Another "top-sag" question

[Bernie Daniel]

A well known, and highly respected luthier (or really string instrument repairman) in our area recently suggest to me a new way to alleivate the sag of on a Gibson oval-hole mandolin.

This topic has been discussed here before as older oval-hole mandolins (both A- and F-style) seem to be prone to top deformation under the bridge from the string tension. #

Among the fixes commonly mentioned are: 1) to check/reglue the transverse brace; 2 the install x-bracing; 3) carve a new top.

I have also seen speculation on inserting a sound post (like a violin) under the bridge. #Most seem to feel this approach would not work out well -- but at least one person claimed to have tried this and in did not affect the sound of the instrument.

However the possible fix suggested by this particular repair person would be to install a new longer transvese brace directly under the bridge. #He asserts that he can do this through the sound hole (i.e. without removing the back).

Futher he thinks this would not be likely to cause much sound deterioration in the mandolin. #This seems like a great idea if it would work.

Have any of the luthiers/repair folks out there ever tried something like this? #If so what happened? #Thanks.

[Frank Ford]

Here's my most recent and most successful version of that particular repair:

http://www.frets.com/FRETSPa....ag.html (http://www.frets.com/FRETSPages/Luthier/Technique/Mandolin/Structural/MandoTopSag/mandotopsag.html)

[sunburst]

I have installed an additional transverse brace in an old Gibson oval hole, working through the sound hole.
It got the instrument playable again, the sound wasn't hurt badly, and in fact is better because, well, it's playable. The brace is removable if anyone ever wants to take the mandolin apart and install an X-brace.

Whether or not the "vintage" value was affected, I don't know or particularly care. It was a broken down, un-playable instrument, and it is now a useful mandolin because of a brace that can be removed to restore it to it's former collapsed condition if someone is worried about that on down the road. The sound is in line with many other oval holes, not drastically different from many "healthy" examples.

[Bernie Daniel]

Well those are two outstanding answers to the question.

The step-by-step on the creating and insertion of the brace are quite amazing Frank. #That mandolin top jack is so cool. #

I wonder what method you used for placing and gluing your brace John? #Also did you go with a similar kind of laminated strip?

Mandolin Cafe has to be the world source of mando knowledge. #It seems safe to say that almost anything you might want to know about mandolins is covered here - in multiple layers.

Thank you gentlemen. http://www.mandolincafe.net/iB_html/non-cgi/emoticons/smile.gif

[sunburst]

I've since gotten a digital camera and started "documenting" more repair procedures, but I don't have any pictures of the brace "addition" to the Gibson.

I made a spruce brace very similar to the original cross brace but longer, not a laminated strip. Honestly, I don't really remember how I jacked the top or fit the brace to the underside of the top, but basically, I jacked the top back to it's full arch and glued the brace to hold it there. I probably made little posts, or props, of the correct length to go between the back of the mandolin and the brace, and then clamped the joint from the outside of the mandolin with those posts in place.

[Steve Ostrander]

Good luthiers amaze me. The patience and ingenuity you guys have is incredible.

Well done, folks!

[BlueMountain]

That tool of Frank's is one of his inventions that LMI should be offering for sale. Ingenious and useful. And a very nice fix, too.