Dead sounding slab of maple. Should I use it?

[Don Noon]

48 minutes ago, David Burgess said:

Most of the graphs I've seen have the bending strength higher at both 0 and 90 degrees, than in between.

Yes, for varying off-quarter angle.  But Marty's plot is for varying from the longitudinal grain direction to 90 degrees, and you have to guess if the 90 degrees ends up at the radial or the tangential direction.

I would also make a distinction between strength and stiffness, as they aren't interchangeable.

[ernym]

21 hours ago, Dr. Mark said:

The only one I can think of is if you come across some really gorgeous slab wood, but of course there's lots of gorgeous wood around.

This one is going to be an instrument someday...last of my pieces from Whale Bay Woods

 

[David Burgess]

2 hours ago, Don Noon said:

Yes, for varying off-quarter angle.  But Marty's plot is for varying from the longitudinal grain direction to 90 degrees, and you have to guess if the 90 degrees ends up at the radial or the tangential direction.

I would also make a distinction between strength and stiffness, as they aren't interchangeable.

Well, you need to start thinking more like a violinmaker than a rocket scientist.
Yes, the more technically correct word for me to have used would have been "stiffness". Admittedly, a faux pas on my end.

[LCF]

I'm still curious as to how the deadness was assessed. How to hold? how to tap; makes a big difference.

 

Wandering around my woodpile there isn't anything I can lift that I can't get a note out of even a rectangle of 12mm mdf hums quite well. 

[David Beard]

36 minutes ago, LCF said:

I'm still curious as to how the deadness was assessed. How to hold? how to tap; makes a big difference.

 

Wandering around my woodpile there isn't anything I can lift that I can't get a note out of even a rectangle of 12mm mdf hums quite well. 

I don't know about the OP.

If you just lightly scratch your finger nails over pieces of wood, some will report this with very clear crisp sounds reflecting the scratching.  Other pieces of wood will give a more dampened report.

This is a different thing than a billet having particular dimension and properties to produce a pitched natural resonance when you tap.  Such resonances depend on many factors, including size and shape.

 

[LCF]

7 hours ago, David Beard said:

I don't know about the OP.

If you just lightly scratch your finger nails over pieces of wood, some will report this with very clear crisp sounds reflecting the scratching.  Other pieces of wood will give a more dampened report.

This is a different thing than a billet having particular dimension and properties to produce a pitched natural resonance when you tap.  Such resonances depend on many factors, including size and shape.

 

I'm aware of 'scratch mode' but you're suggesting two or more different kinds of damping. I'm not so sure they're unrelated. Bending mode (beam)  resonances can be got from all sorts of shapes and conditions of materials not just from classic marimba bar shapes.  You only have to hold the victim loosely  in just the right spot and tap. Otoh I think Don Noon's style of  damping measurements are from lengthways resonances, compression waves. It would be  straightforward to compare those damping rates with beam mode damping rates. 

[Don Noon]

4 hours ago, LCF said:

Otoh I think Don Noon's style of  damping measurements are from lengthways resonances, compression waves. It would be  straightforward to compare those damping rates with beam mode damping rates. 

No, the compression wave method I only use for speed of sound calculations.  It's fine for frequency, but not clean enough to get a good decay rate reading.  For damping, i use the lowest bending mode frequency... if it's clean.  As I mentioned, somethimes there's a nearby twisting mode frequency which interferes with a clean measurement.  It doesn't ring well, and can sound like a dead slab of wood.  

Whether a dead-ish ring is due to this mode interference or actual high damping, I wouldn't worry too much about it in maple.  The back is far less important than the top regarding what happens in the critical higher frequencies.  My primary reason for avoiding slab-cut wood is that it is significantly more prone to shrinkage and cracking.  If you really want to use it, I think it is important to make sure it is extremely well seasoned... or moderately torrefied.  If you want to get the absolute maximum total sound out of the instrument, I'd still want a quartered back.

