Pianotech

I've read about people who simulate down pressure of strings on the soundboard prior to getting downbearing measurements for new bridge cap on either a new soundboard or even an old one if original measurements are slightly adjusted or if many shims were added to an old board. I haven't found any more information about specific ways this down pressure can be d. Are weights added to the board? Can you use the plate struts with wedges/jacks between the soundboard and plate strut? Any description, articles, or pictures you can share would be very much appreciated. Thank you!

I've read about people who simulate down pressure of strings on the soundboard prior to getting downbearing measurements for new bridge cap on either a new soundboard or even an old one if original measurements are slightly adjusted or if many shims were added to an old board. I haven't found any more information about specific ways this down pressure can be d. Are weights added to the board? Can you use the plate struts with wedges/jacks between the soundboard and plate strut? Any description, articles, or pictures you can share would be very much appreciated. Thank you!

Tim,

I had a 4"x4" beam that clamped to the top of the rim, spanning the soundboard from side to side. In the middle of that beam was a screw press: as you cranked the handle, a foot on the end of the threaded shaft raised or lowered. This foot could hover anywhere above the soundboard desired, but I placed it at about note 40 on the bridge. The handle was cranked downward, thus compressing (flattening) the soundboard to the desired/anticipated amount, simulating string downbearing pressure. In my opinion you only need to force the board down at one location - the middle of the board. All the other surface area and structure will follow accordingly.

David G. Hughes, RPT 

I've read about people who simulate down pressure of strings on the soundboard prior to getting downbearing measurements for new bridge cap on either a new soundboard or even an old one if original measurements are slightly adjusted or if many shims were added to an old board. I haven't found any more information about specific ways this down pressure can be d. Are weights added to the board? Can you use the plate struts with wedges/jacks between the soundboard and plate strut? Any description, articles, or pictures you can share would be very much appreciated. Thank you!

Dave,

This is great, thank you!

Cecil,

I like the idea of the WNG plate screws, although it seems many pianos (ok, Steinway) don't have enough dowel clearance without grinding the plate.

 Many thanks for the advice!

Tim,

I had a 4"x4" beam that clamped to the top of the rim, spanning the soundboard from side to side. In the middle of that beam was a screw press: as you cranked the handle, a foot on the end of the threaded shaft raised or lowered. This foot could hover anywhere above the soundboard desired, but I placed it at about note 40 on the bridge. The handle was cranked downward, thus compressing (flattening) the soundboard to the desired/anticipated amount, simulating string downbearing pressure. In my opinion you only need to force the board down at one location - the middle of the board. All the other surface area and structure will follow accordingly.

David G. Hughes, RPT 

I've read about people who simulate down pressure of strings on the soundboard prior to getting downbearing measurements for new bridge cap on either a new soundboard or even an old one if original measurements are slightly adjusted or if many shims were added to an old board. I haven't found any more information about specific ways this down pressure can be d. Are weights added to the board? Can you use the plate struts with wedges/jacks between the soundboard and plate strut? Any description, articles, or pictures you can share would be very much appreciated. Thank you!

Tim,

I would agree with Cecil. I never used the WN&G plate bolts in Steinway pianos: insufficient headroom. These products are simply delicious in almost every other brand of grand piano, though. A godsend.

David G. Hughes, RPT

Dave,

This is great, thank you!

Cecil,

I like the idea of the WNG plate screws, although it seems many pianos (ok, Steinway) don't have enough dowel clearance without grinding the plate.

 Many thanks for the advice!

Tim,

I had a 4"x4" beam that clamped to the top of the rim, spanning the soundboard from side to side. In the middle of that beam was a screw press: as you cranked the handle, a foot on the end of the threaded shaft raised or lowered. This foot could hover anywhere above the soundboard desired, but I placed it at about note 40 on the bridge. The handle was cranked downward, thus compressing (flattening) the soundboard to the desired/anticipated amount, simulating string downbearing pressure. In my opinion you only need to force the board down at one location - the middle of the board. All the other surface area and structure will follow accordingly.

David G. Hughes, RPT 

I've read about people who simulate down pressure of strings on the soundboard prior to getting downbearing measurements for new bridge cap on either a new soundboard or even an old one if original measurements are slightly adjusted or if many shims were added to an old board. I haven't found any more information about specific ways this down pressure can be d. Are weights added to the board? Can you use the plate struts with wedges/jacks between the soundboard and plate strut? Any description, articles, or pictures you can share would be very much appreciated. Thank you!

Tim,

I would agree with Cecil. I never used the WN&G plate bolts in Steinway pianos: insufficient headroom. These products are simply delicious in almost every other brand of grand piano, though. A godsend.

David G. Hughes, RPT

Dave,

This is great, thank you!

Cecil,

I like the idea of the WNG plate screws, although it seems many pianos (ok, Steinway) don't have enough dowel clearance without grinding the plate.

 Many thanks for the advice!

Tim,

I had a 4"x4" beam that clamped to the top of the rim, spanning the soundboard from side to side. In the middle of that beam was a screw press: as you cranked the handle, a foot on the end of the threaded shaft raised or lowered. This foot could hover anywhere above the soundboard desired, but I placed it at about note 40 on the bridge. The handle was cranked downward, thus compressing (flattening) the soundboard to the desired/anticipated amount, simulating string downbearing pressure. In my opinion you only need to force the board down at one location - the middle of the board. All the other surface area and structure will follow accordingly.

David G. Hughes, RPT 

I've read about people who simulate down pressure of strings on the soundboard prior to getting downbearing measurements for new bridge cap on either a new soundboard or even an old one if original measurements are slightly adjusted or if many shims were added to an old board. I haven't found any more information about specific ways this down pressure can be d. Are weights added to the board? Can you use the plate struts with wedges/jacks between the soundboard and plate strut? Any description, articles, or pictures you can share would be very much appreciated. Thank you!

I've read about people who simulate down pressure of strings on the soundboard prior to getting downbearing measurements for new bridge cap on either a new soundboard or even an old one if original measurements are slightly adjusted or if many shims were added to an old board. I haven't found any more information about specific ways this down pressure can be d. Are weights added to the board? Can you use the plate struts with wedges/jacks between the soundboard and plate strut? Any description, articles, or pictures you can share would be very much appreciated. Thank you!

THE PIANO ITS ACOUSTICS BY W. V. McFERRIN 1972↑

Might be a little off topic，I also have similar problem

 actually I still don't understand what level of down bearing is best.

