Official Luthiers Forum!

I have a crack on the side of the guitar looks like maybe it was put down hard on a floor stand..
I can't reach into the sound hole and touch the inside of the area cracked. Would like some suggestions on how to repair it.

I'm not a luthier but I am good with wood working.
Currently building an acoustic from scratch so I have some knowledge!

TIA

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Steve Leonard
SEleonard

It looks like one edge of the crack is sort of stuck behind the other side. You should align the pieces before you glue them. I would make a long tool out of wood with the end beveled and curved to fit the inside of the sides. Using the tool through the soundhole, try to iron down the one edge to get them lined up. If it proves to be a bit stubborn, you might need to use a piece of wood on the outside at the same time, but pad it with some fabric so you don't mar the finish. Once the parts are lined up, I would use Glue-Boost to glue the wood and patch the break in the finish at the same time. If the cracks are not tight, you can possibly use a clamp to close them.

I am assuming you are not yet geared up for HHG.

Not geared up for HHG is correct......do not know what that is!
I like your idea of getting it lined up. Could CA glue be used?

_________________
Steve Leonard
SEleonard

Ok checked out a video about glue boost. Thanks for the info.
How would I determine what finish was used? This is a 2003 year martin, j15-12 jumbo mahagany top
TIA

_________________
Steve Leonard
SEleonard

The guitar is not bound, it looks like the bottom crack might be at the top of the kerfing. After using Barry's method of getting the pieces all even you might be able to put a piece of gauze surgical tape on the end of a stick and work it into place over the cracks with a second stick. Then wick thin CA into the crack and try to drip some onto the gauze on the inside. You'll have to be creative with lights, mirrors, pieces of wood... Prop the guitar at an angle so you can drip the CA directly onto the crack and gauze.

I use Gluboost for repairing fairly thick modern finishes but probably wouldn't use it here. Water thin CA (StewMac #10 or equivalent) will wick into the crack and flood the gauze - it might not be necessary to reinforce it but I think I would try.

Your guitar should have a satin nitrocellulose lacquer finish - that can be drop filled and touched up with more lacquer. Sand thru the stages but don't do the final polish - you might want to use fine steel wool or micro mesh for your last stage.