[David Beard]

Regardless the hand wringing, history shows countless slab cut fiddles, many favored by top virtuosos.

Even slab cut willow cellos have faired well for centuries.

[JacksonMaberry]

One of the four I'm finishing up right now. Eager to hear them, they're my first time using slab. 

[Don Noon]

2 hours ago, David Beard said:

Regardless the hand wringing, history shows countless slab cut fiddles, many favored by top virtuosos.

Even slab cut willow cellos have faired well for centuries.

I'd like to see some statistics on the % of slab backs that crack, vs. quartered backs.  I know it's only anecdotal, but I recall looking at some old-ish violins in a shop, and thought it was alarming how many of the slab backs had cracks.  Even without seeing that, I can think of no good reason to use a cut that's more questionable physically,.. other than perhaps make a copy of some famous slab-back instrument.  Or if a client has some strange attraction to the look of a slab cut back.  Personally, I'm not a fan of the appearance.

[Spelman]

22 minutes ago, Don Noon said:

I'd like to see some statistics on the % of slab backs that crack, vs. quartered backs.  I know it's only anecdotal, but I recall looking at some old-ish violins in a shop, and thought it was alarming how many of the slab backs had cracks.  Even without seeing that, I can think of no good reason to use a cut that's more questionable physically,.. other than perhaps make a copy of some famous slab-back instrument.  Or if a client has some strange attraction to the look of a slab cut back.  Personally, I'm not a fan of the appearance.

The wood that @ernym posted looked kind of awesome

[ernym]

40 minutes ago, Spelman said:

The wood that @ernym posted looked kind of awesome

I've haven't made any plain slab cut instruments yet. Any that I've seen have been fine but I would rather use quartersawn. This exceptional quilted big leaf I'm willing to use being 18 years dried without issues. And it's too nice not to use!

[Don Noon]

I suppose if I had a great-looking slab back like that one, I might be tempted to use it.  But there are great-looking quartered backs too, and for the previouly mentioned reasons, that's all I'll purchase... unless some client gives me a pile of money upfront to do otherwise .

[LCF]

48 minutes ago, Don Noon said:

I suppose if I had a great-looking slab back like that one, I might be tempted to use it.  But there are great-looking quartered backs too, and for the previouly mentioned reasons, that's all I'll purchase... unless some client gives me a pile of money upfront to do otherwise .

I believe birdseye maple is usually a slab cut. Working that stuff would surely be like a rod for your back. 

[Marty Kasprzyk]

If you are using slab cut wood should the grain lines following the arch shape or cross it.  )) vs. )(

[ernym]

2 hours ago, Marty Kasprzyk said:

If you are using slab cut wood should the grain lines following the arch shape or cross it.  )) vs. )(

I'd like to know too . My slabbed piece has cupped a little in 18 years but no cracks.

So should I carve the arch in the direction of the cup )) 

 

or in the opposite direction )( 

 

 

[Don Noon]

I don't think there can be any certainty about these kinds of details.  The example slab-cut isn't absolutely perfectly on the slab all across the board; there's a skew angle toward the edges.  If you cut the arch to follow the annular rings, that would get the whole plate closer to the slab direction.  The other way, the skew would be stronger in the steeper part of the arch, and thus be somewhat less stiff... recalling that a skew angle of ~45 degrees is about the lowest crossgranin stiffness you can get.

All this theory gets nowhere, really.  The variation in stiffness due to skew cut isn't likely to be much (as opposed to spruce, where the rectangular cells make the off-cut angle quite important).  Good luck trying to guess if these small differences make a sound difference, and I have no clue if skew vs. slab is more or less prone to cracking.

I suppose that having the arching follow the annular rings might give a slightly more uniform look, but again who knows.

[Marty Kasprzyk]

10 hours ago, ernym said:

I'd like to know too . My slabbed piece has cupped a little in 18 years but no cracks.

