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1987 Flatiron 3K
Broken Back Brace
© Frank Ford, 2/29/00; Photos by FF, 4/25,00

Here's a little job that went quite well. The instrument in question is a 13 year old Flatiron 3K mandolin with figured koa back and sides. It was in its gig back when it was stepped on (rather lightly, I suspect). The single transverse back brace broke loose, and jammed into the side, presenting an interesting challenge.

As you look at the photos, you might notice that the pictures in the mirror are reversed. I did that to make the inside views look a bit more natural.

The first look inside is a bit deceptive. Not much damage showing here.

A little closer inspection reveals the broken brace.

And, outside, the real trouble is visible, where the side and lacquer were cracked by the brace as it jammed upward. I assume that the back had shrunk a tiny bit with age and dryness. When the brace moved up beyond the level of the lining, the side couldn't hold it in.

It takes a mirror to see this brace because the instrument is so shallow, you can't get a straight view.

Close up, you can see the linings pushed up, and the brace sticking into the side. It is really jammed there, with no hope of pushing it back in place.

So, I figured I'd have to cut the brace short to make it fit again. I started by cutting a little section of my thinnest X-acto saw blade. I used the carbide cutoff disc on my Dremel.

I had a spare banjo truss rod in the scrap bin. It's a simple 3/16" diameter steel rod, so it was easy to hacksaw off the threaded portion and slice it lengthwise about 3/8" so I could solder my little saw blade in place.

It's just the same electrical soft solder I use for pickups, but it's plenty strong enough for this job. The portion of the blade near the solder joint was heated enough to anneal it, so it was safe and easy to bend it to the angle I needed inside the mandolin.

Here's the mandolin, clamped in my Versa Vise, with the light and mirror taped in position so I could work with only two hands.

My only view was reversed by the mirror, so it took a bit of juggling to get the tool in position.

Here it is, right at the end of the brace. Once I got the whole thing set up, it was a breeze to cut the brace off. I cut about 1/8" off the end, so I'd be sure that the brace would clear any bits of lining as it went back in place

Clamping it way down at the end was less tricky than I expected, because I was able to lever against the upper brace. Glue (Titebond) squeeze-out cleaned up nicely with some bits of moistened paper towel held in a hemostat.

The lever is my fret file. When I'm clamping up, I'll grab just about anything that looks like it will help the job along.

The last thing was to place a new piece of lining above the brace to resist any future foot damage. I made up some peanut butter thick epoxy and buttered up my new support block. Stabbing it onto a sharpened rod, I could easily place it where it belonged.

Job done. The thick epoxy will make up for the fact that the surface was uneven, what with the bits of lining still stuck there. The block also served to reinforce the inside of the cracked side, which had sprung right back into alignment.

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