of scrap pinblock material which will give you additional strength and not be cosmetically offensive as it is inside "the box."  You will need to duplicate the thickness of the original bridge as this will affect the downbearing.  If the apron is still solidly attached you will have to get a little creative when gluing the new bridge to the apron.  Often the apron has some screws installed from the back (soundboard) side through the thin material into the thicker bridge body.  If the apron is loose at all this is a preferred method of repair as you will both glue it in place as well as use mechanical fasteners for additional holding and locating purposes.  If the apron is both solid and solidly attached it is possible to drill countersunk screwholes through the bridge between the two rows of bridge pins.  If you do this properly the screws will be below the surface of the bridge and will not interfere with the strings in any way.  Drywall type screws often work well in this application.

When it comes to marking the bridge pin locations I will often tilt the piano on its back using a tilter and dry fit the new bridge blank into place.   I will then use a piece of fishing line stretched from the hitch pin to the upper termination pin to mark the location of the strings.  Place a mark on one side of the string along the top row of pins and place a mark on the other side of the string along the top row of pins.  This opposite side marking will give you adequate side bearing.  Once you have all the marks made you can drill the bridge pin holes either by hand if you are steady with a hand drill or remove the bridge blank and drill them at the drill press.  Ususally they are drilled at a compound angle.  If I am drilling them by hand it is handy to cut a small piece of scrap at an angle that I can use as a visual alignment tool when drilling.  You can set up the drill press for compound angles with a little creative swiveling of either the base in the case of a fixed head drill press or swivelling the head on a radial drill press.  The compound angle can be achieved by clamping an angled top to the drill press.  The easiest way to make this is to take a couple of pieces of plywood and hinge them togther and open the "book" up to the appropriate angle.  Slip a few scraps of wood between the two pieces to hold the "book"open and clamp it to the drill press table.

After the bridge pin holes are drilled the use of a good sharp hand plane can create the bevel back to the pins to form the continuous notch.  If you apply the dag you mentioned because it "looks purdy" the visual line helps you know when you have planed back far enough.  Install the pins and glue, screw and tattoo the bridge back into the piano and you are good to go.

Good luck
-------------------------------------------
Norman Cantrell
Piano Clinic
Lawton OK
580-355-5003
-------------------------------------------






Original Message:
Sent: 10-10-2011 17:50
From: Michael Staples
Subject: Beginner bass bridge reproduction


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I like Norman Cantrell's method of locating the bridge pin holes, better than a pattern. A pattern may duplicate the problem that caused the original splitting or other problem. Norman's wording was a little confusing (including a typo I believe, where he seems to have substituted top for bottom in the second phrase of the third sentence quoted below). My own method is to start by scribing a line on the bridge (this type of bridge where there is no individual notching for unisons, just a beveled edge), on each side of the bridge, duplicating the distance of the original bevel. I then stretch a string from hitch pin to the nut pin, and mark precisely under the middle of the string, on each of the lines I made.

Now I decide how much side bearing I want, which depends on the thickness of the bridge pins. If you drill in the middle of each mark that has been made, the offset will start as being the thickness of a pin (if it was drilled 90 degrees, rather than angled), and will increase due to the angle. So for large pins like on a bass bridge I will punch and drill to the side of each of my marks to make the offset less (I think this is what Norman was saying as well). (This is usually true also of treble pins, but not as much). You need a good positive offset, but not an excessive one. Look at other pianos to get a good idea of the right amount of offset - I've never measured it as an angle, but I have a good eyeball estimate. 

Another reason to use this method rather than following a pattern is that it definitely centers the pins on the string line, so there won't be a sideways draft - again, something wrong you might be duplicating if you simply use a pattern. It isn't a bad idea, though, to take a pattern and see how it matches up with your decisions as a check.

Cantrell: "When it comes to marking the bridge pin locations I will often tilt the piano on its back using a tilter and dry fit the new bridge blank into place.   I will then use a piece of fishing line stretched from the hitch pin to the upper termination pin to mark the location of the strings.  Place a mark on one side of the string along the top row of pins and place a mark on the other side of the string along the top row of pins.  This opposite side marking will give you adequate side bearing.  Once you have all the marks made you can drill the bridge pin holes either by hand if you are steady with a hand drill or remove the bridge blank and drill them at the drill press."

