Stuck valve

[Charlie Goodman]

I have a bit of a problem: I can't open my second valve, because the part that screws around the valve button (I've just now realized I have no idea what it's called) is completely stuck. It feels like it's cross-threaded, but it's all the way on, and I don't know if I could cross thread it that far without knowing it, because I didn't have any trouble getting it on.
Anyway, I know quite a few people on this forum are of the technician type, so if you folks have ever experienced this, any help would be great... I kinna need to oil the thing...

[Joe Baker]

To clarify: is the valve itself stuck, or the cap (the part that threads onto the casing, with a hole for the stem to come through). Or both?

I am assuming you are talking about piston valves...
______________________
Joe Baker, who could probably help you screw it up worse, but instead will play to his strength -- getting a clear statement of the problem.

[Charlie Goodman]

The cap. Yeah, sorry, pistons.

[Rick Denney]

I have a bit of a problem: I can't open my second valve, because the part that screws around the valve button (I've just now realized I have no idea what it's called) is completely stuck.

It sounds as though your valve cap is stuck. Technicians loosen stuck valve caps using a small rawhide mallet, striking the knurled edge of the cap a glancing blow in the direction of unscrewing (you know--righty-tighty-lefty-loosey). What happens is that corrosion builds up in the threads and freezes the cap to the casing. If it's a silver tuba, and the threads are plated, the silver-to-silver contact will weld itself together eventually. The light taps with a rawhide mallet (DO NOT consider any kind of metal hammer for this operation) will usually break loose the bond of the corrosion and the cap will come loose.

Ferrees sells the mallet as the F5 Small Rawhide Mallet.

If this scares you in any way, you know what to do: Take it to a qualified repair technician.

DO NOT consider using pliers or strap wrenches or anything like that. Those are much scarier tools in this application than the small mallet.

Rick "who has used his far more often than he expected" Denney

[Dan Schultz]

[quote="Rick Denney"][--righty-tighty-lefty-loosey /quote] ??

[Rick Denney]

--righty-tighty-lefty-loosey

??

I was just (hopefully) eliminating one dangerous possibility.

Rick "thinking a mallet won't help otherwise" Denney

[bigboom]

I am just wondering why it is a bad thing to use pliers for this application. I used pliers on my old school horns, just put some sort of cloth in between the metals so prevent scratching them up. Does using pliers bend the caps? I am just curious because I have since heard this and now use a rubber mallet wrapped with a T-shirt to do it.

I would also like to say thanks to all of the repair techs on this forum, just imagine all the tubas you are saving with all of your tips.

Ben

[Bob Mosso]

pliers ... school horn

I suppose it's possible to not scratch/gouge if you are very careful. This is not a risk most would take on their personal multi-thousand dollar instrument.

[Charlie Goodman]

Curses! I was suspecting my arch rival, lefty-loosey-righty-tighty, might come into play.... ok... one hand makes an L......

[Rick Denney]

I am just wondering why it is a bad thing to use pliers for this application. I used pliers on my old school horns, just put some sort of cloth in between the metals so prevent scratching them up. Does using pliers bend the caps? I am just curious because I have since heard this and now use a rubber mallet wrapped with a T-shirt to do it.
Ben

The problem is that the corrosion will hold under steady pressure pretty well. while a fairly light tap will cause it to crack and crumble. Therefore, you sometimes have to put quite a lot of force into a pair of pliers to break the cap loose, while the mallet blow is hardly enough to make a dent if you miss. The tool that exerts the least force to get the job done is the one I prefer. With all that you have to do to make pliers safe (wood popsicle sticks, as suggested by Art Hovey, on the jaws is one trick that works if you can line up the pliers properly), it's so much eaiser just to reach for the rawhide mallet and give it a couple of light taps.

I would prefer a rawhide mallet to a rubber mallet, by the way, especially if it's wrapped in a T-shirt. The rawhide is light, but it has a harder surface than the rubber and will exert the correct momentum. I would fear that the rubber would absorb too much of its own energy. Rawhide is hard enough to work but soft and light enough not to dent the valve cap.

Rick "not a repair tech but who learned this trick from one" Denney

[Charlie Goodman]

I tried the mallet, and it worked great. Thanks, Rick.

[Dan Schultz]

I am just wondering why it is a bad thing to use pliers for this application.

Even with padding on the pliers jaws, there is still the risk of bending the cap (and the casing) by using too much pressure. I have several horns in my shop right now due to 'student' repairs.

[bigboom]

Sounds like I might need to invest in one of those rawhide mallets, seems it does a decent job of fixing a lot of little problems with tubas.

[Rick Denney]

Sounds like I might need to invest in one of those rawhide mallets, seems it does a decent job of fixing a lot of little problems with tubas.

My wife's uncle came over at Christmas wanting to try out all my tubas. He'd gotten approval to by a new one, and eventually be bought DavidRN's 3301. I asked him if he'd remember his mouthpiece, and he said, "Yes, but..." Because of an eye problem, he used a tuning bit with the mouthpiece on his King, and, sure enough, the mouthpiece was stuck in it.

He asked me if I had a remover, and I said "Yes." But he was skeptical when I pulled out my small rawhide mallet. Five taps on the sides of the bit's receiver later, the mouthpiece was loose. His response? "Nifty."

Rick "thinking this is one of the few tools that can be trusted to boneheads like me" Denney

[MichaelDenney]

Rick Denney wrote:
The problem is that the corrosion will hold under steady pressure pretty well. while a fairly light tap will cause it to crack and crumble.


Very true. Well known to design engineers, at least those of us who have to think of the destructive consequences when a fork lift driver might be distracted by a pretty girl walking across the plant floor, is a book called Roark's Formulas for Stress and Strain. One of his findings was that compared to a steady force, an impact using the same amount of force has fifteen times the effect. So a tap is in a way a multiplier of force and is particularly effective in breaking loose brittle materials like corrosion.