Warped Soundboard during build

silbery · #1 01-01-2013, 06:04 PM

Hello all,
I started building an acoustic guitar several years ago, but had to move during that time. I have the sides bent and clamped in a form that I made and the back is glued with an inlaid center strip. I had the pieces in the basement of my new house, when we had a leak from the second story tub drain. It didn't leak much, but managed to find it's way all the way to the basement where it managed to drip on my soundboard. The soundboard is quilted maple and I have made a rosette from scratch with a diamond pattern of several woods. I had already cut the soundhole and the rosette is glued in and the top has been scraped. I had started bracing the back of the soundboard when this happened to it. Now I have a soundboard and rosette with a little warping around the bottom of the soundhole, and more warping at the top and bottom of the soundboard, very near both edges. I'm hoping someone out there can tell me a way to take the bends out ot my sounboard, as I have many, many hours invested in the handmade rosette that is inlaid into it and I don't want to scrap the whole thing.
Hoping for a miracle!

Tim McKnight · #2 01-01-2013, 07:30 PM

Quilted maple isn't a very common sound board. Personally, I would never use it. My advice is to chalk it up to experience and spring for a spruce sound board. I think you will be much happier with the results.

dekutree64 · #3 01-01-2013, 07:36 PM

Quilted maple soundboard? You've got guts! I kind of want to try that myself sometime. But it's about as unstable as wood gets, so it would probably need to live in strictly controlled humidity, which I don't like so much. But I do have an Indian rosewood soundboard in progress right now, which should be similar in terms of weight/stiffness/sound quality challenge

As for your warping problem, you'll probably have to plane the braces off at least. If you're not in a hurry, just put a lot of weight on top of it and leave it for a few months. I've flattened warpy wood sets that way, by putting them at the bottom of my wood tower.

If that doesn't work, maybe try ironing it flat. Or baking in the oven pressed between aluminum plates, although make sure you seal the endgrain before that, and don't leave it in for too long or it might split from drying out around the edges and nowhere else. The goal is to heat bend it, but bending toward flat rather than a curve like you do on the sides

Hopefully the heat from flattening it by whatever means won't cause the rosette to fall apart. What kind of glue is used in it? And do you have a picture, because I'd love to see it

You'll definitely want to have good humidity control when you actually get to building it up.

Bruce Sexauer · #4 01-01-2013, 07:49 PM

To be quilted, maple must be flat sawn. At thicknesses appropriate for acoustic guitar tops flat sawn maple is inadequately stiff for the job. The instability of quilted maple takes many forms, but it is one of the worst woods for expansion/contraction in variable humidity and also has the ability to deform away from being on a plane, or modified plane, and can become genuinely 3 dimensional, other wise popularly called "potato-chipping". I would be unwilling to use it for back/sides let alone the top. Hopefully, I have helped talk you into taking Tim's advice, with which I heartily concur.

silbery · #5 01-01-2013, 09:04 PM

If I did it right, here are a few pics of the soundboard. I tried wiping the top with a damp sponge and clamping the edge I'm working on in between a couple short pieces of 2x4's to see if it will help any. This is my first try at a guitar. The back and sides are padauk, the neck is maple with walnut and paduak laminated on the head. The thing was starting to look like it was going to turn out pretty cool for my first attempt until the water dripping incident.

ZekeM · #6 01-01-2013, 09:09 PM

You weren't kidding about having a lot of work in that rosette! I do agree spruce would be a better top. Either way good luck!

nacluth · #7 01-01-2013, 09:43 PM

Like most have said, quilted maple is probably not the best soundboard tonally, but I would offer a couple of suggestions.

1. Put it upon the wall. You really have done a fair amount of work and it looks cool. My father in law has a top on his wall and it's a good conversation starter.

2. Shave off the braces, thin the maple (on the backside) down as thin as you can. It is way too thick now anyway. Like .040 in. and glue a spruce backing to it. Then thin it down to about .080 before you brace it.

3. Keep going how you are. It seems like you got some natural building skills. Personal accomplishments are great even if they're not how everyone else would do it.

