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If you see rust, its not the aluminum that is rusting. Real quick experiment for you. Clean up a piece of steel and get a piece of aluminum, spray them with a saturated solution of granular fertilizer like 13-13-13 (dont work with fertilizers and mixing them with liquid unless you know the warnings very well, some aluminum roofing materials have an oily residue to prevent oxidation and doesnt need to mix with some fertilizer) or just spray some salt water on the two and come back in a day or so and check them. Youll see the steel rusted and the aluminum didn't. If the aluminum did rust......then itis an alloy of more than aluminum.
Aluminum doesn't rust. It will oxidize, but won't rust.
Titebond also makes a "Hide" Glue that I would recommend for use in Luthier work.
Well there's a little difference in the wood glues. In Cabinets and millwork I use Titebond III or Elners Exterior Wood Glue (Gel/No Run formula). For Luthier work.....add Smith's All Woid Epoxy in the mix. The difference in the Smiths is gonna be better Sound resonance and transference with instruments; which is something you dont have to take into consideration with Cabinets and Furniture. Titebond and Elmer's are naturally going to take stain and finish better as far as cosmetic aspects are concerned, but you can cosmetically adjust once expoxy is used also.
If you can open it up a little, you can use a syringe designed to use with glue and it should be fine. I wouldn't complete the break if it was mine (not on an instrument, furniture maybe), you need as much natural fibers/grain to remain in tact if possible. As far as glue, Titebond III (it is water resistant and a great wood glue). Or Smith's All Wood Epoxy, which is a 2 part catalyst type. Both you can use in a syringe to apply inside your defect.Hope that helps you a little.
By the way, be very careful with gorilla glue, it has it's uses, but when you use it correctly by applying dampness to parts being repaired it will use either the moisture you pretreat with or in the atmospere and expand like a son of gun, whick will literally break the piece you are trying to repair worse than it was.
You can use Titebond III and it would work really well. In your specific application though, I would use Smiths All Wood Epoxy, it is a 2 part system. I suggest Smiths because you are repairing an acoustic and because you have some wood missing. Smiths has a better sound transference than Titebond and Smiths also has better filling properties, which will help in your application on the missing piece. It cures super hard. Good luck to you on it. You'll do fine.
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