Cross Threaded Piston Valve caps.

[Rev Rob]

Have any of you ever had to work with piston valve caps that someone (maybe yourself) cross threaded and ruined the threads?

My 2341 King has very fine threaded valve caps. I quickly realized they could easily be cross threaded if I was not paying attention. I am very careful when re-assembling my valves after oiling them.

[Dan Schultz]

Yes.... valve caps can easily be cross-threaded. It's a good rule NEVER to apply more than light finger pressure when reassembling the caps.

If you have a cap that's particularly unruly... get a new one and have your tech make sure the threads on the casing haven't been damaged.

[Rev Rob]

Thanks for the advice Tubatinker and Elephant. Since I can't stand sticky valves, I am getting quite experienced with properly starting my valve caps.

[iiipopes]

What elephant said. The 38K has a valve cap with worn threads. I was in a hurry to get oiled right before a parade gig, and as I put it back on I scuffed it and it stuck. After a moment of panic, I regrouped and asked the snare drummer for his stick. He looked at me funny but handed it over. I gently tapped the cap with one hand as I rotated with the other, and it finally popped over one thread and came off. I then rethreaded it carefully back on straight literally as the parade marshall gave us the cue. Whew!

[djwesp]

I'm sure that this is technically wrong, and someone will call me out on it, but I have a routine I use to insure I do not cross thread.

I just push the piston down with normal pressure, then with the pressure on the valve button I rotate the valve cap the opposite direction until I hear a click. Then I let the pressure off of the valve button and then is just spins right on.

I played on a very bad panamerican sousa that was horrible at this and that's where I learned this technique, it has served me well on sousas and my 983.

It also doesn't hurt to put a little slide grease on that thread, too. It is a lot easier to determine the actual thread alignment because it turns so much easier.

[gwwilk]

I'm sure that this is technically wrong, and someone will call me out on it, but I have a routine I use to insure I do not cross thread.

I just push the piston down with normal pressure, then with the pressure on the valve button I rotate the valve cap the opposite direction until I hear a click. Then I let the pressure off of the valve button and then is just spins right on.

I played on a very bad panamerican sousa that was horrible at this and that's where I learned this technique, it has served me well on sousas and my 983.

It also doesn't hurt to put a little slide grease on that thread, too. It is a lot easier to determine the actual thread alignment because it turns so much easier.

What he said. This technique, i.e. backing off the threads until you feel/hear the thread head line up with the groove while maintaining proper alignment of the parts, is useful in starting any threaded fastener. I have a 12" threaded lid on my pet food container that is almost impossible to tighten without backing it off first. When oiling the bottom bearing of my rotary valved tubas, I always use this technique screw on the bottom cap. It's a natural thing to do.

[Dan Schultz]

I find it difficult to concentrate on mundane tasks. Screwing valve caps back on to a tuba is a mundane task.

Over the years, I've developed an unconscious routine of turning them backwards until they "click" (indicating thread alignment). At that point, I begin rotating the other direction and screwing them into place.

Ditto. I figured EVERYONE already knew this and it wasn't worth mentioning. Some of the things we take for granted are often overlooked.

[Rick F]

Over the years, I've developed an unconscious routine of turning them backwards until they "click" (indicating thread alignment). At that point, I begin rotating the other direction and screwing them into place.

I thought everyone learned learned this when they were a kid from their mom or dad? Like when closing a jar of pickles or whatever.

[tubaforce]

Hello! I am paying to fix the casing on 1st.Valve of my "beater" Yamaha 321 Tuba! I had the horn loaned out, and the borrower did me a "favor" and payed to have it cleaned! Not only did the cap end up cross threaded, but I have some "new" casing issues being addressed too! Lesson learned, don't let anyone ya don't know/trust do anything to your horn! I usually oil my pistons by inverting them, and oiling from the bottom.I only remove the caps once a month or so. But when I do, I wiggle the cap gently, and test that first 1/4 turn carefully! I would be cautious of greasing the threads, as it could make it easier to start 'em wrong in the heat of battle. I do drop a little bit of valve oil on the threads that once a month or so, and do the same on my rotors every time I apply rotor oil to them! I do that at least every month, and use a mix of piston and rotor oil one the bearings in the intervals! Al.

[tubaforce]

Hello again! Thank Heaven I am within 100 miles of A Master Craftsman(Dan Oberloh)! I have a particulary advantageous(to me!) trade worked out for the 321, and I'm gonna execute that deal as soon as Dan says the horn's ready! If my 13y/o were a big burly boy rather than a slender girl, I would keep the thing and let her have it! It does have a great sound for Concert Band, but Yamaha should have copied another model when they made this Besson-esque clone! Al.