Posted by Rick Denney on April 09, 2002 at 17:54:19:
In Reply to: Question about modifying rotary valves posted by Dave on April 09, 2002 at 14:33:34:
There is nothing inherently wrong with this plan, but heed the warnings:
1. If you bend or distort the valve, it is junk.
2. If you poke a hole into the port, it might as well be junk--the repair will be a pain in the butt.
Both of these mistakes seem quite easy to make in such a project.
Cerveny, at least at one time, made hollow rotors, with ports made from curved brass tubing, soldered into a shell, similar to piston valves. I had one such instrument (it was marked "Sanders") and the valves were really quick. But it doesn't seem like the Easy Way. They don't do this anymore, or at least not on all instruments--Jay Bertolet talks of scooping out the ports on the valves of his 601 which would be impossible with hollow rotors.
Check and make sure it isn't the linkage or the rotor shafts that are slowing things down.
In short, if you are a qualified machinist with a lathe or a mill and the skill to use it, then gord ahead. If you are contemplating doing this with a power drill, run away quickly. I'm tempted to suggest that if you needed to ask the question, then, well, you get the idea.
Rick "who can ruin almost anything with a power drill" Denney