Quarter Sawn vs Flat Cut

Wood selection sound-boards, backs, sides, necks and trim
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Rossecho
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Joined: Sun Jan 19, 2025 12:23 am

Quarter Sawn vs Flat Cut

Post by Rossecho » Sat Mar 22, 2025 11:11 am

This is question about how bad did I screw up. I am very new to the notion of building guitars. So I am learning everyday. I have taken a deep dive into the subject and found out I might have screwed up on a recent wood purchase. I have a litttle experience with sawmills and got the idea that I could cut tonewood soundboards from slab wood. Well my research has shown me that it might not be a good idea. The advantage of the Quarter Cut is that the grains being perpendicular provides stability and resisting to cupping and warping. With Flat cut material you will get warping and cupping. Saw a video where a master woodworker said that Flat sawn wood should be glued and constructed in 3 sections. The 3 sections play against each other and reduce the movement of the wood. Otherwise they will shift and move over time. The guy even went on to explain how quarter cut and flat cut lumber should be arranged within a piece of furniture to make a strong stable piece.

All that said, before I learned all of this I purchased about 240 Board-feet of slabs. Can I salvage the situation, besides turning the slabs into coffee tables? The real question is can I make a 3 piece guitar back, which would go against "Guitar Making Tradition & Technology" and have a viable instrument?

Herman
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Re: Quarter Sawn vs Flat Cut

Post by Herman » Sat Mar 22, 2025 12:56 pm

Slab cut wood for soundboards is not a very good idea. It can react in a unwanted way indeed.
But hey.... If it is your first.. what the heck, give it a try. Your first is not the best you will make in time anyway.
FWIW: After many years I know my first was way overthought. Build and learn is my advice.

But reading your post...Is it for a soundboard top or a back?
And what wood is it?
Herman

John Parchem
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Re: Quarter Sawn vs Flat Cut

Post by John Parchem » Sat Mar 22, 2025 6:14 pm

I think you can get away with slab cut for the back as it is relatively heavily braced. Sometimes slab cut wood is funky to bend as it reacts to heat and pressure differently. It is easier to get cupping even in a side bender. Also three piece backs are fine. They may look funky if you alternate the direction.

Carl Dickinson
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Re: Quarter Sawn vs Flat Cut

Post by Carl Dickinson » Sat Mar 22, 2025 9:01 pm

Slab cut glued on the flat together and resawn becomes quartersawn. Works good for necks but maybe not for backs and sides. :roll: John's point that the bracing might help on backs and sides is something I've used with success.

Rossecho
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Re: Quarter Sawn vs Flat Cut

Post by Rossecho » Mon Mar 24, 2025 12:51 pm

Herman wrote: Sat Mar 22, 2025 12:56 pm Slab cut wood for soundboards is not a very good idea. It can react in a unwanted way indeed.
But hey.... If it is your first.. what the heck, give it a try. Your first is not the best you will make in time anyway.
FWIW: After many years I know my first was way overthought. Build and learn is my advice.

But reading your post...Is it for a soundboard top or a back?
And what wood is it?
Herman
I was going to use it for backs and sides. The species is Monkey Pod, Samanea saman,. My thoughts at this point is to cut thin pieces and use them like veneer. I got some cheap mahogany and this might make a good combination until I can find some quarter sawn wood to work with.

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