The point i was making is NO sample method is an indicator of what the panel is doing.
I use to love making widgets and had about twenty of them, all would react differently with the change of seasons. The Nossaman gauge is just another(even less accurate) widget. So the idea followed to not use a widget at all, but get direct readings from the actual panel, First i went with weighing each panel as water was removed. But, my experiments show that the weight reduction is not an accurate indicator of shrinkage. Now i use a Soundboard ruler. Its a special ruler i made to measure shrinkage before and after the bridge is glued on if i wish..
The panels i mentioned earlier were only 2 hours in the process, and were already going at different trajectories. It should have been identical. Now on the second day, the shrinkage so far is just passing 10mm down from 910mm
Original Message:
Sent: 09-12-2021 16:18
From: Alexander Brusilovsky
Subject: Rib Stock
Keep cut off piece of the panel together with rest of the panel and monitor it weight . Changing of the weigh indicates amount of lost or added amount of water, that can be easily transposed into relative humidity.To find weight under 0% relative humidity put the piece into kitchen oven 300F until weight stops to change.
Alexander Brusilovsky
Original Message:
Sent: 9/11/2021 10:08:00 PM
From: David Love
Subject: RE: Rib Stock
There are different ways to get the job done.
However, the one that shrunk to 908mm changed .2%, the one that shrunk to 907 changed .3%. Is that significant? Longitudinal (with the grain) change is typically .1% - .2%, generally considered not significant. Across the grain shrinkage is typically on the order of 5-6% but varies from species to species and also between flat sawn and quarter sawn (quarter sawn shrinks less as do soft woods compared to hardwoods). We don't know the starting point of either panel but generally 2 hours in the hot box I would not consider enough time to determine anything and the percentage of shrinkage would indicate that you didn't dry them long enough to be able to really determine anything meaningful. The small difference might reflect the initial rate of change not necessarily the ultimate change. Given adequate time they may very well end up the same, or closer anyway.
For further reading there are many articles and books available. Here's one.
https://www.wood-database.com/wood-articles/dimensional-shrinkage/
------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
Original Message:
Sent: 09-11-2021 14:06
From: Chris Chernobieff
Subject: Rib Stock
Just to follow up.
I put two soundboard panels in the oven today. Both identical in size for 2 large uprights. Then as i always do, made my 910mm marks (which uses the panel itself as a humidity gauge) on each.
I pulled them both out of the oven 2 hours later. One shrunk to 908mm, the other to 907mm.
So there's variability already. It does appear that one has slightly tighter grain than the other.
-chris
------------------------------
Chernobieff Piano Restorations
"Where Tone is Key"
chernobieffpiano.com
grandpianoman@protonmail.com
Lenoir City, TN
865-986-7720
Original Message:
Sent: 09-10-2021 18:04
From: David Love
Subject: Rib Stock
I completely disagree, sorry Chernobieff. Of course it only measures the change in the gauge. But it's measuring the change in a piece of spruce same thickness as the panel. If the gauge sample
is changing it's a safe assumption that the panel is too. It has worked very effectively for me though my current method doesn't much rely on it anymore. I dry the panel down, glue on every other rib and then the assembly goes back in the box until it's ready for the rest of the ribs. Never had a board fail to crown.
------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
Original Message:
Sent: 09-10-2021 14:23
From: Chris Chernobieff
Subject: Rib Stock
Love says,
"I don't use the Nossaman gauge as an indicator of what the EMC is, I use it as an indicator of change happening in the panel. That's all that is necessary."
And it doesn't even do that. It is only measuring the change in the gauge only. That's the flaw in any sample method.
If you just want to measure movement, then simply putting two index marks directly on the panel can do that, and it'll be the actual movement of the panel.
I measure the board itself throughout the making process and set my kiln to the desired EMC environment. When the weight of the board stabilizes, its good to go. Usually takes just two days - 3 days. Since i am tweaking the process at the moment, i am using 3 boards at a time as controls and data comparison. But since i started measuring the boards weight as a means of emc control, its quickly become apparent to me how accurate and sensitive this method is. So a control won't even be necessary in the future.