Soundboard tension, down bearing, string tension, what's the most rational relationship between

These three should be considered comprehensively, right?These three should be considered comprehensively, right?

All these calculations are still based on the state of the soundboard. The state of the soundboard is the basis of these calculations. Can I understand it this way?

Therefore, according to the state of the soundboard, calculate the tension of the soundboard, adjust the relative height of the piano cast iron plate, and fine-tune the relative height of the cast iron plate (the height of Duplex-Skalen) according to the down bearing.

Maybe there is no need to go to so much trouble and just adjust the relative height of the cast iron plate and Duplex-Skalen according to the down bearing, right

I've read about people who simulate down pressure of strings on the soundboard prior to getting downbearing measurements for new bridge cap on either a new soundboard or even an old one if original measurements are slightly adjusted or if many shims were added to an old board. I haven't found any more information about specific ways this down pressure can be d. Are weights added to the board? Can you use the plate struts with wedges/jacks between the soundboard and plate strut? Any description, articles, or pictures you can share would be very much appreciated. Thank you!

THE PIANO ITS ACOUSTICS BY W. V. McFERRIN 1972↑

Might be a little off topic，I also have similar problem

 actually I still don't understand what level of down bearing is best.

Soundboard tension, down bearing, string tension, what's the most rational relationship between

These three should be considered comprehensively, right?These three should be considered comprehensively, right?

All these calculations are still based on the state of the soundboard. The state of the soundboard is the basis of these calculations. Can I understand it this way?

Therefore, according to the state of the soundboard, calculate the tension of the soundboard, adjust the relative height of the piano cast iron plate, and fine-tune the relative height of the cast iron plate (the height of Duplex-Skalen) according to the down bearing.

Maybe there is no need to go to so much trouble and just adjust the relative height of the cast iron plate and Duplex-Skalen according to the down bearing, right

I've read about people who simulate down pressure of strings on the soundboard prior to getting downbearing measurements for new bridge cap on either a new soundboard or even an old one if original measurements are slightly adjusted or if many shims were added to an old board. I haven't found any more information about specific ways this down pressure can be d. Are weights added to the board? Can you use the plate struts with wedges/jacks between the soundboard and plate strut? Any description, articles, or pictures you can share would be very much appreciated. Thank you!

Z Huang wrote: I still don't understand what level of down bearing is best. Soundboard tension, down bearing, string tension, what's the most rational relationship between. These three should be considered comprehensively, right? These three should be considered comprehensively, right? All these calculations are still based on the state of the soundboard. The state of the soundboard is the basis of these calculations. Can I understand it this way? Therefore, according to the state of the soundboard, calculate the tension of the soundboard, adjust the relative height of the piano cast iron plate, and fine-tune the relative height of the cast iron plate (the height of Duplex-Skalen) according to the down bearing.

Ask 10 different techs and you'll probably get 10 different answers.  But the short answer is yes, all these things should be considered comprehensively.  Typically, when a soundboard is being designed, the total downbearing is taken into consideration when designing the load bearing properties (i.e. the rib scale) to support the load.  The basic idea is that it must support the load but not be too stiff or too massive or the energy from the strings won't be able to move it adequately to generate ample enough pressure waves in the air and the piano will lack power, even if it exhibits good sustain.

Typically, the boards have been designed to compress about 50-60% under load.  That compression stiffens the board effectively without building in additional mass in, say, the ribs or the panel.  Each soundboard designer will develop their own standard and that % can vary with a number of things including string tensions, downbearing settings, amount of crown, personal impedance preferences etc.  Each one should be considered before making a final call and all these numbers come about with some testing, though there are general guidelines.  

On older soundboards the typical approach is to compress it as much as you can to try and achieve the requisite stiffness, as close as you had before, that has been lost due to age and accompanying loss of crown.  The limit has traditionally been not to compress the board to the degree that you "oil can" it, or push it past flat to concave (from the top).  If the board does not have adequate crown then you replace the board.  Trying to rebuild crown is usually not very effective (or worth the effort).

The Pythagorean method outlined is one way to put a practical limit on down bearing settings.  It requires measuring the crown (not always so easy) and then determining at what bearing the board will go flat.  Keep in mind that downbeaing never gets to zero if the bearing is uniformly and positively set to begin with.  If you understand the mathematical idea of "limits" you will have a better sense as to why.  That's not to say that we don't see boards with negative bearing somewhere, but that must be because the bearing is positive somewhere else.  The bearing aggregate across the entire board must always be positive if it starts positive.

All that being said, the WNG perimeter bolts are a godsend for tweaking the bearing in situ and I am a strong advocate of their use whether it's a new board or restringing over an old one.  As Gravagne pionted out, by creating a small recess in the seating area of the perimeter bolt (usually about 6 mm is enough) you can avoid any problems that arise from it bottoming out before your desired settings are achieved, or before the plate contacts the board directly.  Crating a guide for the forstner bit to keep it aligned is very simple and I'm glad to share my method if someone is interested.  

THE PIANO ITS ACOUSTICS BY W. V. McFERRIN 1972↑

Might be a little off topic，I also have similar problem

 actually I still don't understand what level of down bearing is best.

Soundboard tension, down bearing, string tension, what's the most rational relationship between

These three should be considered comprehensively, right?These three should be considered comprehensively, right?

All these calculations are still based on the state of the soundboard. The state of the soundboard is the basis of these calculations. Can I understand it this way?

Therefore, according to the state of the soundboard, calculate the tension of the soundboard, adjust the relative height of the piano cast iron plate, and fine-tune the relative height of the cast iron plate (the height of Duplex-Skalen) according to the down bearing.

Maybe there is no need to go to so much trouble and just adjust the relative height of the cast iron plate and Duplex-Skalen according to the down bearing, right

I've read about people who simulate down pressure of strings on the soundboard prior to getting downbearing measurements for new bridge cap on either a new soundboard or even an old one if original measurements are slightly adjusted or if many shims were added to an old board. I haven't found any more information about specific ways this down pressure can be d. Are weights added to the board? Can you use the plate struts with wedges/jacks between the soundboard and plate strut? Any description, articles, or pictures you can share would be very much appreciated. Thank you!

Mr. David Love,I'd really like to know how you do it. If you can, I'd like to see your method.

