A dented bell restored to its original state.
A “P. Mauriat” alto sax came into the shop this week. The owner was playing a gig, and the horn fell off its stand and onto a monitor speaker. The result? A lot of bent keys and a big, ugly dent in the bell.
In this article, I’ll explain how the dent (along with a few other problems) was repaired. Normally, when repairing brass (horns, keys, tone holes) we can reshape the metal through pushing and pulling (dent tools), or we can remove metal with abrasives (files, sandpaper, buffing equipment). The abrasives are definitely the “path of least resistance,” however, the ideal is to use the reshaping tools as much as possible and to use the abrasive materials as little as possible. In this case, the abrasives were not acceptable options and not used at all; I’ll explain as we go.
The dent was carefully raised from the inside out using standard dent rods and [dent] balls. If the dent were raised too far, it would appear as a bump. Then it would have to be brought back down by “hammering” (more like controlled tapping with various mallets) or burnishing with an iron or roller. This often leaves visible marks.
Since this instrument has a special “vintage” lacquer finish, spot-lacquering over the repaired area was not an option. This also meant that filing, sanding, and buffing were also unavailable options. This, in turn, meant that visible marks were to be avoided, since I had no viable way to remove them. Instead, I pushed up the dented area, gently, many times until the dent was gone, using only the aforementioned dent tools. Then I let the horn rest overnight, because when metal is stretched it tends to spring back towards its former shape. The next day I repeated the procedure, making a few minor corrections. After checking again on the third day, I was satisfied with the result.
Another interesting characteristic of this sax is the rolled tone holes. Some newer horns (Keilwerth, for example), solder a rolled edge onto a straight tone hole. The advantage to this is that the edges are theoretically replaceable if something really bad happens, similar in concept to the soldered tone holes Martin used.
On the P. Mauriat sax, however, the tone holes are fully drawn and rolled like the vintage Conn saxes. Due to this design, they can warp very easily, making pad seating extremely challenging. Sometimes, using partial shims underneath a pad can get the pad to approximately cover the hole but the pad won’t seal for very long. It’s always better to get the tone hole level. On this sax, the low B tone hole needed some serious leveling, possibly a side effect of the bell being dented and then repaired. Standard techniques with the dent tools were used again: bring up the low spots from the inside and/or bring down the high spots from the outside.
Often, the hole is “dressed” with a tone hole file to take up any unevenness that may remain. The objective is to file as little as possible. An impatient or incompetent tech who doesn’t first level the hole using the dent removal techniques can remove far too much metal. In spite of this, he may eventually end up with a level tone hole. However, this is normally considered to be an unacceptable method, since pitch, response, and key alignment can all suffer when too much of the tone hole is removed.
Using a tone hole file, even lightly, on a rolled tone hole is almost NEVER a good idea. Dealing with the tone hole as a series of dented areas (in this case, two areas were pulled up, while one was pushed down) was how I achieved the required result without the aid of a file.