KolayaGuitars · #8 01-01-2013, 10:58 PM

Quote:

Originally Posted by nacluth

Like most have said, quilted maple is probably not the best soundboard tonally, but I would offer a couple of suggestions.

1. Put it upon the wall. You really have done a fair amount of work and it looks cool. My father in law has a top on his wall and it's a good conversation starter.

2. Shave off the braces, thin the maple (on the backside) down as thin as you can. It is way too thick now anyway. Like .040 in. and glue a spruce backing to it. Then thin it down to about .080 before you brace it.

3. Keep going how you are. It seems like you got some natural building skills. Personal accomplishments are great even if they're not how everyone else would do it.

I will second this. There is a ton of work into that rosette and it could be saved by becoming a double top (not a hollow "double top" with nomex), but one of a laminate of the maple and cedar or spruce like nacluth has said. Good luck and keep us updated!

Brad

Huckleberry · #9 01-02-2013, 03:41 AM

Could the rosette not be cut out in one piece, thinned sufficiently from the back, and re-inlaid in a spruce top?

I've spoken to builders who've used quilted maple successfully for back/side woods, but all seem to have added additional reinforcement to counteract the wood's instability. It sounds like one of the worst choices for a soundboard - I'd hate to see you put many, many hours into building the guitar only or it to warp or collapse soon after it's finished...

Tim McKnight · #10 01-02-2013, 08:00 AM

Quote:

Originally Posted by Huckleberry

Could the rosette not be cut out in one piece, thinned sufficiently from the back, and re-inlaid in a spruce top?

Yes, the "lovely" rosette could be salvaged. Thickness sand the Maple top, from the back side, until the rosette becomes slightly visible from the back side. Use a circular router, Dremel cutting attachment and make a "plug" that fits SNUGLY into the Maple top's sound hole. Tape the plug onto the back side of the Maple top to keep it in place. Cut the outer circumference of the rosette out and discard the Maple top or hang it on the wall for a conversation piece. Next cut the inner edge of the rosette out. Remove the rosette.

Using the same router / circle cutter, rout a circular cavity 80% into a Spruce sound board. Glue the rosette into the cavity and place a weight on it while it drys over night. You might need to add a couple of purfling trim rings on the inner and outer edges of the rosette if you don't have an exact fit.

Level / thickness sand the spruce sound board until the rosette is flush with the outer surface. Continue thickness sanding the spruce sound board, from the back side, until you reach the desired thickness or stiffness.

Brace the top and glue the top onto the rim AS QUICKLY AS POSSIBLE. Once the top is glued to the rim it will remain more stable and will resist movement or "potato chipping" that Bruce referred to.

silbery · #11 01-02-2013, 08:33 AM

Thanks for all of the ideas guys. It sounds like I should probably scrap my quilted maple top and just try to save the rosette out of it. At least my padauk sides and back seem to still be in excellent condition, as well as the hard maple neck that I have already shaped. I was just a victim of a reduction in force as of December 7th and am still looking for a new job, so I thought it would be a good time to go back to work on my guitar. Anyone know of a place to get a nice spruce top on the cheap?

ZekeM · #12 01-02-2013, 08:49 AM

I believe RC tonewoods has some "student grade" Sitka and englemann tops for about $20 right now. Here Is a link to their site

www.rctonewoods.com

silbery · #13 01-02-2013, 09:45 AM

Thanks a bunch!

Rasmus · #14 01-02-2013, 10:19 AM

As quilted maple for acoustic top doesn't sound dramatic by itself already, your top also appears to be flat sawn.
I would never think about using that piece of wood even for a back.

I think it's obvious that you have put lots of effort into the rosette and it would probably be quite frustrating to start from the beginning again. I would make a new one (preferably spruce, cedar or redwood)

pfox14 · #15 01-02-2013, 02:37 PM

I really hate to say it, but I would scrap the maple soundboard all together. It is not quarter-sawn maple and will not sound good. I would opt for a spruce top, and would make an attempt to rout out the old rosette and re-inlay it in the spruce top. You obviously have a lot of time invested in it, so you may want to make every effort possible to save it.