Also I want to ask

The scale design excel table you uploaded before，Looks good, but some parts are hard to understand as I'm having a hard time finding anyone to ask about this,Excel sheet about the string part will measure the input data, the other parts are automatically calculated based on the string data, or do I need to measure again, about the part of the soundboard, I do not know how to measure, where to measure

Rib Scale Analysis/scale design

I sent you an email, but you didn't reply. If necessary, I will send you two books hoping to help with design optimization.

If you can, please take a look at the email I sent you on September 16, 2023.

Z Huang wrote: I still don't understand what level of down bearing is best. Soundboard tension, down bearing, string tension, what's the most rational relationship between. These three should be considered comprehensively, right? These three should be considered comprehensively, right? All these calculations are still based on the state of the soundboard. The state of the soundboard is the basis of these calculations. Can I understand it this way? Therefore, according to the state of the soundboard, calculate the tension of the soundboard, adjust the relative height of the piano cast iron plate, and fine-tune the relative height of the cast iron plate (the height of Duplex-Skalen) according to the down bearing.

Ask 10 different techs and you'll probably get 10 different answers.  But the short answer is yes, all these things should be considered comprehensively.  Typically, when a soundboard is being designed, the total downbearing is taken into consideration when designing the load bearing properties (i.e. the rib scale) to support the load.  The basic idea is that it must support the load but not be too stiff or too massive or the energy from the strings won't be able to move it adequately to generate ample enough pressure waves in the air and the piano will lack power, even if it exhibits good sustain.

Typically, the boards have been designed to compress about 50-60% under load.  That compression stiffens the board effectively without building in additional mass in, say, the ribs or the panel.  Each soundboard designer will develop their own standard and that % can vary with a number of things including string tensions, downbearing settings, amount of crown, personal impedance preferences etc.  Each one should be considered before making a final call and all these numbers come about with some testing, though there are general guidelines.  

On older soundboards the typical approach is to compress it as much as you can to try and achieve the requisite stiffness, as close as you had before, that has been lost due to age and accompanying loss of crown.  The limit has traditionally been not to compress the board to the degree that you "oil can" it, or push it past flat to concave (from the top).  If the board does not have adequate crown then you replace the board.  Trying to rebuild crown is usually not very effective (or worth the effort).

The Pythagorean method outlined is one way to put a practical limit on down bearing settings.  It requires measuring the crown (not always so easy) and then determining at what bearing the board will go flat.  Keep in mind that downbeaing never gets to zero if the bearing is uniformly and positively set to begin with.  If you understand the mathematical idea of "limits" you will have a better sense as to why.  That's not to say that we don't see boards with negative bearing somewhere, but that must be because the bearing is positive somewhere else.  The bearing aggregate across the entire board must always be positive if it starts positive.

All that being said, the WNG perimeter bolts are a godsend for tweaking the bearing in situ and I am a strong advocate of their use whether it's a new board or restringing over an old one.  As Gravagne pionted out, by creating a small recess in the seating area of the perimeter bolt (usually about 6 mm is enough) you can avoid any problems that arise from it bottoming out before your desired settings are achieved, or before the plate contacts the board directly.  Crating a guide for the forstner bit to keep it aligned is very simple and I'm glad to share my method if someone is interested.  

THE PIANO ITS ACOUSTICS BY W. V. McFERRIN 1972↑

Might be a little off topic，I also have similar problem

 actually I still don't understand what level of down bearing is best.

Soundboard tension, down bearing, string tension, what's the most rational relationship between

These three should be considered comprehensively, right?These three should be considered comprehensively, right?

All these calculations are still based on the state of the soundboard. The state of the soundboard is the basis of these calculations. Can I understand it this way?

Therefore, according to the state of the soundboard, calculate the tension of the soundboard, adjust the relative height of the piano cast iron plate, and fine-tune the relative height of the cast iron plate (the height of Duplex-Skalen) according to the down bearing.

Maybe there is no need to go to so much trouble and just adjust the relative height of the cast iron plate and Duplex-Skalen according to the down bearing, right

I've read about people who simulate down pressure of strings on the soundboard prior to getting downbearing measurements for new bridge cap on either a new soundboard or even an old one if original measurements are slightly adjusted or if many shims were added to an old board. I haven't found any more information about specific ways this down pressure can be d. Are weights added to the board? Can you use the plate struts with wedges/jacks between the soundboard and plate strut? Any description, articles, or pictures you can share would be very much appreciated. Thank you!

I did respond to several emails but our language differences, you said, made it difficult. 

When I put those spread sheets out I didn't mean to do a tutorial on them. They were for people who wanted to mess around with them for their own amusement or education. I decided I had no proprietary need to keep them secret in spite of the time and effort to develop them.  The input cells were marked by color, though I don't remember now what that was, it's been awhile. 

Anyway the scaling sheet shows you how to calculate tensions, you just need the speaking length and string diameters. The spread sheet did the rest for you. 

The rib scale part required only the input of the rib length, height, width and load per rib plus species data. Everything else was calculated.  How you determine the load per rib is a good question but more than I care to get into here. There have been countless discussions on this list about it though if you search the archives. Both Del Fandrich and Ron Nossaman, and maybe Nick Gravagne as well, participated. But beware as there are differences of opinion as to the best formulas to use regarding beams, fixed ends versus simple ends, for one (I believe fixed ends is correct). 

The spreadsheets for soundboards, btw, are more a way to quantify and track your methods and variables than they are a holy grail for how to design a soundboard. That, you have to figure out for yourself by building some and analyzing what you might do better on the next one. After a bunch of them you start to get a sense. 

Mr. David Love,I'd really like to know how you do it. If you can, I'd like to see your method.

Also I want to ask

The scale design excel table you uploaded before，Looks good, but some parts are hard to understand as I'm having a hard time finding anyone to ask about this,Excel sheet about the string part will measure the input data, the other parts are automatically calculated based on the string data, or do I need to measure again, about the part of the soundboard, I do not know how to measure, where to measure

Rib Scale Analysis/scale design

I sent you an email, but you didn't reply. If necessary, I will send you two books hoping to help with design optimization.

If you can, please take a look at the email I sent you on September 16, 2023.

Z Huang wrote: I still don't understand what level of down bearing is best. Soundboard tension, down bearing, string tension, what's the most rational relationship between. These three should be considered comprehensively, right? These three should be considered comprehensively, right? All these calculations are still based on the state of the soundboard. The state of the soundboard is the basis of these calculations. Can I understand it this way? Therefore, according to the state of the soundboard, calculate the tension of the soundboard, adjust the relative height of the piano cast iron plate, and fine-tune the relative height of the cast iron plate (the height of Duplex-Skalen) according to the down bearing.

