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#2102803 - 06/15/13 07:30 AM Re: Does a soundboard improve with aging? [Re: Mark R.]
jim ialeggio Offline
500 Post Club Member

Registered: 06/03/05
Posts: 731
Loc: shirley, MA
Originally Posted By: Mark R.
Jim, this latter case, of premature failure on the showroom floor, is difficult for me to picture. Could you describe the nature of the failure?

Boards constructed using high levels of compression can do this...Sometimes the board inadvertently has dried too much before rib assembly. When the ribs are glued on these panels, as the board takes up normal ambient moisture it compresses parts of the board which were already darn close to the point of cellular collapse, past the point of no return. This can happen after just a few moisture cycles.

Jim Ialeggio
_________________________
Jim Ialeggio
www.grandpianosolutions.com
advanced soundboard and action redesigns
978 425-9026
Shirley Center, MA

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#2102810 - 06/15/13 07:49 AM Re: Does a soundboard improve with aging? [Re: phacke]
jim ialeggio Offline
500 Post Club Member

Registered: 06/03/05
Posts: 731
Loc: shirley, MA
Originally Posted By: phacke
Have you observed, and can you generalize what area(s) of the soundboard in the piano might exhibit compression beyond the elastic limit and yield should the relative humidity go way up?

The panel is about 4ft wide at some points. Wood expansion happens across the grain, ie across this 4ft expanse. With changes in EMC wood expansion across a large cross grain span is significant. Normally, the spruce which is quite elastic, takes up a fair amount of that expansion by compressing small amounts throughout the entire width of the panel. If the board's EMC was too low when the ribs were glued on, the board is already compressed and held in that compressed state, offering little scope for further compression without irreversible cellular collapse.

So the compression happens in the field of the panel. The failure is seen often but not limited to joints between the glued up boards that make up the panel. After compressing the wood past its compressive limit, the crushed cells have lost elasticity. When the board shrinks at the next cycle, the no longer elastic portions have to give somehow, and they split.

This might or might not kill the board, depending on whether the manufacturer was depending on the compression of the panel to be the essential component of the boards stiffness or whether the ribs were sufficient to supply adequate stiffness.

Jim Ialeggio
_________________________
Jim Ialeggio
www.grandpianosolutions.com
advanced soundboard and action redesigns
978 425-9026
Shirley Center, MA

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#2102847 - 06/15/13 10:19 AM Re: Does a soundboard improve with aging? [Re: jim ialeggio]
Olek Offline
7000 Post Club Member

Registered: 03/14/08
Posts: 7904
Loc: France
Originally Posted By: jim ialeggio
Originally Posted By: Mark R.
Jim, this latter case, of premature failure on the showroom floor, is difficult for me to picture. Could you describe the nature of the failure?

Boards constructed using high levels of compression can do this...Sometimes the board inadvertently has dried too much before rib assembly. When the ribs are glued on these panels, as the board takes up normal ambient moisture it compresses parts of the board which were already darn close to the point of cellular collapse, past the point of no return. This can happen after just a few moisture cycles.

Jim Ialeggio


I am sorry Jim but your logic does not seem to be correct. When the wood take moisture it release from compression, on the glued part.

If a panel that is too much dried suffers when moisture level raise it is not of too much compression, or I translate badly.

What said Mr Steingraeber is that the wood cells could be weakened by too much drying. (hence his drying level I guess about 5.5% EMC)

The compression cannot be too high with ribbing. expansion, eventually (on the upper surface of the panel) .

I could believe that a too much dried panel could have a hard time to accept compression under a heavy curve, as if 8 mm crown is used in the caul for instance, but then when the moisture release the wood expands.

The amount of compression that the spruce may accept without bypassing its elastic limit can certainly be computed.








Edited by Olek (06/15/13 11:55 AM)
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#2102865 - 06/15/13 11:24 AM Re: Does a soundboard improve with aging? [Re: Olek]
jim ialeggio Offline
500 Post Club Member

Registered: 06/03/05
Posts: 731
Loc: shirley, MA
Originally Posted By: Olek
I am sorry Jim but your logic does not seem to be correct. When the wood take moisture it release from compression, on the glued part.

If a panel that is too much dried suffers, it is not of too much compression.

I disagree Isaac,

The board does not return to its previous state when ambient moisture is re-introduced. The ribs, which are glued across the grain, restrain the panel's return to its previous free state. So as the panel picks up ambient moisture, it expands. However, the expansion is resisted by the ribbing.

This resistance of the ribbing, combined with EMC induced expansion forces the panel into an unbalanced state of compression. It is unbalanced because the un-ribbed side of the panel is unequally restrained, forcing the panel into a crown.

