Gibson lost his head(stock)

If you have a string instrument of any kind that needs fixing, a mistake you made in building a new instrument that you need to "disappear," or a question about the ethics of altering an older instrument, ask here. Please note that it will be much easier for us to help you decide on the best repair method if you post some pictures of the problem.
David King
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Re: Gibson lost his head(stock)

Post by David King »

Very nice work Mario.

Mario Kessels
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Re: Gibson lost his head(stock)

Post by Mario Kessels »

Spent some (a lot) of time this today on reshaping the neck. Worked quite well, it looks ok I think.
I am not sure whether or not to install some reinforcements now.
I learned 2 things today:
1) Plan how you have the grain running with regards to preference of shaping later in. Towards the headstock or away? With mine the grain was running so that I had to work away from the headstock which does not have my preference.
2) Pearl Jam really is a great band. . Actually I knew that already. The playlist was finished before I was done shaping, that was a surprise.
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Mario Kessels
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Re: Gibson lost his head(stock)

Post by Mario Kessels »

I have agreed to put some reinforcements in. I have done this before on similar neck repairs. Did it by hand those times, cut out 2 slots and inlayed splines.
I am wondering whether or not to make a jig to use the router for cutting the slots. Is it worth it? Does it make a difference really ? I guess when its made right it should make the job a lot easier. If I make the jig should I make it concave or straigth?

What's your opinion on this ?
I have thought a bit about the backstrap option that Barry mentions. This could also be an option but since I have no experience with that at all I am more inclined to go with the splines.

I have tested the repair quite aggressively and it is defenitely as strong as it was before so it's more an upgrade than anything else. Doesnt mean its not necessary though since it was not good enough to start with.
So:
Yes splines
Jig ?
straight or curved?

btw I have used the paint mixing wooden sticks that you get often when buying paint etc. I do have ebony etc, but those sticks seemed to be super stiff and strong in the direction I wanted and have a nice uniform width

appreciate your feedback

David King
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Re: Gibson lost his head(stock)

Post by David King »

If the paint mixing sticks are maple or beech that should be OK. Over here they are mostly basswood or poplar which wouldn't do much.
I don't think a curved routing jig would be practical or beneficial. Your problem with routing is going to be finding a router bit that's long enough and narrow enough. Perhaps a spiral cutter from a drywall opening tool if you could get the correct router collet. You would want high speed steel cutters as they are both sharper and much less likely to snap off than carbide tooling hence safer too.

If you had access to a small table saw you could possibly park the neck in position over the blade and raise the blade slowly into the back of the neck and headstock. But really that still leaves you with the problem of a curved slot and a wood spline that has straight grain similar to your current mahogany splice so what have you really gained? Inlaying CF under the wood is marginally better but you really want the tensile strength at the very back of the neck/headstock which is why a back strap is popular since the wood fibers are continuous around the curve.

I really like the thin layer of CF cloth or unidirectional ribbon than can be draped over the compound curves and vacuum bagged or taped into place while the epoxy sets. You can use a very light 2oz or 4oz cloth that might add .02" (.5mm), be completely reversible, and add both torsion and sheer strength to the joint.
You would need to sand the finish off part or most of the back of the headstock and a ways past the graft on the neck. Try to keep the serial number intact obviously.

Mario Kessels
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Re: Gibson lost his head(stock)

Post by Mario Kessels »

Good feedback David. especially what you are saying about putting splines, where I just replace wood with wood. The glue surface angles are so shallow that the grain is long enough and the glue joint strong. To make it stronger i have to do a bs or do the cf thing.
I have got the cf, epoxy and peelply already but i dont have a guitar to test it on...have to think about this a bit more..

David King
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Re: Gibson lost his head(stock)

Post by David King »

Mario,

Testing it out is a really good idea. You could fashion a replica out of common lumber and practice on that first. PeelPly is great stuff. You could wrap medical gauze over the peelply to squeeze out as much excess epoxy as possible. I would also use a petroleum based furniture wax on the fingerboard and anywhere else you don't want the epoxy to stick. The hardened gauze wrap should peel off the peelply and the peelply should peel off the neck but you want to make sure of that!
To achieve the maximum tensile strength of CF fiber you want to stretch it out so that the fibers lie straight. I'm not sure how you could do that so I wouldn't worry too much about it but that's the theory.

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