Posted by Klaus on September 18, 2001 at 13:04:00:
In Reply to: Re: Re: Re: Re: Re: Re: Thayers on tubas.... posted by Chuck(G) on September 18, 2001 at 11:29:57:
No disclaimers are called for, as this is not a matter of war between slide-lurs and conical garbage grinders. Maybe with the tiny modification that tubas traditionally are expected to be a bit more agile than trombones.
It is a matter of physics and technical productions, areas where you should beat me by default. Still this:
My understanding is that the speed of valves is a matter of two factors.
Weight of the moving parts (inertia and momentum considerations).
The area of the bearing surfaces (considerations of mechanical resistances modifiable by lubrication).
Milled rotors are massive, hence relative heavyweights. I yet have to see my first milled piston. Milled pistons for compensating tubas would require spring tensions incompatible with even the most macho finger strengths.
Paxman used to be considered very inventive in French horn designs, if not always the best executors of these designs. They were front riders on the triple descant horns with triple slide layers calling for quite long rotors. To counteract the ill effects of too heavy rotors, these rotors were hollow with soldered-on air pathways.
Rotors only should bear on their end spindles. No contact between rotor and the wall of the casing is desired, but can happen when lime and oil residues gum up on surfaces.
My suggestion went for a long, hollow piston-look-alike rotor riding only on its end bearings. My preferred material would be stainless steel. I would be prepared to consider a split trigger action applied on both ends of the rotor to counteract the ill effects (of a torsion nature), that might come into play on a very long rotor.
Have I been cryptical? You bet! But somehow my ideas might come trough to you, though.
Klaus