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Anyone have good advice on how to flatten warped wood? I resawed a really nice piece of cocobolo last year for a top and then ran into a few snags, and had to put that guitar aside so I never got to glue the top on. Now the pieces are pretty intensely warped. I've read some things about putting a wet towel on it and using an iron, and a bunch of other odd sounding suggestions. I trust this community better. Anyone have a tried and true method? I can take pictures of the pieces so you can see the degree of the warp if that would help. Thanks!

I'm not sure about the workability of your cocobolo or how thick it is, but on something that doesn't take well to my local guys planer, which is just about everything but 3/4" thick maple especially, I have tried putting it in clamps, wetting it, steaming it with an an iron, and what I have found best is to sandwich between two flat boards and keep about 150lbs of weight on it. It doesnt come out perfectly flat, but after I glue it I break out my 60 grit paper, a sanding block, and my level.

Hey Gabby, how thick is it?
Pics would defiitely help.
Is it for a solid body cap?
Not a good idea, imo, to force wood to do something it don't wanna do,
unless you are bending sides or something.

i have used the iron on high heat with high steam and a damp towel before, and it worked alright. make sure you have a sturdy flat surface that you can clamp it to. clamp it down flat to a solid bench, and steam it for a while, you will actually be able to hear the board as it adjusts and the fibers move. after you have steamed it a while and its not adjusting anymore remove the heat and leave it clamped to the bench for a day or two. i dont know if this will work for what you have, but it has worked for me in the past with maple.

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~shad peters

http://www.flickr.com/photos/petersinstruments/
http://petersinstruments.blogspot.com/
http://petersinstruments.com/

The reason why a piece of wood will warp is due to moisture being drawn out of one side of the wood faster than the other side. Or, moisture entering the piece of wood on one side and not the other. This is why it's highly important to layer your wood on sticks to allow air flow to evenly pass through the top and bottom.
The cupped side of the wood is the dryer side. Its a good idea to take a squirt bottle and quickly sprits the cupped side with water. Not too much though. You don't want it dripping. Then, place the piece of wood on some sticks. Generally about 3/4" tall x width of wood. Place 3 stick on the bottom and 3 on the top of the wood followed with a scrap board on top. Then put some weight on it. I will sometimes use red bricks. Enough to give it some good weight - depends on how big the wood is. Then let it sit for a week and check its progress. It may have to sit longer, it just depends on how bad it is.
Hope this helps. I would love to hear updates on the progress of it and what you ended up doing.

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Yeap...What Josh Said....

I had a piece of very nice 3/4 quilted maple, which warped, like no ones business. I used a spray bottle, and went to it on the side which was warped (the drier side).

Then using a couple of sticks, I placed it face down, with weight on top....three days later, it had straightened out to the point where it could be glued to a piece of mahogany (for the body) and after cutting, came out perfect...

Good luck...

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Ok....I gotta ask. Aren't you guys afraid that after the wood is straightened and glued on as the cap that it will cause the guitar to cup or twist "after" you get it it built?

I have a piece of gorgeous Bastogne walnut crotch that is thin, and I was afraid to build it into the guitar???

Mike

that is not something i tend to worry about especially due to the way i normally build, for instance if i have a solid body guitar that is an inch and a half thick of say walnut and i put a 1/4 cap of curly maple of something on it, as long as the walnut is good and stable there is just about no way that the 1/4 maple is going to be able to move the 6/4 walnut, especially if its no chambered or anything. the other issue, is that as stated above the reason wood warps is due moisture, and on a solid body guitar once you spray finish on it it should pretty well prevent moisture from making drastic sudden and uneven changes. on an acoustic guitar it would be another issue entirely.

this is just my reasoning, i may be totally off.

_________________
~shad peters

http://www.flickr.com/photos/petersinstruments/
http://petersinstruments.blogspot.com/
http://petersinstruments.com/

Ahh, but I do chamber mine, and prefer to chamber. I may still give this a try though, because this piece is just too nice to let go.

Mike

i would suspsect that this would not be a major problem even with a chambered body, semi hollow and you might run into problems, but i would think you'd be fine.

_________________
~shad peters

http://www.flickr.com/photos/petersinstruments/
http://petersinstruments.blogspot.com/
http://petersinstruments.com/

Thanks for the suggestions, guys!

Alan, I'm heading out of town tomorrow and won't be back till Monday, but I'll try to snap a picture then and post it. It's probably a bit shy of 1/2" thick. The pieces are a bookmatch I resawed from a big piece of Cocobolo I picked up last year that's just over 1" thick (and 6 feet, 6 inches long). It's really pretty stuff, I'd hate to lose it to moisture issues. I'm also worried about the glue up issues others have raised, only because I've already had problems gluing up Cocobolo backs. Last year I glued up two bookmatched sets that were thin, along with maple veneer, all to use as backs for a semi-hollow I was working on. I glued up two sets in order to get sufficient thickness from them. I had been storing the pieces in my house, since the garage isn't insulated and varies too significantly in temp/humidity. But I left the pieces in the garage overnight to dry, and when I checked on them the next day, both sets had cracked clean down the middle, and separated from the pieces they were glued to. I used Titebond, which I realize now was a mistake. Should've gone with epoxy. But now I'm worried about all this stuff!

Cracks at the seam , that makes me wonder if you used any acetone on the joint to remove the resin, just prior to glue up. That is a good idea whenever gluing most dark woods.
Better luck this time

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How long is that in luthyears?

Actually, most recommendations are a freshly planed, scraped or sanded surface prior to glueing oily woods. Solvent cleaning has been proven in many tests to make for a weaker joint.

Solvent cleaning does 2 things, clears pores packed with dust from thickness sanding and removes resin. Both improve the bond.
A simple wipedown is not the proper way to do this as it can bring resin to the surface, you must scrub a bit to remove the resin. This has worked for me in building thousand of necks ,but your results may differ.
This is not the only way to do it, but I know it helps keep fretboards attached. I have done enough destructive testing (while tearing apart defective necks) to see the difference.
Do whatever floats your boat, I am just trying to save you some trouble.
Best of luck.

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How long is that in luthyears?

Alan, here are some pictures of the Cocobolo. Sorry it took me so long to get around to it. They don't look quite as bad as last time I checked on them, but still too warped to work with. The pieces are 3/8" thick.

I think my main problem is just my storage method, namely that I don't really have one. All my lumber is in my basement (hardly ideal, but better than the garage). I don't have anything stacked properly, the pieces are all just sitting one on top of the other.

Thanks Brett. It obviously works well for you. I've certainly heard much about it both ways and have weighed the advice of many who are much more experienced than I including the FWW test a couple of years back. Scraping works well for me with no failures in 10 years or so anyway. Happy boating