Then, that unbalanced crown is forced into further compression by applying anywhere from 500lbs to over 1000lbs of downbearing.

Jim Ialeggio


Edited by jim ialeggio (06/15/13 03:59 PM)
Edit Reason: redundant sentences...sigh
_________________________
Jim Ialeggio
www.grandpianosolutions.com
advanced soundboard and action redesigns
978 425-9026
Shirley Center, MA

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#2102868 - 06/15/13 11:26 AM Re: Does a soundboard improve with aging? [Re: tdv]
Craig Hair Offline
Full Member

Registered: 06/03/11
Posts: 205
Loc: Holyoke, MA


It has been my experience that old soundboard material becomes stiffer over time, not more flexible. At the same time, the wood has become lighter from the loss of bound moisture other than water. These combined developments compliment one another, and result in a marked rise in the natural impedence of the wood. This rise manifests itself as an added clarity in the tonal response

In this way I would say that soundboard material improves with aging. Who would'nt use the most thoroughly aged wood for their boards? And, if the conditions for the piano are absolutely perfect, then I could imagine a board that sounds better with time, where the natural vibrancy of the wood might keep ahead of structural compromises. But everything goes against it.

As I see it, the soundboard is a driven system that relies on mechanical advantages to produce an acoustic effect. The closest mechano-acoustic cousin is the singing saw, with its large acoustic body, stressed into opposing springs, being activated by a small driver.; clearly a very efficient transduction model. The crowned board bucks against the rim, becoming a stiffer spring, with a higher natural impedance, and responds to the wire by reproducing the higher partials more clearly. The downbearing is there to ensure that the board gets bucked. If the mechanical relationships lessen, then the effect is lessened in turn.

In this way an old piano, with just a remnant of crown and bearing, may lack the power and the dynamic range provided by a robust crown/bearing, yet still exibit a tonal clarity so distinct that many choose to live with the downside, rather than risk losing it. This clarity, I believe, comes from the raised impedance of the wood, in total, making the best of a bad mechanical state. The bass section, responding the best to a lowered impedance, suffers the least. The high treble lives and dies by its crown. Like the saw, if there is not a springy tensioned interface, energy dissipates instantly. The break becomes pronounced as the mechanical founadions of each note,being drasticly different, have degraded in divergant fashion. We call it the bass fiddle to banjo effect. These are all mechanical failings due to the shrinkage of the wood. And even though loosening the board along the spine and belly rail allows you to push some crown back into the longest ribs.

And this does a lot to improve the break.

Nothing but a complete removal and reconstruction,however, can reestablish the mechanical foundations in the treble. These limitations have driven most decisions to replace.

With replacement, however, there is an unavoidable change in the imedance of the resonant material. It may solve all the mechanical problems in the board, but the basic voice of the piano will be changed. It may gain in power and balance, but the loss of age clarity obliterates a certain promptness and presence. As for myself, the clarity is worth the exta work involved in restoration over refabrication.

Old tonewood is stable and responsive but it is not indestructable. The annual shrinkage rate, something that never goes away, has slowed over a century to the point of being almost negligible. Stable not meaning dead, the wood still expands across the grain with enough strength to bow the ribs, though we do use curved caulding. Still, anything that would ruin a new board might damage one of these as well. All fully functioning pianos are deceptivly delicate and need environmental maintenance.

As far as the Strads go, musicians tell me that the difference lies in how the instruments play as well as how they sound. That they are so readily responsive that they are less work to play and easier to controll.




,
_________________________
Craig Hair
Hampshire Piano
Holyoke, MA

hampshirepiano.co
soundboardrecrown.com

If I seem slow, I simply must be stopped

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#2102881 - 06/15/13 12:05 PM Re: Does a soundboard improve with aging? [Re: jim ialeggio]
Olek Offline
7000 Post Club Member

Registered: 03/14/08
Posts: 7904
Loc: France
Originally Posted By: jim ialeggio
Originally Posted By: Olek
I am sorry Jim but your logic does not seem to be correct. When the wood take moisture it release from compression, on the glued part.

If a panel that is too much dried suffers, it is not of too much compression.

I disagree Isaac,

The board does not return to its previous state when ambient moisture is re-introduced. The ribs, which are glued across the grain, restrain the panel's return to its previous free state. So as the panel picks up ambient moisture, it expands. However, the expansion is resisted by the ribbing.

This resistance of the ribbing, combined with EMC induced expansion forces the panel into an unbalanced state of compression. The wood wants to return to its EMC appropriate dimension, but the ribs are restraining it. It is unbalanced because the un-ribbed side of the panel is unequally restrained. This unbalanced compression forces the board into a crown.