-chris
------------------------------
Chernobieff Piano Restorations
"Where Tone is Key"
chernobieffpiano.com
grandpianoman@protonmail.com
Lenoir City, TN
865-986-7720
Original Message:
Sent: 09-10-2021 13:19
From: David Love
Subject: Rib Stock
One other variable I notice that I didn't mention and may well affect compression crowned boards is whether the inner rim is flat or sloped. Many are flat and I always make sure to chamfer the inner rim so that it slopes as closely as possible to the crown of the ribbed board. It's a subtle thing but may have an impact on the residual crown when compared to a flat inner rim in which the pa el is forced down to contact the inner edge of the inner rim. BTW I do dry down the panel again before gluing it into the piano.
In short, there are so many small things that can add up to different outcomes it's hard to blame it on any one thing but, again, I think controlling EMC is probably one of the easier things.
------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
Original Message:
Sent: 09-10-2021 10:19
From: David Love
Subject: Rib Stock
I don't use the Nossaman gauge as an indicator of what the EMC is, I use it as an indicator of change happening in the panel. That's all that is necessary.
I rib at 5% EMC (6-6.5% is too high for me but I don't do pure rib crowned and supported structures, I want more compression, somewhat less reliance on the rib scale, than that offers). So the panel (and the ribs) go into the hot box controlled for corresponding RH for a period of time sufficient to insure that the panel is stable at that EMC. The gauge goes with it. When it comes out, the gauge is tarred (set to zero) and watched for any change. At any hint of change on the gauge during ribbing the board goes back in the box.
By "ridiculously low levels" I assume you mean the reported NY Steinway 3.5% EMC. I don't know if that's accurate or not but most of the people I know making soundboards are ribbing at around 5%+/-. Hamburg Steinway uses crowned (not flat) ribs and may not rib at the same low EMC as NY but I'm not privy to that information either other than what I hear.
It appears that the more you rely on compression for crowning, the less reliable the results are. But I don't think that's because of lack of control of the EMC. Rather, I think that represents variations in across the grain resistance to deformation (crushing) and perhaps different expansion rates, or both, that occur between different panels. While that will always be a factor it appears to be less of one in panels that rely less on compression for crown formation and shift some of that to a curved, rather than flat, rib.
There are also just inherent differences in tone between different panels even of the same species. That's pretty apparent when you talk to luthiers who employ tap tests with apparent predictability to determine differences between, say, guitar tops.
Even with the strictest controls in place there will always be differences in tonal outcomes due to inherent differences in natural materials. The only way to avoid that is to go to synthetic materials, carbon fiber, or something like that. In the meantime we do have a system for tweaking downbearing that does seem effective in charging impedance on light structures that rely, at least some, on compression for crown formation. In my experience, it is less effective on rib crowned and supported structures that tend to have heavier rib scales with smaller radii on which crown formation is purely a function of the rib radii. I have no comment as to why that would be.
------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
Original Message:
Sent: 09-10-2021 08:45
From: Jim Ialeggio
Subject: Rib Stock
<Ron Nossaman made me a very clever EMC gauge some years ago which I still use that is a very reliable indicator of changing EMC.
Its only reliable, or rather apparently reliable if you have never checked its readings against a lab setup oven dry as an control. Owing to the hysteresis effect, where stock never returns to its original dimension, owing to temperature effecting the dial indicator internal dimension mechanism, attachments to the wood structure, etc, etc, the readout, having been tested in my shop, against oven dry samples, repeatedly, is unreliable. Further, having put two together in Jude's hotbox, his and mine, they also disagreed to a degree that was quite surprising. I have made two of these, the second trying to overcome internal dimensional inaccuracies. I trust neither of them, other than to give me a very vague idea that changes may be occurring.
<But I think controlling EMC is the least of our concerns if you pay attention to it.
Agree, but only if you are not drying down to the ridiculous levels some builders and high end manufacturers claim. I don't think anyone in this discussion is drying to ridiculous levels, but it is done, and claimed, and produces highly inconsistent results.
