Slab- cut maple

[cornerblockchris]

Hey all,  I have just milled a block of slab -cut maple into a one piece back and 14 rib pieces.  I have never made a violin with slab-cut wood, so I am seeking advise/cautions from those luthiers who have done so.  I know that many early Amati family instruments employed slab-cut wood, so it can't be a complete disaster.  Should I expect to use thicker graduations, are slab cut ribs stable enough as they age, any feedback like that.  I must say that the wood has a wonderful shimmer that should look gorgeous under varnish.  I am using a plainer but quartersawn neck billet.  Thanks for any feedback you can offer.

Edited April 11 by cornerblockchris
misspellings

[Don Noon]

I have never made a violin from slab-cut maple either, nor do I intend to.  It's not as stiff or strong crossgrain,and it's less dimensionally stable with aging and weather.

That said, there are plenty of examples of slab-cut backs that seem to have survived and functioned just fine, so there is a decent chance that you could do the same (I have also seen a few examples with post cracks, which adds to my hesitancy to use slab maple).  Seasoning well I think would be important.

I'd really worry about slab-cut ribs, being so thin and easily damaged, but I suppose you could make them thicker too.  Perhaps some of the more experienced makers and restorers have some real-world experience here.

[Deo Lawson]

The pros use it here and there, to great effect and certain slab grain is absolutely beautiful as well. The typical course of action seems to be leaving it somewhat thicker all over, to make cracks less likely.

 

I am working on my first slab back now as well. I don't know if I'd want to make ribs out of it, feel like that's asking for trouble.

[Anders Buen]

My small experience with slab cut backs are that they appear to give violins with a low frequency B1+ resonance mode. As the hygroscopic shrink and swell directions of maple is larger in the sideways direction of the plane of a slab cut plate (the tangential direction) than the standard, radial direction. Possibly a larger risk for cracks, and a somewhat "softer sound".

[cornerblockchris]

Thanks to everyone who responded to my query about slab-cut wood.  After reflecting on your input, I have decided to change my Maestronet handle to chickenoutchris{:-))  Life is too short to take a gamble when I already have plenty of great quartersawn wood to work with.  I will make a few more violins with safer materials, then one day I will pull this slab-cut stuff out again and.......?

[Altgeiger]

1 hour ago, cornerblockchris said:

pull this slab-cut stuff out again and.......?

... make a viola out of it. (I think they're usually more successful than slab cut violins.)

[martin swan]

So many great 18th century violins made with slab cut wood - but they obviously didn't know what they were doing.

[David Burgess]

54 minutes ago, martin swan said:

So many great 18th century violins made with slab cut wood - but they obviously didn't know what they were doing.

How many of them have had no back cracks? Repairs can take quite a bit out of a musician's budget, and their enjoyment of a fiddle.

I have never made an instrument with a slab back, and likely never will. I was a restorer before I was a maker, and some things I learned from repairing a lot of old instrument have stuck with me.

[Brian in Texas]

52 minutes ago, David Burgess said:

I have never made an instrument with a slab back, and likely never will. I was a restorer before I was a maker, and some things I learned from repairing a lot of old instrument have stuck with me.

So, one piece backs are a no-go? Interesting. Granted I'm a beginner, but I haven't come across this particular stylistic aversion before. I'm guessing in your experience, they're more prone to issues in the long term?

[violinsRus]

10 minutes ago, Brian in Texas said:

So, one piece backs are a no-go?

Yeah, you a beginner, we all were at one point! Burgess doesn't like to use backs cut on the slab, one piece or otherwise. That's how I'm reading it...

[Don Noon]

1 hour ago, violinsRus said:

Burgess doesn't like to use backs cut on the slab, one piece or otherwise. That's how I'm reading it...

It's the same point I made earlier, but with more experience behind it:  slab cut means that the tree's tangential direction is across the width of the back, and that's the wood's weakest direction, i.e. more prone to post cracks among other things.

It CAN work and survive... (Martin Swan's point), but for maximum freedom from potential problems, quartered is better.

[martin swan]

8 hours ago, Don Noon said:

It's the same point I made earlier, but with more experience behind it:  slab cut means that the tree's tangential direction is across the width of the back, and that's the wood's weakest direction, i.e. more prone to post cracks among other things.