The existence of crown at all, in a compression board is a sypmtom that the board has both expanded from its dried state, but that it is also being restrained from assuming its pre-ribbed condition. Add to that that the panel is then glued to the rim, which further restrains the expansion of the panel.

It is the ribbing forcing the panel into the dried state reduced cross grain dimension that causes the compression as well as the creation of crown in a compression board. Then, that unbalanced crown is forced into further compression by applying anywhere from 500lbs to over 1000lbs of downbearing.

Jim Ialeggio


Yes Jim, the ribbing force compression on a yet reduced panel, then that drying acts as a protection against future cracks, also, as the wood, even if restrained have keep some reserve of expansion toward its original state.
If the panel is not dried enough ther seem to be less reserve, as I understand it.

I said that because you said the wood compress when the moisture is coming back. I am not sure of that point, it is retained, not crushed, if you see what I mean.
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#2102884 - 06/15/13 12:14 PM Re: Does a soundboard improve with aging? [Re: Craig Hair]
Olek Offline
7000 Post Club Member

Registered: 03/14/08
Posts: 7904
Loc: France
Originally Posted By: Craig Hair


It has been my experience that old soundboard material becomes stiffer over time, not more flexible. At the same time, the wood has become lighter from the loss of bound moisture other than water. These combined developments compliment one another, and result in a marked rise in the natural impedence of the wood. This rise manifests itself as an added clarity in the tonal response

In this way I would say that soundboard material improves with aging. Who would'nt use the most thoroughly aged wood for their boards? And, if the conditions for the piano are absolutely perfect, then I could imagine a board that sounds better with time, where the natural vibrancy of the wood might keep ahead of structural compromises. But everything goes against it.

As I see it, the soundboard is a driven system that relies on mechanical advantages to produce an acoustic effect. The closest mechano-acoustic cousin is the singing saw, with its large acoustic body, stressed into opposing springs, being activated by a small driver.; clearly a very efficient transduction model. The crowned board bucks against the rim, becoming a stiffer spring, with a higher natural impedance, and responds to the wire by reproducing the higher partials more clearly. The downbearing is there to ensure that the board gets bucked. If the mechanical relationships lessen, then the effect is lessened in turn.

In this way an old piano, with just a remnant of crown and bearing, may lack the power and the dynamic range provided by a robust crown/bearing, yet still exibit a tonal clarity so distinct that many choose to live with the downside, rather than risk losing it. This clarity, I believe, comes from the raised impedance of the wood, in total, making the best of a bad mechanical state. The bass section, responding the best to a lowered impedance, suffers the least. The high treble lives and dies by its crown. Like the saw, if there is not a springy tensioned interface, energy dissipates instantly. The break becomes pronounced as the mechanical founadions of each note,being drasticly different, have degraded in divergant fashion. We call it the bass fiddle to banjo effect. These are all mechanical failings due to the shrinkage of the wood. And even though loosening the board along the spine and belly rail allows you to push some crown back into the longest ribs.

And this does a lot to improve the break.

Nothing but a complete removal and reconstruction,however, can reestablish the mechanical foundations in the treble. These limitations have driven most decisions to replace.

With replacement, however, there is an unavoidable change in the imedance of the resonant material. It may solve all the mechanical problems in the board, but the basic voice of the piano will be changed. It may gain in power and balance, but the loss of age clarity obliterates a certain promptness and presence. As for myself, the clarity is worth the exta work involved in restoration over refabrication.

Old tonewood is stable and responsive but it is not indestructable. The annual shrinkage rate, something that never goes away, has slowed over a century to the point of being almost negligible. Stable not meaning dead, the wood still expands across the grain with enough strength to bow the ribs, though we do use curved caulding. Still, anything that would ruin a new board might damage one of these as well. All fully functioning pianos are deceptivly delicate and need environmental maintenance.

As far as the Strads go, musicians tell me that the difference lies in how the instruments play as well as how they sound. That they are so readily responsive that they are less work to play and easier to controll.




,


Hello Craig, thanks for the added points.

My experience (limited) shows that old soundboards does lower under new downbearing easily. sometime after 1-2 years, sometime as soon as the pressure is added.

I guess I see what you mean with some hardening (that is loss of elasticity, "old wood", "hard wood" is something that is known as a concept) then the loss of resiliency may come from the ribs more than from the panel. (or more precisely from the loss of constrain within the gluing of the structure, reducing of the panel, etc, depending , again, of the type of method used for ribbing )

I have hard time to believe that only the too little crown is impeding resistance to more downbearing that is encountered on some (most?) old boards. (the crown is not so much seen as structural resistance outfit)

Do you use a flat gluing for panel protection ? to avoid any added compression at ribbing time ?

