Tuba with bulged casings?

[Donn]

"Whys and wherefores" are worth thinking about, though. Sure, a valve case is much stronger than your slide tubing, but it's also dealing with more water. Water apparently expands by 9% on freezing. It's conceivable that the gap between your inner and outer slide was an order of magnitude thinner than the gap between piston and casing in an old, worn out tuba. I submit that the question is not whether various parts of the tuba are strong enough to prevent ice from expanding -- I think we know the ice will win -- but whether the effect will be significant. I don't think it will in any case - still much less than 1/1000 inch per freeze/thaw cycle - but who knows.

The question has been burning in my mind since it was brought up, wreaking havoc on one's tuba by pulling the slide without opening the valve that is, and while pulling my valve to dump water just this afternoon, some vague memory returned to me about drawing gunk from the gunk passage into the bearing surfaces. Maybe that's why I go to the trouble to push the button while I pull the valve?

[Three Valves]

In my opinion, a picture of the outside of a valve casing, for the sake of discussion on an internet bulletin board, is not something that calls for obsessive attention to repeatable accuracy.

Are you new here??

[Dan Schultz]

I would gamble nobody is quite sure how or why valves and casings wear how they do because there are too many variables. Let's leave this thread for archives and accept they wear down in interesting ways and give thanks to the skilled technicians who restore them.

I agree. I tend to just shrug my shoulders... fix stuff... and chalk the 'whys and wherefores' up to '**** HAPPENS'.

Do you want to talk about spring dynamics for a while? How about the virtues of torsion springs, constant velocity springs, and coil springs? Or why a piston key clicks and clacks against the sides of a guide slot? Wanna hear about how to eliminate springs altogether by using air or magnets?

Maybe string rotors VS. spherical ball ends?

'The gap' hasn't been discussed for a while!

[Tabor]

bloke wrote:
- Pistons could theoretically be fairly straight and fit into the top of the casings fairly snugly...but the valvecasings could be shaped like a typical tuba player (puffed outward about halfway down - where all of the ports are located.

Explain?

Some music store owner buys some of these for the (certified repair guild member) genius in the back room.

bloke "There's nothing that f's up stuff better than 'tools'."

Hey..those things are so popular that they sold out and were on backorder until about a month ago. Now they are all stocked up. They are probably in a lot of back rooms and band rooms out there.

[saxophyte]

I have had tubas and sousaphones bought from schools that have had unbelievable things done to them.One 20k had the #2 casing spread open by an exhaust pipe expander to open it so the piston would fit .If fit with about a 1/16 inch of play all around .I also had a yamaha ybb321 that had dents in the valve casings and was repaired by ramming a dent ball through the casings by a well meaning parent.Another sousa was FIXED buy using a brake piston hone on the casings .

[PaulMaybery]

Okay! Okay! I posted the issue of "ice," and in certain cases it does weald a significant force. I posted this simply as an alternative theory. A theory. Some very wise tubneteers who I have awesome respect for (Tinker, Doug and Bloke) have added their opinions. Tubatinker Dan, even tried an ice experiment, that if any effects transpired, were hardly measurable. Bloke suggested my main suspicion all along that a tool, a tube expansion tool was likely the culprit in an over zealous 'backroom' attempt to free a binding valve. I will confess in my early days as a "know it all repair idiot" that I did used that procedure to attempt to 're-round' a compromised trumpet casing. The results were just as the OP had described. "A bulged valve casing" Am I going to Hell for that miscreant behavior? I think not. I made good on my project and replaced the entire valve casing to the delight of the owner. As Bloke alluded earlier this issue, it sure has been taken "seriously". I rather enjoy the collegium of experts (TNFJ) and the insight they provide. As Tubeteers we are privileged to enjoy such a consortium of brain power (lest I offend someone).
Perhaps as Bloke has suggested in another post that we should convene in a cornfield in Nebraska for some reconnoitering. (Oops!!! The cornfield is my idea.)

[Dan Schultz]

Okay! Okay! I posted the issue of "ice," and in certain cases it does weald a significant force. ...

Hey! ... you had me thinking enough about the ice theory to at least give it a test! I rather liked the concept.

[PaulMaybery]

Dan, your 'the man' when it comes to sorting things out. I was almost going to go into more elaborate theories about the inherent strength of the piston owing to "compression." (here we go again - lol) The expansion force from the ice is working it's radial forces inward, similar to a roman arch. The material has little or no place to go. On the other hand, the pressure against the casing is in a outward direction for which there is little restraint other than the integrity of the brass itself. I'm also not sure if the temperature has anything to do with the power, hardness and make up of the ice. Here in Minnesota it is realistic to have temps around 40 below (actually temperature) Having spent 10 years with the good old Salvation Army at Christmas kettles, we would often dash from within a warm store and make a valiant attempt to get through the 16 bars of "Jingle Bells" one time, before valve seizure. The larger horns usually froze up first and cornets last. On days when it was 20 below, even that was optimistic. But I do concede and agree that the expanded or bulged casing was likely due to a tool.

[Rick Denney]

If the casing was filled with water, and not just wet between the piston and the casing, the ice theory becomes interesting.

I love the attachment of "well-meaning" to parents trying to repair instruments using the same methods as the local muffler shop. Personally, I rather doubt their motivations, whatever their intentions. My bet is they were trying to keep from losing their deposit.

It's a common strategy to make something bigger when what it needs is to be made straighter.

Rick "who can think of lots of honing situations where this is true" Denney

[PaulMaybery]

This is better than HBO and Netflix.

[Dan Schultz]

This is better than HBO and Netflix.

You betcha! I don't have HBO or Netflix. I prefer to spend my entertainment money co-sponsoring TubeNet! This kind of humor is easily worth a couple of movies a month. Eh?