The Bench @ Keystone: Saxhorn Dent Removal

A regular customer who plays in a Civil War band brought in this over-the-shoulder tenor saxhorn that had taken a bad hit on the upper bow. The resulting dent was so deep that it almost closed off the tube, rendering the instrument unplayable.

It would've been a neat instrument to work on even without the dent work. We dated it to sometime in the later 1800's, although it fits as a Civil War era instrument as over-the-shoulder horns were patented in 1838 and had become commonplace among brass bands in the 1860's. We call them saxhorns, as the musicians did at that time, although strictly speaking saxhorns were patented by Adolphe Sax in 1845 and of a very slightly different design. True saxhorns were more commonly upright instruments, though marching musicians preferred these over-the-shoulder instruments because they were easier to carry. This one uses Berlin valves, an early piston valve design from the 1830's that also fits with the period, though apparently over-the-shoulder instruments more often used rotary valves.

The other notable thing about this instrument that will forever burned into my memory is that the brass was t-h-i-c-k. Whatever caused that dent must have fallen out of an airplane or the space station to have left that kind of damage. Anyhow here's a little photo essay of the process.

The dent was in the upper bow, indicated by the white line, which had to be pulled off. As a bonus, the leadpipe coming out of the 1st valve casing also came off in the process. Great!

The tube had to be annealed to soften it, then the first part of the dent removal process was to raise the dent enough that a ball would be able to pass through it on the inside. That meant soldering a brass plug into the center of the dent, chucking the plug into a vise, and pulling on it until the solder failed and the plug let go. That process was repeated three times to get to this picture. Prior to that the dent was so deep that there was a danger of the brass folding over itself as the distortion was raised. This process mitigated that risk.

After working several graduated dent balls through the dent, the surface is smoothed out some but the area is still significantly distorted. The tube has to be repeatedly annealed to soften it, as the process of repeatedly hammering and reshaping the metal is constantly hardening the brass.