Crackobolo questions/advice
 

I have a guitar in the works with cocobolo backs and sides.

Thicknessing of the back has revealed/(caused?) a crack. It was fixed with CA, but upon continuing the thicknessing, another has appeared. Best I know, the wood is well dried/aged, so I’m hoping it’s not a matter of moisture. There’s been discussion of doing a CA wash, but I’m wondering if that will impact sound. I’m also wondering if this will really be a long term fix. I’m curious to see if you guys know of other solutions.

Thanks.

If it was me, I would start the back over again - it seems a bad idea to build a new guitar with two repaired cracks already.

Photos of the cracks/wood would help in understanding the issue.

Sometimes, cracks can easily be repaired, if necessary with reinforcements on the interior side of the wood. Not all CA glue is of the same quality/effectiveness. Depending on the crack, I'd use wood glue (e.g. Titebond).

Factors to consider in choosing whether to scrap or repair include what you paid for the wood, the quality of the wood, how rare is that particular piece, the environmental controls during the building process - you are paying attention to the humidity levels during building, right? - and so on.

Noted archtop guitar maker Benedetto, during his making of an instructional video series, broke one of his sides during bending. In the video, he simply glued the crack and carried on. His instruments, at the time, started at about $18k. I'd have scrapped the side, but he didn't. No doubt it came out okay. Yours might also.

Repaired cracks are probably more common than people think.

Just glue it and keep thicknessing, its not a big deal

Steve

I don't think the CA wash would affect the tone, as the CA would only seep into the cracks, and you can sand back down to bare wood. I'm actually a bit surprised, as cocobolo has a relatively high oil content and is one of the more stable woods out there, unless the board is very, very old?

Wouldn't the CA also get into the pores?

you could think of it as pore filler but I wouldnt want to smell that much CA

Cocobolo pores are pretty small, so unless your plate is the exact thickness, you'll be sanding it away. Cocobolo is so dense, some pieces will sink in water; so I don't think a milligram or so difference in weight is going to matter. Or, you could get another expensive piece of cocobolo!

If the back cracks seem to be getting worse or are stressing you out give RC Tonewoods or another supplier a call, it's very possible they may have some extra back sets around. I got a side set to replace a broken side, matched beautifully and they gave me a good price. You would have to send them a good photo of course.

I've always wondered about a CA wash too. What I was thinking though was more using CA as a filler. That way you fill and you *might get the benefit of crack protection. I don't think it would impact the tone at least compared to any other type of finish, sealer, or filler.

I've thought the same. I've seen enough wenge split and crack that this was going to be my CA wash/pore fill trial wood. It also has those giant pores. Other than the vapors and mess, I would think it would work well.

Couple options you might want to look into:

http://www.bsi-inc.com/hobby/super_gold_plus.html
https://www.starbond.com/all-product...ant-no-05.html

Thanks redir, I had not run into these products yet.

You are correct, it does work nicely. I've even considered CA as a finish. A fan behind you makes it almost easy.