Ask 10 different techs and you'll probably get 10 different answers.  But the short answer is yes, all these things should be considered comprehensively.  Typically, when a soundboard is being designed, the total downbearing is taken into consideration when designing the load bearing properties (i.e. the rib scale) to support the load.  The basic idea is that it must support the load but not be too stiff or too massive or the energy from the strings won't be able to move it adequately to generate ample enough pressure waves in the air and the piano will lack power, even if it exhibits good sustain.

Typically, the boards have been designed to compress about 50-60% under load.  That compression stiffens the board effectively without building in additional mass in, say, the ribs or the panel.  Each soundboard designer will develop their own standard and that % can vary with a number of things including string tensions, downbearing settings, amount of crown, personal impedance preferences etc.  Each one should be considered before making a final call and all these numbers come about with some testing, though there are general guidelines.  

On older soundboards the typical approach is to compress it as much as you can to try and achieve the requisite stiffness, as close as you had before, that has been lost due to age and accompanying loss of crown.  The limit has traditionally been not to compress the board to the degree that you "oil can" it, or push it past flat to concave (from the top).  If the board does not have adequate crown then you replace the board.  Trying to rebuild crown is usually not very effective (or worth the effort).

The Pythagorean method outlined is one way to put a practical limit on down bearing settings.  It requires measuring the crown (not always so easy) and then determining at what bearing the board will go flat.  Keep in mind that downbeaing never gets to zero if the bearing is uniformly and positively set to begin with.  If you understand the mathematical idea of "limits" you will have a better sense as to why.  That's not to say that we don't see boards with negative bearing somewhere, but that must be because the bearing is positive somewhere else.  The bearing aggregate across the entire board must always be positive if it starts positive.

All that being said, the WNG perimeter bolts are a godsend for tweaking the bearing in situ and I am a strong advocate of their use whether it's a new board or restringing over an old one.  As Gravagne pionted out, by creating a small recess in the seating area of the perimeter bolt (usually about 6 mm is enough) you can avoid any problems that arise from it bottoming out before your desired settings are achieved, or before the plate contacts the board directly.  Crating a guide for the forstner bit to keep it aligned is very simple and I'm glad to share my method if someone is interested.  

THE PIANO ITS ACOUSTICS BY W. V. McFERRIN 1972↑

Might be a little off topic，I also have similar problem

 actually I still don't understand what level of down bearing is best.

Soundboard tension, down bearing, string tension, what's the most rational relationship between

These three should be considered comprehensively, right?These three should be considered comprehensively, right?

All these calculations are still based on the state of the soundboard. The state of the soundboard is the basis of these calculations. Can I understand it this way?

Therefore, according to the state of the soundboard, calculate the tension of the soundboard, adjust the relative height of the piano cast iron plate, and fine-tune the relative height of the cast iron plate (the height of Duplex-Skalen) according to the down bearing.

Maybe there is no need to go to so much trouble and just adjust the relative height of the cast iron plate and Duplex-Skalen according to the down bearing, right

I've read about people who simulate down pressure of strings on the soundboard prior to getting downbearing measurements for new bridge cap on either a new soundboard or even an old one if original measurements are slightly adjusted or if many shims were added to an old board. I haven't found any more information about specific ways this down pressure can be d. Are weights added to the board? Can you use the plate struts with wedges/jacks between the soundboard and plate strut? Any description, articles, or pictures you can share would be very much appreciated. Thank you!

Z Huang wrote: I still don't understand what level of down bearing is best. Soundboard tension, down bearing, string tension, what's the most rational relationship between. These three should be considered comprehensively, right? These three should be considered comprehensively, right? All these calculations are still based on the state of the soundboard. The state of the soundboard is the basis of these calculations. Can I understand it this way? Therefore, according to the state of the soundboard, calculate the tension of the soundboard, adjust the relative height of the piano cast iron plate, and fine-tune the relative height of the cast iron plate (the height of Duplex-Skalen) according to the down bearing.

Ask 10 different techs and you'll probably get 10 different answers.  But the short answer is yes, all these things should be considered comprehensively.  Typically, when a soundboard is being designed, the total downbearing is taken into consideration when designing the load bearing properties (i.e. the rib scale) to support the load.  The basic idea is that it must support the load but not be too stiff or too massive or the energy from the strings won't be able to move it adequately to generate ample enough pressure waves in the air and the piano will lack power, even if it exhibits good sustain.

Typically, the boards have been designed to compress about 50-60% under load.  That compression stiffens the board effectively without building in additional mass in, say, the ribs or the panel.  Each soundboard designer will develop their own standard and that % can vary with a number of things including string tensions, downbearing settings, amount of crown, personal impedance preferences etc.  Each one should be considered before making a final call and all these numbers come about with some testing, though there are general guidelines.  

On older soundboards the typical approach is to compress it as much as you can to try and achieve the requisite stiffness, as close as you had before, that has been lost due to age and accompanying loss of crown.  The limit has traditionally been not to compress the board to the degree that you "oil can" it, or push it past flat to concave (from the top).  If the board does not have adequate crown then you replace the board.  Trying to rebuild crown is usually not very effective (or worth the effort).

The Pythagorean method outlined is one way to put a practical limit on down bearing settings.  It requires measuring the crown (not always so easy) and then determining at what bearing the board will go flat.  Keep in mind that downbeaing never gets to zero if the bearing is uniformly and positively set to begin with.  If you understand the mathematical idea of "limits" you will have a better sense as to why.  That's not to say that we don't see boards with negative bearing somewhere, but that must be because the bearing is positive somewhere else.  The bearing aggregate across the entire board must always be positive if it starts positive.

All that being said, the WNG perimeter bolts are a godsend for tweaking the bearing in situ and I am a strong advocate of their use whether it's a new board or restringing over an old one.  As Gravagne pionted out, by creating a small recess in the seating area of the perimeter bolt (usually about 6 mm is enough) you can avoid any problems that arise from it bottoming out before your desired settings are achieved, or before the plate contacts the board directly.  Crating a guide for the forstner bit to keep it aligned is very simple and I'm glad to share my method if someone is interested.  

THE PIANO ITS ACOUSTICS BY W. V. McFERRIN 1972↑

Might be a little off topic，I also have similar problem

 actually I still don't understand what level of down bearing is best.

