Most modern instruments have drawn tone holes. These are the kind you see where the tone hole is formed from the body of the instrument and there is no seam. When the body of the instrument is made it has small holes punched out of the metal. Then a specific diameter metal ball is then drawn up through the hole which widens it and forms the tone hole.
Another technique is to cut the appropriate diameter hole and then place a separate metal ring which forms the wall of the tone hole on the body of the instrument. The wall is soldered to the body of the instrument.
The advantage of soldered tone holes over drawn tone holes is their superior ability to hold their shape and not warp because of dents or over time as the metal relaxes. The disadvantage is that on very old instruments, the solder can disintegrate causing leaks.
Pictured above is a soldered tone hole on a Conn bass saxophone I was working on. You can see a massive space has formed between the body of the instrument and the wall of the tone hole. To repair this we simply re-solder the tone hole to the body, filling in the gap.
Although the procedure is simple, usually where there is one un-soldered tone hole there are others and fixing this requires many keys to be removed. An inexperienced repair person my not notice these problems when they estimate the repair job. That’s why it is important to always estimate carefully and use a leak light.
Being that I have the fortune (or misfortune depending on the day) of living and working right outside of Philadelphia, I’ve worked on more bass saxophones in a few years than most repair people will in a career. The Mummers are a big deal in Philadelphia and boy do they love their saxophones. The Mummers parade is on New Years day and is basically a bunch of men dressed up in feathers and sequins dancing down the street stone drunk. Somewhere in that mess are a few string bands, also drunk and dressed all fancy. These guys are a tad rough with their horns and the bass saxes the have are pretty much all in the century old category. So when they come into the shop, they are in really bad shape.
This one (the one on the chair in the picture) has soldered tone holes. Let me tell you, this sax has been a nightmare. Pretty much every tone hole has big gaps where the soldered has crumbled away between the body and the tone hole. How the horn played a single note at this point is beyond explanation. So yesterday I was going around every tone hole and filling in all the missing solder. Today I started replacing most of the pads; the horn really needs an overhaul but the band doesn’t want to shell out the cash so I was told to ‘make it play’. Thankfully I’m doing this bass at my full time job instead of at my shop so the couple of days this work is taking me isn’t on my dime. I expect to finish the job tomorrow by lunch time and I’ll be glad to be finished with this one.
So if you have a saxophone, a Martin for instance, with soldered on tone holes and you have a mysterious leak that you just can’t seem to pin down, there’s a good chance that the solder joint between the tone hole and the body has a leak somewhere. Make sure your repair checks when you bring your horn in, especially if it’s a vintage horn.