<I agree fully. IMHO, if you can't control EMC and be sure of it, maybe you just don't have the knowledge and/or equipment/facilities needed to be doing that level of work.
Only maybe, as I have seen boards develop performance challenging cracks in less than a one year cycle, even from participants in this discussion...and have experienced it once myself. Its similar to the experience of 30 yr seasoned pro's I talked to, when writing my tuning pin torque article. One said, and I quote, "What a loser! You'd think, after 30 years, I could learn how to drill a freak'in hole". Its only easy if you have not tested your results against a reliable control. Internal hot box temp and humidistats, ones that function without readout degradation at elecated temps, cost $1500.
The system is more complicated than this one parameter, for sure, thinning being one of the most destructive and problematic. But the point I am making, is that one must accept unknowns in the fabrication process, even with high skill levels, and excellent equipment capabilities. Because of these unknowns, it makes major sense, to me, to spend serious time learning to adjust the as-built system, before the strings go on, and after.
------------------------------
Jim Ialeggio
grandpianosolutions.com
Shirley, MA
978 425-9026
Original Message:
Sent: 09-10-2021 05:57
From: Terrence Farrell
Subject: Rib Stock
David L. wrote: "If you're ribbing boards in Florida it's a bit trickier."
Actually, that's only if you are ribbing the panel outside in the summer time. In that case, you'd really have to be a magician! When I rib a board in in the summer in my shop here in the REAL Bay Area, first of all I do it in my shop with closed doors and windows, then I run the AC for a good while and then turn the dehumidifier on. Those efforts will keep the temperature around 70 - 75 F, and the RH down to about 35%. That is good for an easy 7% EMC. I usually dry my panels to 6 - 6.5% EMC for ribbing, so the small difference in environment between the shop and the hot box doesn't seem to be a problem. And of course, in the winter, as long as we're not in the midst of a rare week long rainy spell, it is very easy to meet target conditions in the shop. And even if there is the rare rainy spell, all I need to do is crank up the dehumidifier for a day or two. Even without the dehumidifier or the AC, winter or summer, my shop really never gets above 60% RH. All I need to do is run the AC in the summer once in a while and I'm down closer to 50% RH.
------------------------------
Terry Farrell
Farrell Piano Service, Inc.
Brandon, Florida
terry@farrellpiano.com
813-684-3505
Original Message:
Sent: 09-10-2021 00:55
From: David Love
Subject: Rib Stock
I think different outcomes with compression crowned boards has more to do with differences in the particular piece of wood than the ability to control EMC which really isn't that difficult. It's easy to control a hot box environment and time required to stabilize the wood at a particular EMC depending on the panel thickness is a known quantity. Whether Steinway was consistent or not doesn't mean it's not possible to be consistent especially for the one-at-a-time small shop. Working time once out of the box depends on the ambient conditions, of course, and many people don't rib boards in high humidity conditions for that reason. But to suggest that it's just a crapshoot or not controllable I don't think is correct.
Impedance levels can be controlled to some degree with changes in bearing made easier by adjustable perimeter bolts and adjustable nose bolts. You won't salvage a board that doesn't crown for some reason with changes in bearing but small tweaks can be made and are done routinely by some of the top manufacturers.
Ron Nossaman made me a very clever EMC gauge some years ago which I still use that is a very reliable indicator of changing EMC. There's discussion of it in the archives I'm sure but it consists of a smallish piece of spruce connected to a dial gauge that shows any change in expansion or contraction in or out of the hot box. It simply follows the panel around when you are working on it. Using pneumatic presses it takes very little time to glue up half the ribs before the dial shows any change and then the panel goes back in the box until it's ready again for the remaining ribs. Of course if you are ribbing boards in Arizona where the ambient humidity often correlates to the target EMC it's not a problem. If you're ribbing boards in Florida it's a bit trickier.
------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
Original Message:
Sent: 09-09-2021 15:13
From: Jim Ialeggio
Subject: Rib Stock
It all argues for protocols that allow one to adjust the "as-built" board system. The fact that we don't prioritize after-the-fact adjustability of the board system, is somewhat mind boggling, if you ask me. We have after-the-fact impedance adjustments in hammer voicing, but they only get one so far, when the problem is not exclusively the hammer's problem.