How much reduction along/transverse grain did you see on drying ?




Edited by Olek (06/15/13 12:34 PM)
_________________________
It is critical that you call your Senators and Representatives and ask them to cosponsor S. 2587 and H.R. 5052. Getting your legislators to cosponsor these bills


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#2102937 - 06/15/13 02:47 PM Re: Does a soundboard improve with aging? [Re: tdv]
Ed McMorrow, RPT Offline
2000 Post Club Member

Registered: 12/09/12
Posts: 2348
Loc: Seattle, WA USA
Crown is an "expansion joint" of sorts for the soundboard panel. It allows the board to shrink in dry conditions without pulling apart and also produces a desirable state of relations regarding the impedance of the string board structure.

The compression set that damages the board usually occurs at edge glue joints where two boards with less than perfectly quarter-sawn wood are located. If the board contains perfectly quartered boards-it will resist crushing damage quite well when exposed to high humidity.

I have found that the condition of the bridge caps is far more significant to the reduced treble tone in old bellies than the old panel wood. The panel condition is important-but not quite as the bridge.
_________________________
In a seemingly infinite universe-infinite human creativity is-seemingly possible

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#2102952 - 06/15/13 03:17 PM Re: Does a soundboard improve with aging? [Re: Olek]
Craig Hair Offline
Full Member

Registered: 06/03/11
Posts: 205
Loc: Holyoke, MA
Hi, Isaac,
How much reduction? Along the grain, we see no real change. the long boards still fit tight between the corners. Across the grain, on the longest ribs, the panel can shrink by as much as 20mm. This width is recovered by the insertion of at least two strips of new old wood either side of the bridges. After that we see about a 7 mm reduction in width when the panel is heated for pressing.

We use a curved caul deck. The longest caul has a dish of about 14mm. We may be mistaken, but we have always tried to get the panel to lay as flat as we could so that when it is layed in the cradle the cells on the concave side would be compressed just a little more before the cells on the underside of the rib, stretched from being bent into the curve, are welded by the glue joint. We have always tried to promote compression.

I,m not sure if I,m answering your question, but I have never had much luck adding any new additional bearing to an already fatigued board. It seems to me that at some point in the loss of a board's crown, there comes a point where the board has a tendancy to pull at the rim rather than push. This is a non-dynamic action. energy is consumed by the rim rather than reflected. Adding extra bearing can only immobillize the board further. At least that's how I've made sense of it.
_________________________
Craig Hair
Hampshire Piano
Holyoke, MA

hampshirepiano.co
soundboardrecrown.com

If I seem slow, I simply must be stopped

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#2102970 - 06/15/13 04:08 PM Re: Does a soundboard improve with aging? [Re: Craig Hair]
Olek Offline
7000 Post Club Member

Registered: 03/14/08
Posts: 7904
Loc: France
Originally Posted By: Craig Hair
Hi, Isaac,
How much reduction? Along the grain, we see no real change. the long boards still fit tight between the corners. Across the grain, on the longest ribs, the panel can shrink by as much as 20mm. This width is recovered by the insertion of at least two strips of new old wood either side of the bridges. After that we see about a 7 mm reduction in width when the panel is heated for pressing.

We use a curved caul deck. The longest caul has a dish of about 14mm. We may be mistaken, but we have always tried to get the panel to lay as flat as we could so that when it is layed in the cradle the cells on the concave side would be compressed just a little more before the cells on the underside of the rib, stretched from being bent into the curve, are welded by the glue joint. We have always tried to promote compression.

I,m not sure if I,m answering your question, but I have never had much luck adding any new additional bearing to an already fatigued board. It seems to me that at some point in the loss of a board's crown, there comes a point where the board has a tendancy to pull at the rim rather than push. This is a non-dynamic action. energy is consumed by the rim rather than reflected. Adding extra bearing can only immobillize the board further. At least that's how I've made sense of it.



Thanks Craig

14 mm sound really enormous to me, (have read about 8 mm something). 20 mm for I suppose 1200 mm lenght+- also seem to be more than expected.
But my main question was more about how much panel dimension change do you obtain with low moisture level ?

I just noticed that some astute angle management (computed in % if I get the point) can be done with the bridge, as this one Will tilt somewhat (about 1-2°) so the bridge top is planed with a slant including the tilt so to obtain the final expected geometry on the top of the bridge.

So all this can be computed somehow.

I see what you mean with soundboard "pulling" on the rim, could it be because of wood dimensional change ?

