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I knew I'd seen this somewhere....

Postby Steve Inman » Thu May 31, 2007 7:45 pm
Another cause for sticky valves -- less likely but frustrating:

Had an annoying problem where my Eb tuba would work fine for about an hour after oiling, then one or two of the valves would start to hang up noticeably.

The experienced repair tech in the next town suggested that if the valve slide(s) had gotten nudged a bit, this could exert some torque on the valve casing(s). After de-soldering and re-soldering a brace or two, everything is working very well...

Perfect summary of the ghosts in my valves. Suddenly last night the valves are running smooth and free, but the instrument doesn't feel as "live" as usual. Checked it over, and find the receiver is no longer soldered to its brace. Time for a visit to the repair shop.

Interesting, that is exactly the problem I had with previous B&S 3181 EEb tuba. I never did find the problem and eventually sold as it was driving me mad sticking without warning 30 minutes into concert.

If you play your horn while holding it in a 'death grip'... enough force might be exerted to distort the valve circuits just enough to cause 'sticky valves'. Some horns are just not braced well enough to be played by The Hulk.

TubaTinker wrote:If you play your horn while holding it in a 'death grip'... enough force might be exerted to distort the valve circuits just enough to cause 'sticky valves'. Some horns are just not braced well enough to be played by The Hulk.

Also... there are a lot of things happening in terms of pressure and temperature that can cause a horn to 'act up'.

First thing I would do is give the valves a thorough cleaning, then switch valve oil. I've been having great luck with Hetman's on the piston horns.

Oddly enough, I have found that some horns seem to be very senstitve to the way the are stored when not played. I have a student that purchased a brand new Jupiter 4 valve comp horn and have issues with the 2nd valve in much the same manner. We tried cleaning, different types of valve oil, etc. Before we tried more invasive solutions (like taking a few thousandths of the FACE of the guide) I suggested that he keep the horn (always in it's case) horizontal, rather than on end. Sure, it took up more floor space, but it kept the oil from flowing to one end of the casing. I had suggested that even though he oiled it every time he played, that the guide channel might be getting dry and ever-so-slightly heating the plastic guide from the face, not the sides, causing it to expand.

I don't know if I'm that smart, of if its just coincidental, but he's been keeping it flat for the past several months, and the problem seems to have magically gone away!

windshieldbug wrote:..... I suggested that he keep the horn (always in it's case) horizontal, rather than on end. Sure, it took up more floor space, but it kept the oil from flowing to one end of the casing. ....

Also... what you have done is prevented all the gunk in the bottom cap of the valve casing from running back over the piston... as it does when a horn is stood on it's bell.

TubaTinker wrote: Also... what you have done is prevented all the gunk in the bottom cap of the valve casing from running back over the piston... as it does when a horn is stood on it's bell.

Interesting. Putting ideas from this thread together, we have:

• Torque on the mouthpipe and/or other tubing distorts the valve casings, making the guides unusually sensitive
• Standing the horn on its bell between pieces allows crud from the bottom cap to migrate into the guide slot and jam the guide.
• Using thicker oil may slow down this backwash (?)
• Adding more oil washes the crud back out of the slot, freeing it up.
• Releasing the torque on the mouthpipe lets the valve casings relax, so the guides are no longer super-sensitive, and everything works ok

Solution(s):

1. fix the torque problem
2. Don't stand the tuba on its bell
3. keep the bottom caps clean

Thanks to all for your input.

tclements wrote:First thing I would do is give the valves a thorough cleaning, then switch valve oil. I've been having great luck with Hetman's on the piston horns.

Agree! That's what I tried. The only thing that reduced (but not fixed) the problem was adding a few drops of medicinal grade mineral oil to the Al Cass: maybe thickening the oil reduced the tendency to flow back ? (maybe you got the same effect by using Hetman's, which I gather is a little thicker ?)

Anyway, the horn has fixed itself now by breaking the receiver loose from its stay.

MikeW wrote:

TubaTinker wrote: Also... what you have done is prevented all the gunk in the bottom cap of the valve casing from running back over the piston... as it does when a horn is stood on it's bell.

Interesting. Putting ideas from this thread together, we have:

• Torque on the mouthpipe and/or other tubing distorts the valve casings, making the guides unusually sensitive
• Standing the horn on its bell between pieces allows crud from the bottom cap to migrate into the guide slot and jam the guide.
• Using thicker oil may slow down this backwash (?)
• Adding more oil washes the crud back out of the slot, freeing it up.
• Releasing the torque on the mouthpipe lets the valve casings relax, so the guides are no longer super-sensitive, and everything works ok

Solution(s):

1. fix the torque problem
2. Don't stand the tuba on its bell
3. keep the bottom caps clean

Thanks to all for your input.

This is all basically true. However... distortion of the ports/valve casings doesn't affect the guides and slots near as much as crud on the pistons.