------------------------------
Jim Ialeggio
grandpianosolutions.com
Shirley, MA
978 425-9026
Original Message:
Sent: 09-09-2021 12:42
From: Terrence Farrell
Subject: Rib Stock
Jim I. wrote: "How can you have a control, when the control, even out of the hot box, is constantly changing, depending on the ambient conditions."
IMHO, that is why controlling soundboard building environmental conditions - even when you can do that real well - still leads to inconsistencies in soundboard performance and longevity. Every piece of spruce is going to have different grain (annular ring) densities AND different ratios of winter wood (very dense) to spring/summer wood (much less dense). Many folks think that low grain density equals low wood density and tight grain means higher density. That may often be true, but I've seen lots of Sitka that had very high grain density that was still very low density wood because the winter wood to summer wood was very low.
------------------------------
Terry Farrell
Farrell Piano Service, Inc.
Brandon, Florida
terry@farrellpiano.com
813-684-3505
Original Message:
Sent: 09-09-2021 08:44
From: Jim Ialeggio
Subject: Rib Stock
could you clarify your procedure for reading emc? Its not clear to me what you are doing. How can you have a control, when the control, even out of the hot box, is constantly changing, depending on the ambient conditions. Could you describe your process in detail?
This all speaks volumes at to why compression boards like Steinway's are so inconsistent. Knowing exactly what the moisture content of a board is, is not possible with the precision compression crowning requires. That begs a whole different subject, which I have been R&D'ing for several years, which is developing ways to "adjust" the board stiffness profile, selectively, after ribbing and after glue in to the rim. But, it still remains an incredibly mobile target.
------------------------------
Jim Ialeggio
grandpianosolutions.com
Shirley, MA
978 425-9026
Original Message:
Sent: 09-08-2021 23:06
From: Chris Chernobieff
Subject: Rib Stock
Oven drying is not accurate at all because the behavior of a small piece is different than a large piece such as a panel. That is why i abandoned the "Gravagne" widget. I also have to deal with daily changes of humidity levels, and i finally came up with an accurate way, which is to measure water weight in the actual piece and use a secondary board for a control. I check and alter daily the RH% and adjust the heat accordingly. When the weight of the board equalizes you are good to go.
I was thinking of Johns method in general and i have come to the conclusion that it doesn't work. The modern piano soundboard is more or less in a compression state, and johns method puts the soundboard in tension mode. Which is counterproductive for longevity. The new glue joint for a foot long addition just would not contain the added strength that would be desirable. I would think that drying the whole board would be a prerequisite for any chance of this working and filling cracks with new wood in the panel as an "evil" necessity? Some kind of accurate means of measuring the results as time progressed would also be necessary to determine success. Otherwise a new board is still the best way to go.
-chris
------------------------------
Chernobieff Piano Restorations
"Where Tone is Key"
chernobieffpiano.com
grandpianoman@protonmail.com
Lenoir City, TN
865-986-7720
Original Message:
Sent: 09-06-2021 11:44
From: Keith Roberts
Subject: Rib Stock
Some clarification,,, I hope.
The German guy at Kassmans was an aircraft engineer. He designed gliders and such. Weight to him was extremely important. This was when I was working in Erwin's shop so I was interested in other peoples concepts of building a board,
Rib crown,, the German guy didn't like it. He used only very tight straight grain,, I'm not sure the specie. He said cutting the grain as in rib crowning weakens the rib and the size of the rib is bigger. He glued in a dished caul and probably compression crowned to some extent.
Being the engineer type I question sound transmission. The bridge in the piano when it becomes unglued doesn't work well. Sure other instruments use no glue probably for the reason of sound transmission but glue seems to be necessary in a piano,
I view the glue joint as a threshold/ barrier. A hurdle perhaps. The speed that sound travels is different with different mediums. At a glue joint you probably have a reflection as well as absorption.