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Fred Sturm
University of New Mexico
fssturm@unm.edu
"The true sign of intelligence is not knowledge, but imagination." - Einstein
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Fred

Thanks for catching my wording slip.  I guess I thought I was more awake than I was.  You are right that this method corrects factory mistakes.  I have had more than one bridge that was damaged due to excessive side bearing on the pins as the line between the hitch pin and the upper string termination (pin, agraffe, etc) was grossly distorted.  I even remember adding a hitch pin to the plate of a player piano when repairing such bridge damage and making a new cap.  Also the idea of scribing a line on the bridge to mark the offset from the edge is a good practice. 

-------------------------------------------
Norman Cantrell
Piano Clinic
Lawton OK
580-355-5003
-------------------------------------------

Thanks to all who replied! I'm proceeding with the bridge replacement and your suggestions will certainly help me begin doing good work sooner that I could have on my own. Michael Staples On Wed, Oct 12, 2011 at 9:38 AM, Norman Cantrell wrote: > > > Fred > > Thanks for catching my wording slip. I guess I thought I was more awake > than I was. You are right that this method corrects factory mistakes. I > have had more than one bridge that was damaged due to excessive side bearing > on the pins as the line between the hitch pin and the upper string > termination (pin, agraffe, etc) was grossly distorted. I even remember > adding a hitch pin to the plate of a player piano when repairing such bridge > damage and making a new cap. Also the idea of scribing a line on the bridge > to mark the offset from the edge is a good practice. > > ------------------------------------------- > Norman Cantrell > Piano Clinic > Lawton OK > 580-355-5003 > ------------------------------------------- > > > > > > > > > > >

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Michael Staples
PTG Associate member
Lexington, KY
-------------------------------------------

Remove the bridge body and measure the distance from the string to the apron at 3 or 4 positions along the section. Don't use string, use thread. Place the loop on a tuning pin, draw taut and press the thread onto a nickel placed on the plate at the hitch pin, this will give you the needed down bearing.

Your replacement probably will be tapered. Use pin block stock and avoid making a cap. To determine pin placement, draw the thread for each wire. Bichords can be marked directly under the thread and singles marks
on the sides, this will account for the larger pins on the singles. As for the direction and angle of the pins, copy
the alignment from the treble bridge.

If the hitch pins a loose enough to pull out, replace them with tension pins to make vertical hitch pins and make your bridge body a little taller. The advantage of this is increased back scale length and there's no need for precise measurements on bridge height. This is my preferred method.
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Regards,

Jon Page

Thanks Jon!

What gives me pause is that with the original bridge in place, it seems so skewed to the string plane.

MS
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Michael Staples
PTG Associate member
Lexington, KY
-------------------------------------------






Original Message:
Sent: 11-12-2011 16:44
From: Jon Page
Subject: Beginner bass bridge reproduction

Remove the bridge body and measure the distance from the string to the apron at 3 or 4 positions along the section. Don't use string, use thread. Place the loop on a tuning pin, draw taut and press the thread onto a nickel placed on the plate at the hitch pin, this will give you the needed down bearing.

Your replacement probably will be tapered. Use pin block stock and avoid making a cap. To determine pin placement, draw the thread for each wire. Bichords can be marked directly under the thread and singles marks
on the sides, this will account for the larger pins on the singles. As for the direction and angle of the pins, copy
the alignment from the treble bridge.

If the hitch pins a loose enough to pull out, replace them with tension pins to make vertical hitch pins and make your bridge body a little taller. The advantage of this is increased back scale length and there's no need for precise measurements on bridge height. This is my preferred method.
-------------------------------------------
Regards,

Jon Page

Hey Jon, are you saying that you use pinblock material to make bridges??  I've never looked at the stuff up close with bridge making in mind.  Basic physics of sound dictate that vertical grain or growth rings that align with the travel of sound  ........  the string to the soundboard or apron in this case  ............  are the best for the transmission of sound.

I can understand that the density of pinblock material is good enough to handle this job on most vertical pianos.

I guess I never would have considered this as an option.