About retractation, there is a web site (on woodworking) where you can enter the species and the different moisture levels (of air, of wood) for a given lenght. The dimensional change is then computed when a second set of variables is entered.
That could allow you on your next project, to document the amount of "life" yet present in the wood.
http://www.woodworkerssource.com/movement.php

5 I did not read well, you get 7 mm less for 1200 mm ? seem to be more than with new spruce ! or you get to a really low EMC, coming from a 14% original level ? that match new wood in that case (that was the question)

AN idea could also use a system that allow to reglue the front of the board a little farther, adding tension thru the bridge, in longitudinal direction (Bluethner really is against any spherical shape on soundboards, due to too much effort at the bridge, but this method is used by some other brand (s?) as "tone amelioration by stress".

PS, expecting a 4 mm crown at the higher spot, with around 40% loss out of the cauls, you see why I find your caul a tad strong. But it may be a compression method (it is, probably) I just seem to read that using so large crown implie an even higher degree of panel drying than with the "flat ribs curved caul" method. May ask more on the ribs than on the panel, is not it ?.

I would be really curious to hear some of your rebuild boards, whenever possible.

The lateral shim tip, was given to me long time ago. 5I heard also the result, some pianos are relatively accessible to that process) Did not have the opportunity to use it or not the courage. May certainly apply well to the break region (but I am unsure the bass end is not stiffened too much).

Best regards






Edited by Olek (06/15/13 04:34 PM)
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It is critical that you call your Senators and Representatives and ask them to cosponsor S. 2587 and H.R. 5052. Getting your legislators to cosponsor these bills


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#2102974 - 06/15/13 04:22 PM Re: Does a soundboard improve with aging? [Re: Olek]
phacke Offline

Gold Supporter until November 11 2014


Registered: 10/18/12
Posts: 578
Loc: CO, USA
Originally Posted By: Olek


...So all this can be computed somehow...



I will put this on my to do list, unless someone has already done it or beats me to it.

Best regards-
_________________________
phacke

Steinway YM (1933)
...Working on:
J. S. Bach, Sonata No. 1 in B minor (BWV 1014) duet with violin
F. Chopin, Prelude 28 (15)

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#2102980 - 06/15/13 04:40 PM Re: Does a soundboard improve with aging? [Re: tdv]
Gene Nelson Offline
1000 Post Club Member

Registered: 09/10/04
Posts: 1530
Loc: Old Hangtown California
Enter the radius crowned soundboard:
Glue up to ribs around 6 to 6.5% moisture content so there is very little compression in the panel. No need to dry the panel down to 4% or less then subject the panel to excessive tension and compression.
Ribs are cut so that the apex of the crown is mostly directly under the bridge except in the lowest bass and treble, where on compression panels the crown happens somewhere on the board and you live with it.
The amount of crown is designed into the radius that is cut onto the ribs and graduates smoothly and evenly across the entire panel. (I like to believe that this makes setting bearing and bridge carving a bit easier)
The ribs are designed to support string down bearing (as a structural member) and they do not resist crown as in a compression board with flat ribs.
String down bearing can be designed so that it is never greater than the amount of available crown.
It is a controllable system with some aspects that are predictable.

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#2102988 - 06/15/13 05:00 PM Re: Does a soundboard improve with aging? [Re: tdv]
Olek Offline
7000 Post Club Member

Registered: 03/14/08
Posts: 7904
Loc: France
Thanks Gene, you added one of the methods.

AS I have seen it pictured the ribs are shaped and can be shaped so the apex is on the 1/3 of the front rail so the bridge is also providing some stiffening and the amount of stress provided to the board is progressly higher when coming to the treble.

That seem to induce much computation to design the ribs and the cauls.

That method put the higher spot of the bridge on the front of the bridge in the 5-6 octave region.

About your drying level, really compression is said to help the panel accept high level of dryness later. and is not necessarily used on flat ribs.

Now probably the more desequilibrium can be entered (within limits) in the panel, the more reactive it must be, (but also the more stress, the best the treble crispness, unless the piano is relatively small)

The amount of control on shape and resiliency is just amazing when you see it.

Then , all computations are said to give results at 20% approx.

DO you use a caul with extra curve or just fitting the final shape , with the method you describe ?

That thread is interesting wink

The descriptions given state about the 4 methods - 2 with more control on final shape - 2 with more resistance to cracks. (to simplify)

Best regards


Edited by Olek (06/15/13 05:02 PM)
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It is critical that you call your Senators and Representatives and ask them to cosponsor S. 2587 and H.R. 5052. Getting your legislators to cosponsor these bills


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#2102994 - 06/15/13 05:25 PM Re: Does a soundboard improve with aging? [Re: Olek]
Craig Hair Offline
Full Member

Registered: 06/03/11
Posts: 205
Loc: Holyoke, MA
14mm may be a measuring error, but not by too much. We do tend to bend a rib to test its tolerance. and this is the longest rib of a yacht tail 109-c chickering at 1280mm.