My thoughts on the different glues. Please add more,,,
Glue that has a heat plasticity would seem to have a deadening effect on sound.
Viscosity and penetration into the wood has effect on the thickness of the glue joint.
Hardness is a factor.
------------------------------
Keith Roberts
owner
Hathaway Pines CA
209-770-4312
Original Message:
Sent: 09-04-2021 17:36
From: David Love
Subject: Rib Stock
Are we really worried about sound transmission through glue joints, especially the glue joint between the rib and the panel or, in this case, the glue joint between the laminates of a rib??? I don't think so. That's not really how soundboards work. Many connectors aren't even glued to the soundboard at all, violins or guitars with drop in saddles for example.
There's no reason you couldn't use a hard wood for the ribs but it might change the voice some. The purpose of ribs is to add structural integrity to the sb and create a balance between flexibility (loudness) and stiffness (sustain), and mass plays a role too but the goal isn't necessarily minimal mass: light but not too light, stiff but not too stiff, as the saying goes.
Spruce has fairly ideal properties for that and many instrument builders use spruce not only for the soundboard but for the ribs (or bracing) as well. Whether you epoxy the ribs or use Titebond or hide glue I don't think matters as long as the glue joint is solid and stable. That being said I don't see much reason to use epoxy except perhaps in this case for its gap filing properties.
Just to add, sitka top guitars often have sitka bracing (the equivalent of the ribs) and some guitars do employ maple braces. The combination of those materials and the design (and a bunch of other stuff) are part of what gives the instrument its voice. Many different materials (that includes glue) are being used for both panels and ribs these days with many different treatments and with somewhat different tonal results. But I don't think the glue has much to do with it.
------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
Original Message:
Sent: 09-04-2021 11:27
From: Keith Roberts
Subject: Rib Stock
If weight don't matter, then why not use hardwood for the ribs?
For the same reason you don't use them as concrete form stakes. I had some old side boards that were oak and I ripped them and put a point on them. They bust into pieces. They are not structural as a floor joist because of the the grain.
Sauter? was into super light boards. Aircraft engineers from what I gather. I talked to the owner/designer at Kassman Piano in Berkeley. In discussing sound transmission through glue joints,, he said using epoxy was like pouring lead into the soundboard.
Then we listened to two different pianist play his piano.
The older jazz guy had problems. He was a dinner show player. The bass would erupt on him with almost a burp when he tried to add a little extra. He had a hard time controlling the volume evenness. Maybe he needed some lead in the board.
The undergraduate kid that played a classical piece,, he hit it hard and aggressive and the piano responded beautifully,,,,
Take your best guess with what you have.
------------------------------
Keith Roberts
owner
Hathaway Pines CA
209-770-4312
Original Message:
Sent: 09-03-2021 22:10
From: Jim Ialeggio
Subject: Rib Stock
Sigh...Chris...and now a word from our sponsor...
If weight don't matter, then why not use hardwood for the ribs?
Likewise since laws don't stop folks from breaking the law, why bother having laws at all? Some folks need to see binary certainty in everything, and others don't. ..however, the pianos all still seem to sound like...uhh...pianos.
------------------------------
Jim Ialeggio
grandpianosolutions.com
Shirley, MA
978 425-9026
Original Message:
Sent: 09-03-2021 19:30
From: David Love
Subject: Rib Stock
Sorry, of course I neglected to mention Terry Ferrell who supplies top quality materials to several high end builders.
------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
Original Message:
Sent: 09-03-2021 10:27
From: Terrence Farrell
Subject: Rib Stock
I hear the Terry Farrell has a ton (or two!) of aged Sitka Spruce in his climate controlled shop and that he'd be happy to slice you off a hunk or trim individual ribs to spec.
------------------------------
Terry Farrell
Farrell Piano Service, Inc.
Brandon, Florida
terry@farrellpiano.com
813-684-3505
Original Message:
Sent: 09-02-2021 10:54
From: John Pope
Subject: Rib Stock
Soundboard builders,
Where do you get your rib stock?
------------------------------
John Pope
University of Kentucky School of Music
Lexington, KY
------------------------------