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Resawing Issues
https://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=33357		 Page 1 of 1
Author:  klooker [ Mon Aug 29, 2011 9:57 am ]
Post subject:  Resawing Issues
I resawed some Cocobolo about a month ago. I had only bought the wood about a month prior & the wood was labeled "Air Dried".

I sawed it to about 0.11" thick, then stacked it with stickers between. I did not put any additional weights on the stack. It was flat when I stacked it.

When I later checked on the wood, it had waves int it, very little twist or bow, but waves.

The grain is pretty straight and close to quarter.

So, what's the problem, internal stresses, wood was too wet, dried too quickly, sawn too thin?

Is there any hope?

Thanks,
Kevin Looker
Author:  mcgr40 [ Mon Aug 29, 2011 10:36 am ]
Post subject:  Re: Resawing Issues
I bet it will straighten fine as noted above. It just probabably needed to be more restrained whilst drying, that really seems anout all else you could do. Wood that is not really dry, when resawn, is going to have moisture gradients present- so this is an inherent danger(I think) resawing wood not fully "cured(think years)". On the the other hand, waiting patiently to cure the wood, it might crack, check, or twist, also reducing the usable pieces. Sometimes its the gold mine, sometimes the shaft. I think that is what makes the resawing portion fun-but I also like to gamble on stocks. I sort of think the super dense tropical stuff is better sawn wet since it seems more likely to degrade drying in bigger chunks. But wood in general has a degree of inpredictablility. Have fun.
Author:  Ken C [ Mon Aug 29, 2011 9:31 pm ]
Post subject:  Re: Resawing Issues
You might also try stickering your wood in the bathroom with the door closed and a room full steam. I have also flattened panels by spritzing the wood with a mixture of water and glycerin, wrapping in newspaper or paper towels, and compressing. This process may need to be repeated a couple of times, but it will flatten stubborn veneers and thin panels.

I have a pin moisture meter and check my boards prior to resawing. If the board hasn't fully acclimated, I will sticker immediately after resawing. I sticker by using sticks placed 5 or 6 inches apart with stickers above the last panel. I then lay a nice straight board on top of the stack and add lots of weight.

I resawed some koa several months ago that was really soggy with a moisture content over 20%. I had never resawed wood that wet, but it was really starting to split and check on me. I decided to resaw it wet and sticker it. Someone on the forum suggested tenting the stickered wood to slow the drying. I stacked the wood in a spare bathroom, tented it, and kept a constant eye on the humidity. Once the humidity under the tent dropped to the ambient RH level, I removed the tent. That really wet wood dried with no warping.

Good luck!

Ken
Author:  theguitarwhisperer [ Mon Aug 29, 2011 9:44 pm ]
Post subject:  Re: Resawing Issues
Maybe it case hardened and shrank unevenly.
Author:  Tai Fu [ Tue Aug 30, 2011 4:49 am ]
Post subject:  Re: Resawing Issues
theguitarwhisperer wrote:
Maybe it case hardened and shrank unevenly.


Most wood that thin I have seen behaved like that... I would think they'll be flat when glued to a proper substrate.
Author:  bluescreek [ Tue Aug 30, 2011 6:05 am ]
Post subject:  Re: Resawing Issues
when you resaw wood , it is always a good practice to store pressed or clamped flat . Wood this thin especially off quarter will do all kinds of things that you wouldn't think wood can do . I always press my wood when I resaw . Kiln dried is more stable but even that can do funny things.
It will bend back with some heat or pressing. And when you bend it, that may all be a memory
Author:  Tai Fu [ Tue Aug 30, 2011 6:23 am ]
Post subject:  Re: Resawing Issues
Yea, I think I'd be less concerned about sides warping because it will most likely correct itself as you bend. Doing it on a heat pipe actually gives you some chance at ironing them out as you bend.

You might want to obtain your wood green and saw it that way, then stack and sticker as you would any green back/side sets.
Author:  Mark Groza [ Wed Aug 31, 2011 8:37 am ]
Post subject:  Re: Resawing Issues
The wetter the wood when resawed, the more it will do that. And the more care you have to take when drying. There is also different blades for resawing wet wood than dry wood, and that has to be considered as well. I always try to wait for the wood to season before i resaw it to lessen this problem. I still use a wood press after resawing.
Author:  Ian Cunningham [ Wed Aug 31, 2011 2:57 pm ]
Post subject:  Re: Resawing Issues
It wants to be a guitar already..... :roll:
Author:  John Arnold [ Fri Sep 02, 2011 2:03 pm ]
Post subject:  Re: Resawing Issues
Quote:
wood was too wet, dried too quickly, sawn too thin?

All of the above. It is called 'potato chipping'. Dense, unstable hardwoods are most susceptible. That is why I wait to resaw these woods until I know the moisture content is down below 10%.
Anything below about 3/4" thick is risky. If the wood is in thicker form, it is perfectly fine to cut 1" boards and sticker those for at least 6 months before resawing thinner.
That is an expensive lesson I learned when cutting squared Brazilian rosewood logs before the CITES ban. I still have some backs that need to be heated and pressed to be usable. Sides can usually be salvaged because the bending process will eliminate the ripples.
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