Question concerning rotary valve linkage modifications

[Rick Denney]

OK, enough with the Illustrator vs. Corel Draw monkey business - time to push some pixels!!!

Heh, heh, a man after my own heart.

I'm with Bloke. This isn't enough offset to worry about linkages with the bends you show. I was thinking you were going with much more offset extending down the valve stack.

Rick "who thinks designs are more clear when really drawn to scale" Denney

[ThomasDodd]

Looks like all you guys are missing the obvious solution - hydraulic linkages. Clearly superior to the old-fashioned mechanical linkages used for tuba valves because of tradition.

I'm with Doug here. But forget compressors.

Just put a large piston on the paddle, so the size of a penny, and a small piston(1/3 the diametrer) to push a pin at the rotor. Force multiplication With a big enough difference we cold reduce the paddle trave to that of a clarinet key, and have heavy spring on the valves. Then we could play all those fast runs the WW get:)

We could even use clear tubing for a cool look

Man I wish I had a lathe to work this out... Little cylinders and pistons aren't easy to find

[Art Hovey]

The action of the pushrod on the ball-and-socket joint on a rotary valve is similar to the action of a foot pushing down on a bicycle pedal. But with a bike pedal you can bend your ankle and use your leg muscles to push forward as well as downward at the top of the stroke. The rotary valve mechanism does not have that extra feature. The pushrod can only push along the imaginary line connecting the balljoints at its two ends. (This is still true even if the pushrod is bent or curved.) In normal operation the rotor is at roughly 45 degrees from “top dead centerâ€

[Dan Schultz]

Looks like all you guys are missing the obvious solution - hydraulic linkages. Clearly superior to the old-fashioned mechanical linkages used for tuba valves because of tradition.

.... I'm with Doug here. But forget compressors.....
We could even use clear tubing for a cool look

Man I wish I had a lathe to work this out... Little cylinders and pistons aren't easy to find

I used to use hydraulic linkages on everything from racing boats to dune buggys. I've been thinking about doing this on a tuba for some time but other projects have taken front seat. You don't need a lathe. There are plenty of miniature components on the market that would work. And yes... the whole thing could be plumbed up with clear tubing if you wish. It's really simple. Just a cylinder at each end with vinyl tubing between. With a little practice you should still be able to do anything you oridinarily do. You don't need messy fluids. Air will work just fine. You can find the stuff here:

http://www.tecopneumatic.com/line.htm#Actuators

[Chuck(G)]

Just put a large piston on the paddle, so the size of a penny, and a small piston(1/3 the diametrer) to push a pin at the rotor. Force multiplication With a big enough difference we cold reduce the paddle trave to that of a clarinet key, and have heavy spring on the valves. Then we could play all those fast runs the WW get:)

We could even use clear tubing for a cool look

Man I wish I had a lathe to work this out... Little cylinders and pistons aren't easy to find

There's always solenoids and switches...

Actually, a hydraulic rotary actuator might be better suited than a cylinder to the valve end. There are plenty of sources for either in submini sizes, but they're pretty pricey in small quantities...

Sprocket and chain is another possibility. Direct and efficient--and easier to find at reasonable prices.

[Dan Schultz]

Sprocket and chain is another possibility. Direct and efficient--and easier to find at reasonable prices.

Lessee... sprocket & chain?? string?? sounds familiar

How about flexible cables... direct drive.

[ThomasDodd]

There's always solenoids and switches...

Lets keep electronics out/off of the brass instruments

Actually, a hydraulic rotary actuator might be better suited than a cylinder to the valve end. There are plenty of sources for either in submini sizes, but they're pretty pricey in small quantities...

For a new design, rotary sounds ggood. For retwofitting though a linear actuator driving the old arm would be simpler to add, I think.

Dan, If air would work fine, but colored liquids would be more interesting looking. Even a clear oil in a clear tube looks more interesting than air in the same tube.

I like the idea of short paddle throws and fast valve changes. Not sure sprockets and chains would be as effecient either.

[Dan Schultz]

Dan, If air would work fine, but colored liquids would be more interesting looking. Even a clear oil in a clear tube looks more interesting than air in the same tube.

I'm just thinking about the potential for leaks. I have pneumatic switches on my hot tub controls and if they ever become sluggish, it's just a matter of unplugging one end and allowing atmospheric pressure to reenter the system.

Hey! on the other hand... I think you might be on to something here.... Fill the system with rotor oil with a little food coloring added. And... equip each circuit with a tee and a small needle valve to meter oil to the rotor bearings. Viola! A maintenance-free tuba

[Chuck(G)]

Lets keep electronics out/off of the brass instruments

Awww, spoilsport

How about clear tubing with this stuff threaded inside and blinking at about MM=168?

[ThomasDodd]

How about clear tubing with this stuff threaded inside and blinking at about MM=168?

If it would glow longer that an hour or two sure.

Maybe you could use electronics for the lighting. What happens if an optical fiber end in a tube filled filled with clear oil? Shouldn't the oil glow? Then you could use a rotating wheel and cycle the colors too.

[Chuck(G)]

If it would glow longer that an hour or two sure.

Maybe you could use electronics for the lighting. What happens if an optical fiber end in a tube filled filled with clear oil? Shouldn't the oil glow? Then you could use a rotating wheel and cycle the colors too.

Of course, that goes without saying! That's why yoiu also need one of these:



'course you could just pop open that sucker and let the neutron flux directly excite the phosphors in the EL wire...

[Chriss2760]

The tuba valves of the new millenium are solenoid operated. Silent, fast as an atom, and only minor maintenance. (The SOVs I live with function 24/7 for years and problems are rare.) 12VDC power, lightweight battery pack, (think modern bicycle lights), I don't see any problem, other than having to get used to the idea of a truly electric horn. I'm not advocating it, just saying it is easily do-able, right now.

[ThomasDodd]

If it would glow longer that an hour or two sure.

Maybe you could use electronics for the lighting. What happens if an optical fiber end in a tube filled filled with clear oil? Shouldn't the oil glow? Then you could use a rotating wheel and cycle the colors too.

Of course, that goes without saying! That's why yoiu also need one of these:

[[batery picture]

How much would that sucker cost. Still, could be a fun conversation piece.
Do they still make them, or was it just a '70s experiment.