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Like the violin maker's classic "chest patch"
Rebuilding a "Cave-in"
© Frank Ford, 10/9/98; Photos by FF, 5/1/98 - 10/8/98

Here's a tough situation.

This mandolin had apparently been dropped on its end pin, either in shipment or before. The musician who purchased it from an out of state dealer didn't notice the damage, and tuned it up to hear a loud "crunch" as the end block pushed forward and the top collapsed ahead of it. Now, he could have claimed the damage to the the shipping company, and would have been able to recover his purchase price.

But he didn't, and for a very good reason. This may possibly be the only Gibson A-4 from this early period (around 1906) that was an original left handed instrument. So, he could have gotten his money back only to lose the instrument. He chose to have it restored instead. Sure, he'll have paid for it twice, but that's hardly the point when you consider that it's a unique and irreplaceable instrument.

There are less expensive and esoteric ways to repair this kind of damage, but this is the traditional way to ensure good structural integrity without sacrificing form or function.

Here's the venerable A-4, with its original double inlaid pickguards:

It's hard to see the damage because of the original black finish:

You'll get a better view from the inside.

In order to have a really solid work board for this damaged area I'm making a plaster cast:

I've mixed up some regular plaster of Paris and poured it into a zip lock bag. That way I can just lay the bag on the mandolin and squish to down lightly with a board. The board will leave the back side of my mold flat so I can glue the board on for extra strength.

Here's the plaster mold, right off the mandolin:

The wrinkles in the bag are not in the area where I'll be working.

With the plastic bag off, I think you can see that the plaster molded right into the damaged and cracked area:

I've glued the plaster to the board and cut away the excess, leaving only enough to cover the area in which I'll be working:

I'm sanding the mold with a contoured block, checking with a contour gauge, to correct the arch of the mold. I want to rebuild the broken area to look as though it had not caved in, and this is my opportunity to make any adjustments in the arching and contour of the area.



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