It CAN work and survive... (Martin Swan's point), but for maximum freedom from potential problems, quartered is better.

I wonder if it's more critical with flatter arching? I think a higher arch has more ability to absorb dimensional change ...

For myself I haven't really clocked slab cut backs as being more prone to cracking but I have noticed they tend to bulge more around the post.

 

[HoGo]

36 minutes ago, martin swan said:

I wonder if it's more critical with flatter arching? I think a higher arch has more ability to absorb dimensional change ...

Only in central parts but not near blocks I guess.

I have used few slab cut maple one piece and also two piece backs on mandolins and matching ribs and none have reported cracks so far.

Most if not all the birdseye backs or quilt/bubble figure maple are slab cut.

I make sure to glue the backs and tops to ribs under controlled humidity of around 40%. They seem to survive drops below 20% with no problem.

 

[Don Noon]

4 hours ago, martin swan said:

I wonder if it's more critical with flatter arching? I think a higher arch has more ability to absorb dimensional change ...

For myself I haven't really clocked slab cut backs as being more prone to cracking but I have noticed they tend to bulge more around the post.

I don't see arching having much influence on post cracks in theory... it's a very localized issue around the post, where the thickness matters a lot and the curvature probably not much.

A "bulge around the post" is a plastic deformation where the outside surface of the bulge is stretched the most beyond its initial condition.  That, with the slab-cut crossgrain reduced strength, sounds like a crack waiting to happen.

At least mandolins don't have the soundpost issue.

[martin swan]

2 hours ago, Don Noon said:

I don't see arching having much influence on post cracks in theory... it's a very localized issue around the post, where the thickness matters a lot and the curvature probably not much.

A "bulge around the post" is a plastic deformation where the outside surface of the bulge is stretched the most beyond its initial condition.  That, with the slab-cut crossgrain reduced strength, sounds like a crack waiting to happen.

At least mandolins don't have the soundpost issue.

No I don't think arching relates to post cracks, but a high arch will give more room for seasonal change and will probably help with EMC related cracks.

By bulge I mean a general asymmetry of the back arch favouring the side with the post ...

[donbarzino]

I currently have in my shop a violin I made 45 years ago with a one piece slab cut back.

Crossgrain shrinkage of the back caused the lower bout seam to pop and  now there is precious little overhang left,

and I see that a similar situation has occurred at the back upper bout seam and been reglued with a smaller

overhang. The back was made of kiln dried American sugar maple with nice flaming and the arching 

looks undistorted. Meanwhile the spruce top has maintained its original dimensions and overhang.

Long term crossgrain shrinkage does seem to be a problem with slab cut maple backs.

 

[David Burgess]

Expansion and contraction as moisture levels vary is greater with slabbed wood than with quartered.
Donbarzino, it was fortunate that your seams let go. Many of the slab backs I've seen had their cracks near the upper and lower blocks, because the greater glue surface area in that region prevented them from contracting.

[martin swan]

I don't for a moment wish to dismiss the facts ... slab cut moves twice as much as quarter cut.

But violins are very pliable and very restorable, and while it's unfortunate if an instrument develops spontaneous cracks during the lifetime of the maker, in the grander scheme of things it doesn't really matter.

So I think there's bound to be a difference of perspective between contemporary makers and people who deal in old instruments. Or people who deal in old instruments and those who are asked to restore them 

[cornerblockchris]

Thanks for all of your replies.

Edited April 15 by cornerblockchris
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[La Folia]

Hmmm.  Whatever the merits or demerits of slab-cut backs, I notice that Strad made quite a few of them.  I myself have a nice, very stable 97-year-old Strad copy with a slab back.

[nathan slobodkin]

I have made a great many slab backed instruments with no issues that I am aware of. Yes, I would make a slab backed instrument slightly thicker. Yes, I would expect a slightly darker sound. No, I would not make slabbed ribs although I have made a few slabbed cello ribs which I backed with linen. As I have discussed in previous threads I usually put the inside of the tree to the outside of the instrument so soundpost pressure is not lined up on the radius of the tree.