A 1200mm wide section will shrink between 6 and 8 mm when dried.

the 20mm measurement was the difference between the original size of the panel and its stable adjusted size after all accumulated shrinkage is released through the ungluing.
_________________________
Craig Hair
Hampshire Piano
Holyoke, MA

hampshirepiano.co
soundboardrecrown.com

If I seem slow, I simply must be stopped

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#2103024 - 06/15/13 07:08 PM Re: Does a soundboard improve with aging? [Re: tdv]
Gene Nelson Offline
1000 Post Club Member

Registered: 09/10/04
Posts: 1530
Loc: Old Hangtown California
That seem to induce much computation to design the ribs and the cauls.
_________________________________________________________________________________________________________________
The actual calculations take less than an hour using spreadsheet.
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#2103146 - 06/16/13 01:51 AM Re: Does a soundboard improve with aging? [Re: tdv]
Olek Offline
7000 Post Club Member

Registered: 03/14/08
Posts: 7904
Loc: France
I can imagine that the usual method to compute ribs for an existing panel shape is not that complicated. I talk of something that push the resonant frequencies of the soprano enough on inner stress basis.

The web numbers that are produced could certainly be with a good spreadsheet, but due to the progressive curves the spreadsheet may not be that easy to setup. 4 different radii for each rib seem to complicate the computation enough wink.

Last new board I tuned had a basic and limited treble with no elegance, like with feet in the mud... (on a Steinway) Basses and mediums are easy probably and may be high treble as well, but on the 5th rib region seem to occur a hit or miss game.


Edited by Olek (06/16/13 05:04 AM)
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#2103175 - 06/16/13 03:58 AM Re: Does a soundboard improve with aging? [Re: Craig Hair]
Olek Offline
7000 Post Club Member

Registered: 03/14/08
Posts: 7904
Loc: France
Originally Posted By: Craig Hair
14mm may be a measuring error, but not by too much. We do tend to bend a rib to test its tolerance. and this is the longest rib of a yacht tail 109-c chickering at 1280mm.

A 1200mm wide section will shrink between 6 and 8 mm when dried.

the 20mm measurement was the difference between the original size of the panel and its stable adjusted size after all accumulated shrinkage is released through the ungluing.


20 mm , once the ribs are unglued ! I have seen some horror movies that where less bad !!
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#2103179 - 06/16/13 04:16 AM Re: Does a soundboard improve with aging? [Re: jim ialeggio]
Olek Offline
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Registered: 03/14/08
Posts: 7904
Loc: France
Originally Posted By: jim ialeggio
Originally Posted By: Olek
I am sorry Jim but your logic does not seem to be correct. When the wood take moisture it release from compression, on the glued part.

If a panel that is too much dried suffers, it is not of too much compression.

I disagree Isaac,

The board does not return to its previous state when ambient moisture is re-introduced. The ribs, which are glued across the grain, restrain the panel's return to its previous free state. So as the panel picks up ambient moisture, it expands. However, the expansion is resisted by the ribbing.

This resistance of the ribbing, combined with EMC induced expansion forces the panel into an unbalanced state of compression. It is unbalanced because the un-ribbed side of the panel is unequally restrained, forcing the panel into a crown.

Then, that unbalanced crown is forced into further compression by applying anywhere from 500lbs to over 1000lbs of downbearing.

Jim Ialeggio


Could someone explain that to me ?
As I see it, the underside of the panel is compressed (tensed) at the time of ribbing, if curved cauls are used on a yet dryed panel.

Then when moisture get back, it is retained from expanding but not compressed more (there is indeed some form of compression due to the fact that the wood is not allowed to get to its previous condition, but the drying is there to protect it somehow, giving the wood some resiliency "reserve".

It is said that a lightly dried panel is more prone to develop cracks .

Why wanting to leave the board in an uncompressed condition ?

DO have it right ?

Is the "position" of the neutral fiber in the panel computed, or envisaged, or is it too idealistic to try to get it under control ?
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#2103356 - 06/16/13 02:05 PM Re: Does a soundboard improve with aging? [Re: tdv]
lluiscl Offline
Full Member

Registered: 07/10/06
Posts: 146

A Steingraeber from 1909, with unusual SB grain almost parallel to belly rail... with very long and high ribs disposed longitudinally to the piano length... The panel has less than 7mm thick, has not cracks and perfect downbearing from beginning... I am asking if this way provides more rigidity to the system, at cost to the final sound... (pending to finishing and hearing it).