So should I carve the arch in the direction of the cup )) 

 

or in the opposite direction )( 

 

 

About 20 years ago I made a violin with a Bigleaf maple slab cut one piece back.  It was beautiful wood too and old but I remember that when I was reducing the thickness of the wood it would warp a little each time the thickness was reduced.  I thought that it was relaxing residual internal stresses from the original thick state.   It was not possible to keep the rim always flat.

The final plate was thin enough that it was quite  flexible and I simply clamped and glued the finished warped plate to the rib assembly.  The violin sounded good but that's not important if it looks really great.

[ernym]

Whatever happened to that violin? Did it crack? It sounded good but not great?

I recently had a quartersawn Bosian two piece back warp when I cut through it. That was a surprise.

Would you use this piece of bigleaf?

[Davide Sora]

6 hours ago, ernym said:

I recently had a quartersawn Bosian two piece back warp when I cut through it. That was a surprise.

Due to the release of internal tension every piece of wood warps and moves when you carve it, especially when hollowing out the inside, and to a lesser extent when you carve the arching.  Some pieces more and others less, but they all do it, even if very seasoned, with the tangential cut towards the "more" side. Even a perfect quarter cut is not at all exempt from it.

[Marty Kasprzyk]

7 hours ago, ernym said:

Whatever happened to that violin? Did it crack? It sounded good but not great?

I recently had a quartersawn Bosian two piece back warp when I cut through it. That was a surprise.

Would you use this piece of bigleaf?

I entered into a VSA competition but it didn't win anything.  The tone judges very much liked its sound but the strings were way too low over the fingerboard so they couldn't evaluate it fully--I learned that proper setup was crucial.

The worksmanship judges liked its appearance but scored it poorly as a result of not having a scroll or purfling to gain points with.  

Afterward I donated it to a youth orchestra and haven't seen it since so I don't know how well its helf up.   I had intended to claim a $20,000 charity deduction on my income tax filing but my income then was so low that I just took a standard deduction rather than an itimized one.

I would use your piece of bigleaf but it might be better to listen to others.

 

 

 

[Don Noon]

4 hours ago, Davide Sora said:

Due to the release of internal tension every piece of wood warps and moves when you carve it, especially when hollowing out the inside, and to a lesser extent when you carve the arching.  Some pieces more and others less, but they all do it, even if very seasoned, with the tangential cut towards the "more" side. Even a perfect quarter cut is not at all exempt from it.

Torrefying reduces internal stresses as much as you can get... if it's done carefully.

Of course I had to bring this up.

[David Burgess]

12 hours ago, Davide Sora said:

Due to the release of internal tension every piece of wood warps and moves when you carve it, especially when hollowing out the inside, and to a lesser extent when you carve the arching.  Some pieces more and others less, but they all do it, even if very seasoned, with the tangential cut towards the "more" side. Even a perfect quarter cut is not at all exempt from it.

Agreed.

[Claudio Rampini]

On 7/20/2024 at 5:41 AM, ernym said:

I'd like to know too . My slabbed piece has cupped a little in 18 years but no cracks.

So should I carve the arch in the direction of the cup )) 

 

or in the opposite direction )( 

 

 

In my opinion this is the worst case when we are using a slab cut back because it's far from the tree trunk center, anyway the "cupping" is not that bad. Back to the topic: the slab cut back tone is not dead or "deaf" compared to a radial cut back, it's depending by the dimensions of your wood. But the real question should be ""what's the reason to use a slab cut back?". From the tonal properties view, it can give you a special sweet and mellow tone.

[Marty Kasprzyk]

4 hours ago, Claudio Rampini said:

 But the real question should be ""what's the reason to use a slab cut back?". From the tonal properties view, it can give you a special sweet and mellow tone.

I believe slab cut Bigleaf maple has a very unique and more interesting appearance than if it was quarter cut which looks more like millions or ordinary curly maple backs.