Lesson Learned - 4/18/13

I have a recurring problem with flutes that I especially notice when I'm overhauling them. I think I'm pretty careful about leveling tone holes, then making sure pads are perfectly level to the tone holes when I install them. But inevitably I'll level pads, move on to something else, and then go back to double check them and find that they are leaking in the back. By "back," I mean the part of the pad closest to the hinge. I haven't yet figured out why this is, but my suspicion is this: When I install and level the pads, I'm usually doing it with just the spring for that particular key set in its cradle. On the lower stack, for instance, if I'm working on the F pad, I usually won't have the springs set for F#, E, or D. But when I get everything put together and re-check the pad later I'll find that it's open in the back. In fact, I'll usually find that all the lower stack pads are leaking in the back. I suspect this is because the forces exerted on the lower stack by hooking all four springs causes the hinge rod to either bend or rise up from the body, thereby changing the way the pads interface with their tone holes. I tried to experiment with this a little bit today, but didn't see any compelling evidence to support my hypothesis. I'll be playing around with that idea more, though, and hopefully I'll come up with more concrete explanation.