View Full Version : How to Repair a Loose Back and Tone Bar

Jan-29-2004, 3:52pm
I have an old A-style mandolin fom the 1930's. The back is starting to separate (it's come unglued). The mandolin may also have a loose tone bar (it only has one, mounted horizontal across the top).

What is the best way to repair the mandolin? Remove the back? If so, what is the best way to do this? Then what? Lightly sand the edges and re-glue? What kind of glue should be used?

Thanks all!

Darryl Wolfe
Jan-29-2004, 4:01pm
This is a difficult repair, but is addressed fully at frets.com

brace repair (http://www.frets.com/FRETSPages/Luthier/Technique/Mandolin/Structural/MandoBrace/mandobrace.html)

back repair (http://www.frets.com/FRETSPages/Luthier/Tools/BenchClamps/benchclamps.html)

Have fun

Jan-29-2004, 4:27pm
Good link, Darryl. Frets.com has a LOT of info.
The hard part of the repair is re-aligning the rim after the instrument has been taken apart.
I built a jig some years ago that works pretty much the same way as Franks method. It is a piece of 3/4 in. plywood, cut out to relieve the arch of the back or top. Fastened to the surface of the plywood are pieces of wood that completely surround the mandolin. Screws driven through these pieces of wood serve to align the rim. The surface that the mandolin sits on is padded with cork gaskit matrial so that the back (Or top) can be clamped in the jig while being glued in alignment.
This discription may not make this jig too easy to visualize, but it works. It can be used for "A"s or"F"s, can be set aside when not in use or while glue dries, and I find that I usually need to apply alignment pressure pretty much all the way around a rim for good alignment.

Feb-07-2004, 1:58am
Well that is very interesting. I have a teens Gibson on the way to me with exactly the same problem only more so. About one third of the back is off and the sides are all pushed out.
I was going to take it to a repairman although I was not sure how big a job it is and how much it would cost. Now maybe I will give this method a try.
One thing I am not sure of though-- hide glue.
Would this be a scary proposition for someone who has never used it before??
Well, I will answer that one myself--of course it would.
What are the alternatives?? Is there some other product that you could use on a teens Gibson or would that just be ruining the vintage integrity of the mando?
Any advice would be appreciated.

Feb-07-2004, 3:16am
I have seen several of these on ebay that the sellers try to play it off that this is a simple repair. Often called "luthier specials" like someone really wants to buy damaged mandolins. Maybe we should sic Dale on them.