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#2103375 - 06/16/13 03:02 PM Re: Does a soundboard improve with aging? [Re: tdv]
Gene Nelson Offline
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Registered: 09/10/04
Posts: 1530
Loc: Old Hangtown California

My guess is that the bass and lo-tenor sections are a bit too stiff making it difficult to get a clear defined tone with good fundamental and the treble may not be stiff enough.
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#2103682 - 06/17/13 05:15 AM Re: Does a soundboard improve with aging? [Re: tdv]
Olek Offline
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Registered: 03/14/08
Posts: 7904
Loc: France
Soft tone, with no much high frequencies for the ones I have seen.

But they had many cracks, always
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#2103704 - 06/17/13 07:00 AM Re: Does a soundboard improve with aging? [Re: Olek]
lluiscl Offline
Full Member

Registered: 07/10/06
Posts: 146
Originally Posted By: Olek
Soft tone, with no much high frequencies for the ones I have seen.

But they had many cracks, always


Hi Isaac. According Steingraeber this pictured model is the improved version (30 years later) of the famous last piano Liszt. There are many recordings of this grand (which of course was full restored but maintaining original SB), for instance http://www.youtube.com/watch?v=UV1lmRb4_Gs
It doesn't seem to me precisely a soft tone.

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#2103710 - 06/17/13 07:21 AM Re: Does a soundboard improve with aging? [Re: tdv]
Olek Offline
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Registered: 03/14/08
Posts: 7904
Loc: France
Hello, thank you so much for the recording.
I recognize the characteristic by a relatively fast absorption of energy with no much high partials provided.


Seem to me the panel is not resilient much.
I have a vertical piano with similar setup, and similar round tone but with limited dynamics .

It may be what was called "light panel" construction, while more actual ones range from 6-7 to 9-10 mm.


Edited by Olek (06/17/13 07:49 AM)
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#2103721 - 06/17/13 07:59 AM Re: Does a soundboard improve with aging? [Re: Olek]
lluiscl Offline
Full Member

Registered: 07/10/06
Posts: 146
Originally Posted By: Olek
Hello, thank you so much for the recording.
I recognize the characteristic by a relatively fast absorption of energy with no much high partials provided.


Seem to me the panel is not resilient much.
I have a vertical piano with similar setup, and similar round tone but with limited dynamics .

It may be what was called "light panel" construction, while more actual ones range from 6-7 to 9-10 mm.


Well, personally never heard a 130 years old modest (200 cms) grand piano with this full/complex tone and this great dynamics.
Steingraeber did the things well...

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#2104187 - 06/18/13 02:27 AM Re: Does a soundboard improve with aging? [Re: tdv]
Olek Offline
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Registered: 03/14/08
Posts: 7904
Loc: France
Yes it is juicy, (200 cm is yet full scale or near, BTW).

What I hear is the tone circulation is not very long.

The piano do not saturate easily, on the other hand.

I like that sort of tone, my comments was about real thickness and dynamic plague if compared with more massive/resilient soundboard.
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#2104188 - 06/18/13 02:28 AM Re: Does a soundboard improve with aging? [Re: Olek]
phacke Offline

Gold Supporter until November 11 2014


Registered: 10/18/12
Posts: 578
Loc: CO, USA
Originally Posted By: Olek
Originally Posted By: Craig Hair
14mm may be a measuring error, but not by too much. We do tend to bend a rib to test its tolerance. and this is the longest rib of a yacht tail 109-c chickering at 1280mm.

A 1200mm wide section will shrink between 6 and 8 mm when dried.

the 20mm measurement was the difference between the original size of the panel and its stable adjusted size after all accumulated shrinkage is released through the ungluing.


20 mm , once the ribs are unglued ! I have seen some horror movies that where less bad !!


Great way to state it, Mr. Oleg.

After looking at the numbers thought, I am in full agreement. There is absolutely huge in-plane compressive stress in the soundboard as it wants to expand with humidity when constrained by the ribs and the rim. It is easy to see that Mr. Ialeggio is correct about the frequent existence of yielded wood in the soundboard.

Maybe the following that I am seeing is obvious to some and not to others --
Both modulus of elasticity and yield stress in compression varies with orientation of the grain. For both these figures, the difference is almost an order of magnitude as you move from radial (quarter) sawn to the situation with the grain running in plane with the width of the board (laterally). Expansion with humidity also varies with direction of grain. So, the angle of the grain in the soundboard would make a huge difference in the final mechanical properties of the board. Fortunately, the data for all this seems to exist for Sitka spruce, though there is variability in the figures among the references - makes sense, it is a natural material.

I'm supposing Mr. McMorrow is correct, that some of the stress in the board coming from humidity has to be relieved in bowing in the board (the stress levels would certainly be worst than a horror movie, without something giving). We all know the board gives to an extent, but it would be interesting to quantify this effect.

