Posted by Chuck(G) on February 24, 2003 at 14:10:12:
In Reply to: Re: Re: A question of physics posted by Rick Denney on February 24, 2003 at 12:28:12:
It's probably a matter of gilding the lily.
One could make rotary valves with user-replaceable oiltite journal bearings and manufacture the rotor axle from steel rather than soft brass or perhaps use jeweled bearings. Were replacement parts to be widely available, I suspect that this discussion wouldn't even come up. Probably the same reason we don't see chain or rack-and-pinion driven rotary valves--there's just no material gain to be had. However, the bottom-cap adjustment screw on Miraphone rotaries does function as sort of a thrust bearing, doesn't it?
One of the boutique flute makers uses tiny roller bearings in the action on his instruments. He argues that the perpendicular force on a rod is significant owing to the pressure from the player's fingers. As far as I know, he's the only one to do this.