Posted by art on August 30, 2000 at 23:40:16:
In Reply to: Venting Piston Valves posted by Rick Denney on August 25, 2000 at 16:47:02:
I have been venting pistons since 1962, when I thought of it for myself. It's such a simple idea that I am sure that other people figured it out too, but I never saw anything about it in print until ten years later. I first did it to an old baritone horn with a hand-cranked twist drill, not electric. Since then I have used an electric drill. I have never had a mishap, nor have I ever seen any flaking or corrosion problems as a result. The dremel tool sounds like an excellent idea. Naturally you have to be careful; try it first on a junk horn to get the feel of the operation. Just be careful not to squeeze the piston out of shape, and de-burr the edge of the hole carefully. There is no way it can affect the sound of the instrument, because there is never any contact between the hole and the vibrating air in the instrument. I think there are two reasons why manufacturers don't do it: First, it's an extra step that only a few buyers would care about. Second, the "tightness" of a piston is sometimes a selling point. If you pull the slide and then depress the piston and hear a resonant "pop" you can use that as part of a sales pitch about close tolerances and fine craftsmanship. It's similar to the sound of a car door slamming in the showroom. Does that satisfying thunk really mean it's a good car?
After you drill that vent hole the valve is just as tight but you can't demonstrate it so easily to the prospective buyer. (Then you have to be able to play music, instead of making funny noises!)