-------------------------------------------
Larry Fisher
Owner, Chief Grunt, Head Hosehead
Vancouver WA
360-256-2999
-------------------------------------------






Original Message:
Sent: 11-12-2011 16:44
From: Jon Page
Subject: Beginner bass bridge reproduction

Remove the bridge body and measure the distance from the string to the apron at 3 or 4 positions along the section. Don't use string, use thread. Place the loop on a tuning pin, draw taut and press the thread onto a nickel placed on the plate at the hitch pin, this will give you the needed down bearing.

Your replacement probably will be tapered. Use pin block stock and avoid making a cap. To determine pin placement, draw the thread for each wire. Bichords can be marked directly under the thread and singles marks
on the sides, this will account for the larger pins on the singles. As for the direction and angle of the pins, copy
the alignment from the treble bridge.

If the hitch pins a loose enough to pull out, replace them with tension pins to make vertical hitch pins and make your bridge body a little taller. The advantage of this is increased back scale length and there's no need for precise measurements on bridge height. This is my preferred method.
-------------------------------------------
Regards,

Jon Page

I've been to a class on this taught by a very talented man from Texas  ......  I'm really sorry I don't remember names worth beans.

Sound travels with the grain easier than through it.  Orientate your grain to connect between the apron and the bridge as vertical as possible.  Look closely at other bridges to get the finer details of this.

In the class, we were told that the piano builders in the factory used a hand held rotary tool to drill the pin holes and simply estimated the angle.  Drill the holes first then chisel away the wood placing your chisel in the middle of the holes.  He liked to use old dull files, shortened to about 6 inches, sharpened to a razor's edge and wrapped with tape and small blocks of wood to facilitate a handle that he'd hit with the heel of his hand.  We all tried it and were amazed at how easy you could generate a scooped/beveled approach in the wood to the pins.  One hit and the job was done.  Mind you this required a VERY sharp edge on the "chisel".  He mentioned spending an entire day sharpening his tools before attempting this part of the job and used a rotary whet stone.  Traveling knife sharpeners have these. Call a restaurant to get contact information.

As for attaching the finished product to the apron/riser I've heard of hidden screws being used.  I prefer to remove the riser/apron from the soundboard and attach it from the back side of the apron.  To do this you have to remove it from the soundboard.  I've drilled holes through the backpost to gain access to those screws.  In the past I used a chisel to remove the riser from the soundboard but now a days there's this fantastic tool called the Wein Multitool or cheaper facsimile.  It would do a most beautiful job of breaking the glue joint for you.  Any damage to the riser can be eliminated by making a new one.

I admire your determination to facilitate your knowledge on this.  Good luck and don't give up.

Lar



-------------------------------------------
Larry Fisher
Owner, Chief Grunt, Head Hosehead
Vancouver WA
360-256-2999
-------------------------------------------






Original Message:
Sent: 10-10-2011 17:50
From: Michael Staples
Subject: Beginner bass bridge reproduction


I have a Baldwin Hamilton 243 (1964) project piano that came free to me, condemned from a local church because the bass bridge had slipped.  Upon inspection, the bridge also has side bearing cracks.  Instead of considering an epoxy/CA solution, I've decided to duplicate the bridge for my own experience.  I've included pictures of the bass bridge and any suggestions on doing this properly would be appreciated.  

Current plan: 

1. Determine original bridge pin angle
2. Pull bridge pins
3. Use clear acetate film and a punch to create a bridge pin pattern
4. Cut a hard maple blank duplicate of original (Please help me with grain orientation here)
5. Mark and drill (drill press) new bridge pin holes in maple blank using pattern and measured angle
6. Apply dag ('cause it's pretty)
6. Notch the bridge (Any guidance on the best method in this case would be appreciated!)
7. Drive new pins
8. Attach bridge to riser

Side note regarding my terms: This is only my second slipped bass bridge repair.  The first was on an old Brinkerhoff upright.  Its bass bridge arrangement (counting from the soundboard) was: riser-apron-bridge.  This Hamilton appears to have an apron-riser-bridge arrangement. 

The original glue only approach was insufficient to hold the bridge to the riser and I would like to do more but have no idea what would be best (glue + flat head screws through the center of the bridge?).  Suggestions appreciated. 

If the riser and apron seem tight to each other and the soundboard, should I leave it at that?  Remember, this is a project piano and I realize that I'm going above and beyond a typical economically practical solution.

Thanks!


-------------------------------------------
Michael Staples
PTG Associate member
Lexington, KY
-------------------------------------------