Soundboard tension, down bearing, string tension, what's the most rational relationship between

These three should be considered comprehensively, right?These three should be considered comprehensively, right?

All these calculations are still based on the state of the soundboard. The state of the soundboard is the basis of these calculations. Can I understand it this way?

Therefore, according to the state of the soundboard, calculate the tension of the soundboard, adjust the relative height of the piano cast iron plate, and fine-tune the relative height of the cast iron plate (the height of Duplex-Skalen) according to the down bearing.

Maybe there is no need to go to so much trouble and just adjust the relative height of the cast iron plate and Duplex-Skalen according to the down bearing, right

I've read about people who simulate down pressure of strings on the soundboard prior to getting downbearing measurements for new bridge cap on either a new soundboard or even an old one if original measurements are slightly adjusted or if many shims were added to an old board. I haven't found any more information about specific ways this down pressure can be d. Are weights added to the board? Can you use the plate struts with wedges/jacks between the soundboard and plate strut? Any description, articles, or pictures you can share would be very much appreciated. Thank you!

David Love and Others,

I do not believe the intent of the WN&G plate perimeter bolts is to set downbearing on a soundboard. They are intended to capture the elevation of a plate above the soundboard once the desired downbearing has been achieved between the height of the bridges and the elevation(s) of the hitch pin panels on the plate. This is exactly what is performed at the Mason & Hamlin factory, utilizing the WN&G plate bolts.

Using these bolts to "set" downbearing will produce (only) a predominantly vertical global movement. It is common practice in piano manufacture and rebuilding to set different amounts of downbearing at different locations across the bridge caps. Adjusting a plate globally in the vertical plane (e.g.using the WN&G plate bolts) will not acheive this goal. One area may improve to the detriment of another, and vice versa.

I respectfully understand where you're going with this discussion, but it may not be wise, or completely thorough, to suggest using any plate suspension system to finesse downbearing. This must always be done by either adjusting (planing) the heights of the bridges relative to the plate elevation, or by using a vertical hitch pin whereby the strings me be slid up and down the pin to adjust string pressure on the soundboard from one area to another irrespective of global plate elevation.

Z Huang wrote: I still don't understand what level of down bearing is best. Soundboard tension, down bearing, string tension, what's the most rational relationship between. These three should be considered comprehensively, right? These three should be considered comprehensively, right? All these calculations are still based on the state of the soundboard. The state of the soundboard is the basis of these calculations. Can I understand it this way? Therefore, according to the state of the soundboard, calculate the tension of the soundboard, adjust the relative height of the piano cast iron plate, and fine-tune the relative height of the cast iron plate (the height of Duplex-Skalen) according to the down bearing.

Ask 10 different techs and you'll probably get 10 different answers.  But the short answer is yes, all these things should be considered comprehensively.  Typically, when a soundboard is being designed, the total downbearing is taken into consideration when designing the load bearing properties (i.e. the rib scale) to support the load.  The basic idea is that it must support the load but not be too stiff or too massive or the energy from the strings won't be able to move it adequately to generate ample enough pressure waves in the air and the piano will lack power, even if it exhibits good sustain.

Typically, the boards have been designed to compress about 50-60% under load.  That compression stiffens the board effectively without building in additional mass in, say, the ribs or the panel.  Each soundboard designer will develop their own standard and that % can vary with a number of things including string tensions, downbearing settings, amount of crown, personal impedance preferences etc.  Each one should be considered before making a final call and all these numbers come about with some testing, though there are general guidelines.  

On older soundboards the typical approach is to compress it as much as you can to try and achieve the requisite stiffness, as close as you had before, that has been lost due to age and accompanying loss of crown.  The limit has traditionally been not to compress the board to the degree that you "oil can" it, or push it past flat to concave (from the top).  If the board does not have adequate crown then you replace the board.  Trying to rebuild crown is usually not very effective (or worth the effort).

The Pythagorean method outlined is one way to put a practical limit on down bearing settings.  It requires measuring the crown (not always so easy) and then determining at what bearing the board will go flat.  Keep in mind that downbeaing never gets to zero if the bearing is uniformly and positively set to begin with.  If you understand the mathematical idea of "limits" you will have a better sense as to why.  That's not to say that we don't see boards with negative bearing somewhere, but that must be because the bearing is positive somewhere else.  The bearing aggregate across the entire board must always be positive if it starts positive.

All that being said, the WNG perimeter bolts are a godsend for tweaking the bearing in situ and I am a strong advocate of their use whether it's a new board or restringing over an old one.  As Gravagne pionted out, by creating a small recess in the seating area of the perimeter bolt (usually about 6 mm is enough) you can avoid any problems that arise from it bottoming out before your desired settings are achieved, or before the plate contacts the board directly.  Crating a guide for the forstner bit to keep it aligned is very simple and I'm glad to share my method if someone is interested.  

THE PIANO ITS ACOUSTICS BY W. V. McFERRIN 1972↑

Might be a little off topic，I also have similar problem

 actually I still don't understand what level of down bearing is best.

Soundboard tension, down bearing, string tension, what's the most rational relationship between

These three should be considered comprehensively, right?These three should be considered comprehensively, right?

All these calculations are still based on the state of the soundboard. The state of the soundboard is the basis of these calculations. Can I understand it this way?

Therefore, according to the state of the soundboard, calculate the tension of the soundboard, adjust the relative height of the piano cast iron plate, and fine-tune the relative height of the cast iron plate (the height of Duplex-Skalen) according to the down bearing.

Maybe there is no need to go to so much trouble and just adjust the relative height of the cast iron plate and Duplex-Skalen according to the down bearing, right

I've read about people who simulate down pressure of strings on the soundboard prior to getting downbearing measurements for new bridge cap on either a new soundboard or even an old one if original measurements are slightly adjusted or if many shims were added to an old board. I haven't found any more information about specific ways this down pressure can be d. Are weights added to the board? Can you use the plate struts with wedges/jacks between the soundboard and plate strut? Any description, articles, or pictures you can share would be very much appreciated. Thank you!

I think what I said was that they are " a godsend for tweaking the bearing in situ". That's a far cry from using them to set bearing. They are, however, used to set the plate height and function in the place of soundboard dowels. Downswing is more a function of bridge height, though there are some other factors like aliquots etc

David Love and Others,

I do not believe the intent of the WN&G plate perimeter bolts is to set downbearing on a soundboard. They are intended to capture the elevation of a plate above the soundboard once the desired downbearing has been achieved between the height of the bridges and the elevation(s) of the hitch pin panels on the plate. This is exactly what is performed at the Mason & Hamlin factory, utilizing the WN&G plate bolts.

