Thursday, May 28, 2009

Crack Back

If you've been following the process of building guitar #003 you probably noticed that when I got the jointer out and used it on the neck and the top I didn't also use it on the back. Normally I would have joined the bookmatched back pieces together right after doing the same with the top, since it's the exact same process and I already have everything out that I need. But I didn't, or couldn't, and here's the story on that.

When I first received the wood for #003 everything looked great. A couple of weeks ago I was showing the zebrawood to someone and noticed what looked like a crack near the top.

Sure enough, there was a crack, and it went all the way through the wood. Then I noticed that there was a corresponding crack on the other half. Here's the crack on the right half:

Not so bad, but here's the one on the left half:

Very noticeable. When folded the two pieces back on each other they match, so it's clear that this is a weak area of the wood, and in the 2-3 months since I received it, this weak area gave way. When I flipped the left side over, the crack looked like the one on the right side, and vice versa. In other words, both boards had a side where the crack wasn't so bad and a side where it was really ugly. Problem is, in orienting the sides bookmatched, one board always had its ugly side up.

I thought maybe I could orient the pattern such that the ugly crack fell outside of the cutaway area, but that didn't work, and the mild crack is just mild in comparison to the ugly side; it's still noticeable.

Since the cracks go all the way through the wood I wasn't able to sand through to solid wood. I'm stuck with a couple of cracks in the back.

This was on a Friday late in the afternoon, so I call the supplier, Luthier's Mercantile International, out in California and talk to Chris, the sales manager. I explain the problem to him. He says that when they get cracks in wood that they use super glue to solidify the cracks and keep them from spreading. If it's just a hairline fracture with minimum separation, after sanding it's invisible. But since it's been a few months since I receive the wood there wasn't much they could do. I told him that I would give it a shot but I was skeptical because there did appear to be separation and because the crack went all the way through. I asked him if I could buy just another back set if that didn't work, or would I have to buy a whole back/sides set. He said that it would be difficult to break up a set, but if need be he would check and see.

So I tried the super glue and sanding, but it didn't work. Well, more accurately, it solidified the crack so that the two back pieces are structurally sound, but it actually made the cracks more noticeable and ugly. It's simply a cosmetic issue, and it's on the back where it won't be seen that much--but the more I thought about it, the more unacceptable it became. I couldn't ask Clark to accept something that I felt just didn't look right.

By this time it's 5:30 out in California and LMI is already closed for the weekend, so I just have to live with it for a while. Clark comes over the next morning to makes some choices on binding materials, and I can't bring myself to mention it to him. I decide that on Monday I'll call Chris up and order a whole new back/sides set. Since the original set is structurally sound I'll go ahead and use it for some future guitar and either keep it myself, give it away, or sell it on eBay with full disclosure on the cracks.

Monday afternoon I call Chris at LMI and tell him that the super glue fix worked but just doesn't look good, so I'm going to need to replace it. I ask him if he thinks he can just sell me the back, and he says yes, and then surprises me by saying that he's going to replace it at no cost.

Chris at LMI is the MAN! And I tell him so.

He has me email him a picture of the original set so he can make sure the back he picks is a good match for the sides. The next morning I get an email saying that he has found a good set for me, and after he gets it sanded down to proper thickness, he'll send it out.

Well, it finally arrived yesterday, and it matches the sides quite well. Here's a picture of the new back:
You'll notice at the bottom of each side there is a knot where there used to be a branch. There's actually a small hole there, but this area falls outside of the guitar shape and will be cut off and thrown away, so it doesn't matter.

I thought about putting these edges together with the knot at the top:

The knot would still fall outside the guitar shape, but at the very top of the back there would be that very nice figure where the grain goes around the knot and then converges back together in the middle.

However, in this orientation the boldest lines are on the outside and a lot of them would fall outside the guitar pattern. Other than the converging grain lines at the top the grain in the middle is rather homogenous, so I decide that the other way is the way to go. Besides, Pam says that those converging lines of grain "look like a butt-crack. You can't have a butt-crack on your guitar."

OK, she's right, but I think it's clear where Austin gets his.

Clark, I know you are reading this so if you want it the, ahem, butt-crack way, give me a call.

It will be a very striking and beautiful back. The braces for the back have already been cut, so I'm going to join the back as soon as I can and brace it as soon as the humidity allows--looks like I may have to wait until Saturday--and hopefully that will stabilize the wood and prevent any cracks from developing.

Someday I'll use the original back for something. I'll just order some sides to go along with a top that I didn't use because I didn't like the way the soundhole turned out, and I'll have a decent guitar with a couple of "character marks." Sell it on eBay, give the money to Water4Christmas. Yeah, that sounds like a plan.

Chris at LMI. I'm tellin' ya, he's the MAN!

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