MIMF

Hello,

I got this rosewood guitar set from my local Woodcraft. It had been there a long time and it was finally on sale. I didn't pay a lot for it and this is the first set I've ever purchased. Since it is rosewood there won't be many like it sitting in stores very often anymore. Here's a pic of the set.
What I didn't notice when I got it was this warp when set as a bookmatch. Is this common for guitar sets? Can I use this set? If so how do I deal the the warp? The gap at its peak is 0.23"/5.8mm.
Thanks for any suggestions.

-Eric

No, that is not common and not good. How about putting the center joint on the opposite edges?

Barry Daniels wrote:No, that is not common and not good. How about putting the center joint on the opposite edges?

Ugh, the other edges are a bit better but still not straight. Is it hopeless or would an attempt to straighten them with a heat source and clamp flat be worth the effort?

Thanks for the reply.

-Eric

Eric,
might just be me, but I wouldn't build with that back set. Just too much tension and movement for me to risk. Save it for headplates.

I would let it set in your shop, stickered with a weight, for a while and see what happens. I had a piece of rosewood like that curl up into a bowl when I wiped one side with water to see the grain. A month or two in the shop and it was flat again.

What I would do (not to say it's correct - it's just what I would do) is wet the concave side of each board and see if they straighten out temporarily. If so, I would make the joint and glue them while they are straight (may have to re-wet/clamp.) If this succeeds, thickness, cut out the back and glue the braces in. Then let this "rest" while I construct the rest of the guitar and see if it's still in good shape when it's ready to close up. At the worst you've wasted a little time, learned something, and just have to make a new back (that probably won't match the sides though.)

Peter Wilcox wrote:What I would do (not to say it's correct - it's just what I would do) is wet the concave side of each board and see if they straighten out temporarily. If so, I would make the joint and glue them while they are straight (may have to re-wet/clamp.) If this succeeds, cut out the back and glue the braces in. Then let this "rest" while I construct the rest of the guitar and see if it's still in good shape when it's ready to close up. At the worst you've wasted a little time, learned something, and just have to make a new back (that probably won't match the sides though.)

Thanks, that seems like a reasonable approach. Would you use any heat? It seems to my rookie senses that I could use my bending iron a little to flatten them and then clamp them flat. This seems like the reverse of bending sides and clamping into a mold. It works for bending and I'm wondering if it would work for flattening. Since I have this set, and will keep it, having a learning experience is a good goal.

-Eric

Using the bending iron sounds like a good idea to me, and if successful would make the straightening more permanent.

I've seen these sets at woodcraft before and they were bundled together with the book match closed. If you didn't notice the bend, it may not have been that severe in the store. Once you opened the book in your shop it started moving. As others have said, I'd prop it up in the shop for a while and see what happens. If it doesn't get better, you have nothing to lose by trying to flatten it. I would probably try a clothes iron. Not the one I intend to use on clothes again though since it will get rosewood oils all over it. I'd try to get it ironed flat and clamp it flat while it is still warm and let it set for a good long while. Kinda' the opposite of side bending.

Once I joined the halves, I would probably let it set around for a good long while to see what happened. So do it all now and set it aside until you are ready for this build.

Thanks for the replies. I'm going to try several things with this back set. First I have lightly clamped them flat and sprayed a little water on the concave sections. I'll leave them that way for several days to see if there's any change. If there is a change I'll be encouraged. If not I'll try adding some heat.

I think this set was wrapped tightly with that stretchy clear film that sticks to itself. Wherever it was really tight is where it is warped now. I'm hoping I can reverse this. I can be very patient, I have plenty of wood and shop reorg tasks to keep me busy.

-Eric

The wave in the grain is clearly where it wants to move, so if you can flatten it then I'd join the opposite edges. The unstable part would then be glued to the rims, which should resist movement once it's thicknessed.

Also, the wave looks very like the waist of a guitar, so you could design the body around that wave.

I would try heating and clamping it to shape. Don't use the moisture trick. I used that once to flatten a piece and when I built with it, it showed up worse than ever. use dry heat and clamping, then I think you could use it. Ervin Symogi wrote about how he clamped warped Brazilian Rosewood between two large metal sheets and heated them, the wood was like a potato chip before that, and they came out flat.

Mark Swanson wrote:I would try heating and clamping it to shape. Don't use the moisture trick. I used that once to flatten a piece and when I built with it, it showed up worse than ever. use dry heat and clamping, then I think you could use it. Ervin Symogi wrote about how he clamped warped Brazilian Rosewood between two large metal sheets and heated them, the wood was like a potato chip before that, and they came out flat.

Oops, I already did use a little water. The set is still rough so I hope any discoloration will come out. I didn't see anything after it dried so I might be lucky. The good news is that after wetting and clamping overnight the warp was smaller. I'm taking this as a good sign and will try heat next.

Thanks,

-Eric

Bryan Bear wrote:I've seen these sets at woodcraft before and they were bundled together with the book match closed. If you didn't notice the bend, it may not have been that severe in the store. Once you opened the book in your shop it started moving. As others have said, I'd prop it up in the shop for a while and see what happens. If it doesn't get better, you have nothing to lose by trying to flatten it. I would probably try a clothes iron. Not the one I intend to use on clothes again though since it will get rosewood oils all over it. I'd try to get it ironed flat and clamp it flat while it is still warm and let it set for a good long while. Kinda' the opposite of side bending.

Once I joined the halves, I would probably let it set around for a good long while to see what happened. So do it all now and set it aside until you are ready for this build.

Thanks for this input. I have an old iron I use in the shop and I have a heat gun. I looked at the back set in the other bookmatch orientation and it does indeed look good. If I can straighten and join them I will definitely let them sit for a long time. I have plenty of wood to make my initial bad guitars with.

-Eric

I've had this rosewood back set clamped flat since I first asked about it. Here's what it looked like then.
Here's what it looks like now.
It has lost a lot of the warp already and I haven't done anything drastic. If I flip the bookmatch it looks like this.
That seems to be close to good. The back would look like this that way.
Do you wizards think this is salvageable now? I'm encouraged but still at the clueless rookie stage.

Thanks,

-Eric

That would absolutely be the best orientation for the book match. I am still not crazy about the wrinkle across the grain. But placing that at the waist would minimize the grain distortion because it would be at the narrowest point and less of it would be present after cutting the shape out. So that would lessen the chance for distortion.

I agree with Barry. That would be the safest orientation if you choose to use it. It also happens to be the nicer looking orientation IMHO. I might even flip it over having the heel end on the part that is now in the bottom of the picture and the tail end on what is the top. I often will decide what to make based on the wood. In this case I would be looking for a body size/shape that put the waist in a place that compliments the grain where it comes together. Flipping it as i described might put the smaller lower bout in the worst part of the buckle further reducing problems.

I bet if you drew an L-00 pattern on that with the tail as close to the top end of the picture you'd fall in love.