Using these bolts to "set" downbearing will produce (only) a predominantly vertical global movement. It is common practice in piano manufacture and rebuilding to set different amounts of downbearing at different locations across the bridge caps. Adjusting a plate globally in the vertical plane (e.g.using the WN&G plate bolts) will not acheive this goal. One area may improve to the detriment of another, and vice versa.

I respectfully understand where you're going with this discussion, but it may not be wise, or completely thorough, to suggest using any plate suspension system to finesse downbearing. This must always be done by either adjusting (planing) the heights of the bridges relative to the plate elevation, or by using a vertical hitch pin whereby the strings me be slid up and down the pin to adjust string pressure on the soundboard from one area to another irrespective of global plate elevation.

Z Huang wrote: I still don't understand what level of down bearing is best. Soundboard tension, down bearing, string tension, what's the most rational relationship between. These three should be considered comprehensively, right? These three should be considered comprehensively, right? All these calculations are still based on the state of the soundboard. The state of the soundboard is the basis of these calculations. Can I understand it this way? Therefore, according to the state of the soundboard, calculate the tension of the soundboard, adjust the relative height of the piano cast iron plate, and fine-tune the relative height of the cast iron plate (the height of Duplex-Skalen) according to the down bearing.

Ask 10 different techs and you'll probably get 10 different answers.  But the short answer is yes, all these things should be considered comprehensively.  Typically, when a soundboard is being designed, the total downbearing is taken into consideration when designing the load bearing properties (i.e. the rib scale) to support the load.  The basic idea is that it must support the load but not be too stiff or too massive or the energy from the strings won't be able to move it adequately to generate ample enough pressure waves in the air and the piano will lack power, even if it exhibits good sustain.

Typically, the boards have been designed to compress about 50-60% under load.  That compression stiffens the board effectively without building in additional mass in, say, the ribs or the panel.  Each soundboard designer will develop their own standard and that % can vary with a number of things including string tensions, downbearing settings, amount of crown, personal impedance preferences etc.  Each one should be considered before making a final call and all these numbers come about with some testing, though there are general guidelines.  

On older soundboards the typical approach is to compress it as much as you can to try and achieve the requisite stiffness, as close as you had before, that has been lost due to age and accompanying loss of crown.  The limit has traditionally been not to compress the board to the degree that you "oil can" it, or push it past flat to concave (from the top).  If the board does not have adequate crown then you replace the board.  Trying to rebuild crown is usually not very effective (or worth the effort).

The Pythagorean method outlined is one way to put a practical limit on down bearing settings.  It requires measuring the crown (not always so easy) and then determining at what bearing the board will go flat.  Keep in mind that downbeaing never gets to zero if the bearing is uniformly and positively set to begin with.  If you understand the mathematical idea of "limits" you will have a better sense as to why.  That's not to say that we don't see boards with negative bearing somewhere, but that must be because the bearing is positive somewhere else.  The bearing aggregate across the entire board must always be positive if it starts positive.

All that being said, the WNG perimeter bolts are a godsend for tweaking the bearing in situ and I am a strong advocate of their use whether it's a new board or restringing over an old one.  As Gravagne pionted out, by creating a small recess in the seating area of the perimeter bolt (usually about 6 mm is enough) you can avoid any problems that arise from it bottoming out before your desired settings are achieved, or before the plate contacts the board directly.  Crating a guide for the forstner bit to keep it aligned is very simple and I'm glad to share my method if someone is interested.  

THE PIANO ITS ACOUSTICS BY W. V. McFERRIN 1972↑

Might be a little off topic，I also have similar problem

 actually I still don't understand what level of down bearing is best.

Soundboard tension, down bearing, string tension, what's the most rational relationship between

These three should be considered comprehensively, right?These three should be considered comprehensively, right?

All these calculations are still based on the state of the soundboard. The state of the soundboard is the basis of these calculations. Can I understand it this way?

Therefore, according to the state of the soundboard, calculate the tension of the soundboard, adjust the relative height of the piano cast iron plate, and fine-tune the relative height of the cast iron plate (the height of Duplex-Skalen) according to the down bearing.

Maybe there is no need to go to so much trouble and just adjust the relative height of the cast iron plate and Duplex-Skalen according to the down bearing, right

I've read about people who simulate down pressure of strings on the soundboard prior to getting downbearing measurements for new bridge cap on either a new soundboard or even an old one if original measurements are slightly adjusted or if many shims were added to an old board. I haven't found any more information about specific ways this down pressure can be d. Are weights added to the board? Can you use the plate struts with wedges/jacks between the soundboard and plate strut? Any description, articles, or pictures you can share would be very much appreciated. Thank you!

David Love (reply to your post #14),

Yes, I understand your position. I was merely stating some facts as I see them about setting downward string pressure on soundboards. For the experienced, this obvious - not all participants of this discussion may be experienced. What I think we need to be careful of is implying that the WN&G plate bolts can be used to "set bearing". Briefly, the simple visual analogy is a car's hood. It hinges up near the windshield. As the hood closes it becomes nearer the rear of the engine (and would apply more pressure) long before it nears the grill on the front of the car.

A piano plate is buckled to the pinblock, and this is an elevation we do not wish to alter - primarily for proper action performance. It is a hinge point. If we want to bend the plate (I don't), we can raise or lower the rear of the plate to "set downbearing". The condition will arise immediately that when the plate is lowered, for instance, the downbearing will increase dramatically at note 88 long before any change is affected at note 1. All the notes in between are at the unrefined mercy of the procedure.