That is where I am at in my discovery. I will look further and report, but no promises for timeline.

Regards -



Edited by phacke (06/18/13 02:35 AM)
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F. Chopin, Prelude 28 (15)

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#2104192 - 06/18/13 02:40 AM Re: Does a soundboard improve with aging? [Re: tdv]
Olek Offline
7000 Post Club Member

Registered: 03/14/08
Posts: 7904
Loc: France
Boards are clearly "supposed" to be made from quarter sawn.

hey probably are not depending of the quality...

The amount of compression installed at ribbing is what allow the board to accept future humidity fluctuations.
It is supposed to stay within limits of acceptability, a less dried panel would develop ridges (often seen on modern pianos and absent from older ones)


Edited by Olek (06/18/13 02:40 AM)
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#2104235 - 06/18/13 07:18 AM Re: Does a soundboard improve with aging? [Re: Olek]
jim ialeggio Offline
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Registered: 06/03/05
Posts: 731
Loc: shirley, MA
Originally Posted By: Olek
a less dried panel would develop ridges (often seen on modern pianos and absent from older ones)

This is backwards. smile It is the boards that are dried to the edge cell damage that will be pushed over that damage threshold during moisture cycling. Compression ridges do not occur on boards installed at 5.5% or higher. These higher-emc-at-ribbing boards are far enough away from the compression failure threshold that there is more resilience in both the joint and in the wood throughout the field.

Jim Ialeggio
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#2104237 - 06/18/13 07:29 AM Re: Does a soundboard improve with aging? [Re: tdv]
Olek Offline
7000 Post Club Member

Registered: 03/14/08
Posts: 7904
Loc: France
Well I did not make panels, so I have to trust you but if the wood is constrained at ribbing time it will be happy to receive some moisture, and the compression will be less strong than when it is dry.

The ridges I notice on some modern panels at joints are not there on old boards.
It seem evident that the wood have been pushing where no contraction reserve exists and a ridge develop.

I did not notice them on old soundboards (the panel surface is flat without those hops)

Certainly a wood with damaged cells will not keep enough elasticity to follow when the moisture is high, it may happen, but at last it is less sensitive to high level of dryness.

The goal clearly stated anyway is to have a soundboard that contains enough inner stress to accept moisture fluctuations without cracks. "the board is kept in is constrained state for the time of its useful life" (Bluethner, Fenner, U.Laible).

Now I understand that under heavy climatic conditions, the soundboard builder will err on the side of caution, and will make panels that are made more neutral ? Then I was surprised to read that the protective effect against cracks is due to the compression/drying, but I did not invent it.

If not for that, just to raise the treble frequencies, so the treble part of the piano have that shiny quality, and not that tendency to produce more low pitched treble I seem to notice on a few boards I heard.
(together with a "slow" reaction time, seem to me.)

Now I suppose there is the panel of the piano technician, and the one that can be made in a factory with adequate control on drying of all elements (while this does not seem to be so complicated to attain for the equiped tech, while precise wood moisture room may mean a strong deshumidifier, if not heated box.

The ribs seem to be dried more than the panel , the bridge also is dried.

Now I have seen a pneumatic press used with some sort of moistening of the surface of the panel (unless it was a product intended to harden the wood surface before the lacquering) . and I have no real explanation on that, possibly only for the bridge gluing with a certain method.







Edited by Olek (06/18/13 07:43 AM)
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#2104694 - 06/19/13 12:54 AM Re: Does a soundboard improve with aging? [Re: Olek]
phacke Offline

Gold Supporter until November 11 2014


Registered: 10/18/12
Posts: 578
Loc: CO, USA
Originally Posted By: Olek
Boards are clearly "supposed" to be made from quarter sawn.

hey probably are not depending of the quality...


Hello soundboard makers,

What kind of angles (typical and maximum) in the grain are you seeking when you take apart an old soundboard and look at the individual board at the end grain at the board end? How true to quarter-sawn wood are other people using in medium to high quality boards? (I don't ask about you, because of course you are top class, a special case!)

As a coordinate system, assume 0° is approximately ideal quarter sawn wood, like in the blue box here:
http://upload.wikimedia.org/wikipedia/commons/4/45/Softwood_endgrain_marked.png

With this, I would like to make a spreadsheet for the stress state in the board and how it varies with subsequent humidity changes.

Kind regard-


Edited by phacke (06/19/13 02:38 AM)
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Steinway YM (1933)
...Working on:
J. S. Bach, Sonata No. 1 in B minor (BWV 1014) duet with violin
F. Chopin, Prelude 28 (15)

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