Ergonomics Fixing

[MaryAnn]

Question for you mechanical types.

Say you've got a four-and-a-half-inch wingspan, center to center, between index and pinky fingers, full stretch.

You have fallen in love with a tuba that requires at least that span, and preferably more.

You want to design something that will make that tuba comfortably playble for you. The concept...have a "rotor lever action" for a piston tuba.

I've got one idea but would like to see what other people come up with. I don't care at all what it looks like, only if it works.

Ideas? Do-ability?

MA

[Rick Denney]

You want to design something that will make that tuba comfortably playble for you. The concept...have a "rotor lever action" for a piston tuba.

John Swensen made an extended valve button for the fourth valve on my York Master. It consisted of a plate that slid in a groove, held in place by the screw into the stem. If you put this sort of thing on all four valves, you could angle them in together and reduce the required finger span.

If you want to experiment with the concept, hot-glue pop-sicle sticks on the current valve buttons, extending towards a common center about half an inch beyond the edge of the button. I would think you could narrow the span by at least 3/4".

If the experiment works, I'll send you a closeup photo of my extended button.

Rick "who has big hands but who prefers vertical valve arrangements" Denney

[bigboom]

This iis a picture of what one guy did to do that:

http://www.geocities.com/galvanized.geo ... nders.html

I don't know if this is the kind of thing you had in mind but this way you can even use the same buttons and I don't think it makes the horn look all that different, if that matters to you. Just a possibility, I though it looked kind of like the thing rick was talking about, it just doesn't slide. Good luck and I would like to see pics of whatever you figure out.

Ben

[Rick Denney]

http://www.geocities.com/galvanized.geo ... nders.html

This is Art Hovey's modification. You have to make sure that the button bottoms out properly so that the valve inserts the correct amount, but that shouldn't be a problem. It also maintains the feel of the valve button.

Rick "who thinks these would find a small but devoted market among tuba players if generally available" Denney

[Tabor]

Dr. William Winkle had custom modifications done to the finger buttons of one of his piston tubas. They took mother of pearl stuff from guitars and made long, oval buttons out of some kind of metal and fitted them to his valve stems.

[Dylan King]

You could have something that reaches attached to your hands.

[TubaRay]

MellowSmokeMan's post displays an extremely pleasing ergonomic situation. At least it appears to be so to me. Whew!!!

[MaryAnn]

Weellll.....
I thought that kind of solution will cause you to put other than downward pressure on the piston, which has a tendency to wear the cylinders and cause your pistons to lock up on you.

I was trying to come up with some mechanical solution that allows you to push directly downward on the pistons, not cantilevering onto them, but perhaps the issue is not as big as I thought it is.

MA, who has a friend who had a very "sticky valve" until it was suggested that she try pushing straight down.

[Rick Denney]

Weellll.....
I thought that kind of solution will cause you to put other than downward pressure on the piston, which has a tendency to wear the cylinders and cause your pistons to lock up on you.

Any extra mechanical apparatus is far more likely to cause a problem than an offset button.

From an engineering point of view, an offset button should not put a significant lateral force on the piston. (Since I'm talking to an engineer...) If you push it straight down, the spring would create a moment couple that is the force of depression times the offset. The moment would be restrained by the casing. But the casing will be 5-8 times as long as the offset, which means that the couple resisted by the casing will be 1/5 to 1/8 the couple caused by the offset. This is insignificant.

Now, compare that to the real problem. People put their fingers on the side of the button instead of the center because they can't reach it comfortably, and push on it sideways. If they push on it at a 45-degree angle, the lateral force they are applying is equal to the downward force, which means the casing is resisting a moment couple that is many times what an offset button would cause. Thus, I'll take the offset button over not being able to reach the button any day.

Get the buttons under your fingers and then push them straight down. That will not cause a problem if you provide routine care for your valves (i.e., have them properly fitted and keep them clean and oiled so that you can get away with the minimum of spring force).

Conn short-action valves have always had offset buttons, and some of those are ancient and still work fine.

Rick "who has no problem with offset buttons, properly used" Denney

[Joe Baker]

I tend to agree with Rick about the extenders being okay, but there IS a way to get perfectly straight downward force, and at the same time to get exactly the throw you want.

Check this out:


By changing the location of the pivot point, the lengths of the levers, and the distance from the center of the pulley, you can get whatever throw you want. And by angling them toward the center, the levers can be placed close enough together so that even MaryAnn can reach them.
__________________________
Joe Baker, who thinks this could have application, but would cost a fortune.