On the general topic of how much downbearing is "just right" for any piano, bear in mind manufacturers build oodles of pianos as experiments (in spite of the best mathematic calculations), changing only one element of the downbearing equation in each experiment, and then they aurally evaluate each experiment. They enjoy the luxury of being able do this. As a rebuilder, we attempt to do the same experiments, only with less candidates to experiment with. Ultimately we just have to buckle down and rebuild lots of pianos to come up with a soundboard structure and a downbearing formula that gives us the results we're hoping for. Unfortunately life is too short for the small shop operator - we rebuild hundreds of pianos; manufacturers build hundreds of thousands of pianos. Nonetheless, everyone participating in this discussion, and beyond, does the best he/she can in the time that is granted to us! :-)

I think what I said was that they are " a godsend for tweaking the bearing in situ". That's a far cry from using them to set bearing. They are, however, used to set the plate height and function in the place of soundboard dowels. Downswing is more a function of bridge height, though there are some other factors like aliquots etc

David Love and Others,

I do not believe the intent of the WN&G plate perimeter bolts is to set downbearing on a soundboard. They are intended to capture the elevation of a plate above the soundboard once the desired downbearing has been achieved between the height of the bridges and the elevation(s) of the hitch pin panels on the plate. This is exactly what is performed at the Mason & Hamlin factory, utilizing the WN&G plate bolts.

Using these bolts to "set" downbearing will produce (only) a predominantly vertical global movement. It is common practice in piano manufacture and rebuilding to set different amounts of downbearing at different locations across the bridge caps. Adjusting a plate globally in the vertical plane (e.g.using the WN&G plate bolts) will not acheive this goal. One area may improve to the detriment of another, and vice versa.

I respectfully understand where you're going with this discussion, but it may not be wise, or completely thorough, to suggest using any plate suspension system to finesse downbearing. This must always be done by either adjusting (planing) the heights of the bridges relative to the plate elevation, or by using a vertical hitch pin whereby the strings me be slid up and down the pin to adjust string pressure on the soundboard from one area to another irrespective of global plate elevation.

Z Huang wrote: I still don't understand what level of down bearing is best. Soundboard tension, down bearing, string tension, what's the most rational relationship between. These three should be considered comprehensively, right? These three should be considered comprehensively, right? All these calculations are still based on the state of the soundboard. The state of the soundboard is the basis of these calculations. Can I understand it this way? Therefore, according to the state of the soundboard, calculate the tension of the soundboard, adjust the relative height of the piano cast iron plate, and fine-tune the relative height of the cast iron plate (the height of Duplex-Skalen) according to the down bearing.

Ask 10 different techs and you'll probably get 10 different answers.  But the short answer is yes, all these things should be considered comprehensively.  Typically, when a soundboard is being designed, the total downbearing is taken into consideration when designing the load bearing properties (i.e. the rib scale) to support the load.  The basic idea is that it must support the load but not be too stiff or too massive or the energy from the strings won't be able to move it adequately to generate ample enough pressure waves in the air and the piano will lack power, even if it exhibits good sustain.

Typically, the boards have been designed to compress about 50-60% under load.  That compression stiffens the board effectively without building in additional mass in, say, the ribs or the panel.  Each soundboard designer will develop their own standard and that % can vary with a number of things including string tensions, downbearing settings, amount of crown, personal impedance preferences etc.  Each one should be considered before making a final call and all these numbers come about with some testing, though there are general guidelines.  

On older soundboards the typical approach is to compress it as much as you can to try and achieve the requisite stiffness, as close as you had before, that has been lost due to age and accompanying loss of crown.  The limit has traditionally been not to compress the board to the degree that you "oil can" it, or push it past flat to concave (from the top).  If the board does not have adequate crown then you replace the board.  Trying to rebuild crown is usually not very effective (or worth the effort).

The Pythagorean method outlined is one way to put a practical limit on down bearing settings.  It requires measuring the crown (not always so easy) and then determining at what bearing the board will go flat.  Keep in mind that downbeaing never gets to zero if the bearing is uniformly and positively set to begin with.  If you understand the mathematical idea of "limits" you will have a better sense as to why.  That's not to say that we don't see boards with negative bearing somewhere, but that must be because the bearing is positive somewhere else.  The bearing aggregate across the entire board must always be positive if it starts positive.

All that being said, the WNG perimeter bolts are a godsend for tweaking the bearing in situ and I am a strong advocate of their use whether it's a new board or restringing over an old one.  As Gravagne pionted out, by creating a small recess in the seating area of the perimeter bolt (usually about 6 mm is enough) you can avoid any problems that arise from it bottoming out before your desired settings are achieved, or before the plate contacts the board directly.  Crating a guide for the forstner bit to keep it aligned is very simple and I'm glad to share my method if someone is interested.  

THE PIANO ITS ACOUSTICS BY W. V. McFERRIN 1972↑

Might be a little off topic，I also have similar problem

 actually I still don't understand what level of down bearing is best.

Soundboard tension, down bearing, string tension, what's the most rational relationship between

These three should be considered comprehensively, right?These three should be considered comprehensively, right?

All these calculations are still based on the state of the soundboard. The state of the soundboard is the basis of these calculations. Can I understand it this way?

Therefore, according to the state of the soundboard, calculate the tension of the soundboard, adjust the relative height of the piano cast iron plate, and fine-tune the relative height of the cast iron plate (the height of Duplex-Skalen) according to the down bearing.

Maybe there is no need to go to so much trouble and just adjust the relative height of the cast iron plate and Duplex-Skalen according to the down bearing, right

I've read about people who simulate down pressure of strings on the soundboard prior to getting downbearing measurements for new bridge cap on either a new soundboard or even an old one if original measurements are slightly adjusted or if many shims were added to an old board. I haven't found any more information about specific ways this down pressure can be d. Are weights added to the board? Can you use the plate struts with wedges/jacks between the soundboard and plate strut? Any description, articles, or pictures you can share would be very much appreciated. Thank you!

Certainly one should exercise caution that what is said may be misinterpreted and used against you later 🤪. Especially when it comes to plate bending.

But the reality is that plates do flex and even the best efforts to avoid any and all plate flexing are probably futile and without real risk.  Even Steinway uses nose bolts to tweak bearing by bending the plate (usually down) while the official position, and rightfully so to avoid what you refer to, is that plates should not be flexed.

I have made *small* adjustments to the bearing on several occasions with the benefit of WNG plate bolts and still sleep soundly to the degree that my aging sleep cycles allow. But we certainly don't want to rely on that method as a means to compensate for poor bridge cap or pinblock accuracy. 

Happy Thanksgiving all.

David Love (reply to your post #14),

Yes, I understand your position. I was merely stating some facts as I see them about setting downward string pressure on soundboards. For the experienced, this obvious - not all participants of this discussion may be experienced. What I think we need to be careful of is implying that the WN&G plate bolts can be used to "set bearing". Briefly, the simple visual analogy is a car's hood. It hinges up near the windshield. As the hood closes it becomes nearer the rear of the engine (and would apply more pressure) long before it nears the grill on the front of the car.

A piano plate is buckled to the pinblock, and this is an elevation we do not wish to alter - primarily for proper action performance. It is a hinge point. If we want to bend the plate (I don't), we can raise or lower the rear of the plate to "set downbearing". The condition will arise immediately that when the plate is lowered, for instance, the downbearing will increase dramatically at note 88 long before any change is affected at note 1. All the notes in between are at the unrefined mercy of the procedure.

On the general topic of how much downbearing is "just right" for any piano, bear in mind manufacturers build oodles of pianos as experiments (in spite of the best mathematic calculations), changing only one element of the downbearing equation in each experiment, and then they aurally evaluate each experiment. They enjoy the luxury of being able do this. As a rebuilder, we attempt to do the same experiments, only with less candidates to experiment with. Ultimately we just have to buckle down and rebuild lots of pianos to come up with a soundboard structure and a downbearing formula that gives us the results we're hoping for. Unfortunately life is too short for the small shop operator - we rebuild hundreds of pianos; manufacturers build hundreds of thousands of pianos. Nonetheless, everyone participating in this discussion, and beyond, does the best he/she can in the time that is granted to us! :-)

I think what I said was that they are " a godsend for tweaking the bearing in situ". That's a far cry from using them to set bearing. They are, however, used to set the plate height and function in the place of soundboard dowels. Downswing is more a function of bridge height, though there are some other factors like aliquots etc

David Love and Others,

I do not believe the intent of the WN&G plate perimeter bolts is to set downbearing on a soundboard. They are intended to capture the elevation of a plate above the soundboard once the desired downbearing has been achieved between the height of the bridges and the elevation(s) of the hitch pin panels on the plate. This is exactly what is performed at the Mason & Hamlin factory, utilizing the WN&G plate bolts.

Using these bolts to "set" downbearing will produce (only) a predominantly vertical global movement. It is common practice in piano manufacture and rebuilding to set different amounts of downbearing at different locations across the bridge caps. Adjusting a plate globally in the vertical plane (e.g.using the WN&G plate bolts) will not acheive this goal. One area may improve to the detriment of another, and vice versa.

I respectfully understand where you're going with this discussion, but it may not be wise, or completely thorough, to suggest using any plate suspension system to finesse downbearing. This must always be done by either adjusting (planing) the heights of the bridges relative to the plate elevation, or by using a vertical hitch pin whereby the strings me be slid up and down the pin to adjust string pressure on the soundboard from one area to another irrespective of global plate elevation.

Z Huang wrote: I still don't understand what level of down bearing is best. Soundboard tension, down bearing, string tension, what's the most rational relationship between. These three should be considered comprehensively, right? These three should be considered comprehensively, right? All these calculations are still based on the state of the soundboard. The state of the soundboard is the basis of these calculations. Can I understand it this way? Therefore, according to the state of the soundboard, calculate the tension of the soundboard, adjust the relative height of the piano cast iron plate, and fine-tune the relative height of the cast iron plate (the height of Duplex-Skalen) according to the down bearing.

Ask 10 different techs and you'll probably get 10 different answers.  But the short answer is yes, all these things should be considered comprehensively.  Typically, when a soundboard is being designed, the total downbearing is taken into consideration when designing the load bearing properties (i.e. the rib scale) to support the load.  The basic idea is that it must support the load but not be too stiff or too massive or the energy from the strings won't be able to move it adequately to generate ample enough pressure waves in the air and the piano will lack power, even if it exhibits good sustain.

Typically, the boards have been designed to compress about 50-60% under load.  That compression stiffens the board effectively without building in additional mass in, say, the ribs or the panel.  Each soundboard designer will develop their own standard and that % can vary with a number of things including string tensions, downbearing settings, amount of crown, personal impedance preferences etc.  Each one should be considered before making a final call and all these numbers come about with some testing, though there are general guidelines.  

On older soundboards the typical approach is to compress it as much as you can to try and achieve the requisite stiffness, as close as you had before, that has been lost due to age and accompanying loss of crown.  The limit has traditionally been not to compress the board to the degree that you "oil can" it, or push it past flat to concave (from the top).  If the board does not have adequate crown then you replace the board.  Trying to rebuild crown is usually not very effective (or worth the effort).

The Pythagorean method outlined is one way to put a practical limit on down bearing settings.  It requires measuring the crown (not always so easy) and then determining at what bearing the board will go flat.  Keep in mind that downbeaing never gets to zero if the bearing is uniformly and positively set to begin with.  If you understand the mathematical idea of "limits" you will have a better sense as to why.  That's not to say that we don't see boards with negative bearing somewhere, but that must be because the bearing is positive somewhere else.  The bearing aggregate across the entire board must always be positive if it starts positive.

All that being said, the WNG perimeter bolts are a godsend for tweaking the bearing in situ and I am a strong advocate of their use whether it's a new board or restringing over an old one.  As Gravagne pionted out, by creating a small recess in the seating area of the perimeter bolt (usually about 6 mm is enough) you can avoid any problems that arise from it bottoming out before your desired settings are achieved, or before the plate contacts the board directly.  Crating a guide for the forstner bit to keep it aligned is very simple and I'm glad to share my method if someone is interested.  

THE PIANO ITS ACOUSTICS BY W. V. McFERRIN 1972↑

Might be a little off topic，I also have similar problem

 actually I still don't understand what level of down bearing is best.

Soundboard tension, down bearing, string tension, what's the most rational relationship between

These three should be considered comprehensively, right?These three should be considered comprehensively, right?

All these calculations are still based on the state of the soundboard. The state of the soundboard is the basis of these calculations. Can I understand it this way?

Therefore, according to the state of the soundboard, calculate the tension of the soundboard, adjust the relative height of the piano cast iron plate, and fine-tune the relative height of the cast iron plate (the height of Duplex-Skalen) according to the down bearing.

Maybe there is no need to go to so much trouble and just adjust the relative height of the cast iron plate and Duplex-Skalen according to the down bearing, right

I've read about people who simulate down pressure of strings on the soundboard prior to getting downbearing measurements for new bridge cap on either a new soundboard or even an old one if original measurements are slightly adjusted or if many shims were added to an old board. I haven't found any more information about specific ways this down pressure can be d. Are weights added to the board? Can you use the plate struts with wedges/jacks between the soundboard and plate strut? Any description, articles, or pictures you can share would be very much appreciated. Thank you!