Venting Pistons -- Is the Tuba required?

[Worth]

Would the valves only suffice if I wanted to pack them carefully and ship them?

I'd like to get this done and know there are some very reputable people on this forum who can do this rather easily.

This seems a great option if not familiar with expertise of local technicians. The only question is whether it is necessary to have the Tuba with valve block present at the time of the work. Thoughts?

[tbonesullivan]

Theoretically, no, but the person doing the work would need to know where the ports are located when the valve is in the up position. If it is a newer instrument, or has stainless steel pistons, that can be hard to see on the piston body itself.

Also,without the valve block, they can't check to make sure that there is no drag on the piston wall after the venting procedure.

[Worth]

Thanks tbone. Valves are stainless and 1,2,3 have the stained outline present in the proper area for drilling. I'm not concerned about drag after venting. I'd rather deal with that myself than take a chance with a local unknown or worse yet, ship the horn just to do this. That's why I've been holding off. I think it would be pretty clear with the proper photos and valve port outlines to go by. I bet there are others with this same question.

[roweenie]

If the pistons have "ghost marks", you might get away with it.

As usual, Matt has the answers:


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Personally, I wouldn't chance it without the horn present, but that's just me.

[Art Hovey]

Anyone who is reasonably competent with tools can vent a piston if you first explain to him or her exactly what needs to be done and what mistakes need to be avoided. (You don't want the drill to go in too far, you don't want the piston to roll around, and you don't want it to be scratched or deformed in any way.) Try it first with a piston from an old, less-valuable but still playable instrument, perhaps a baritone horn, just to get the feeling. I would consider that approach much safer than shipping my pistons to someone else, because things do sometimes get lost and damaged in transit.

[Worth]

Thanks Roweenie and Art very much. I'll dig back through the archives and edumacate myself further before proceeding. I'm not a repair tech, but my day job has involved considerable technical savvy under magnification (dentistry) and I enjoy bonding with my horns through working on them. I have the materials to construct a jig and understand holes, bur sizes, countersinks, slots, off-center, higher, not to deep, etc. I'm thinking a proper jig and a dental handpiece with the piston well protected and secured in a holding device of some sort. My main reservation was the hardness of the stainless valves and them "rolling around" with unwanted surface scarring. I do have some throw away pistons from, yes a dead old Cleveland baritone, to practice on, an excellent suggestion. I agree, shipping the pistons introduces yet another variable to be avoided if possible. Thanks again to all.

[Charlie C Chowder]

I apparently do not understand what is done when venting a valve. And probably not the purpose is either. I thought it was to help with the slide pulling by removing the vacuum and pressure caused by the pushing and pull of a slide for tuning correction. And therefore a hole was drilled in the valve casing, not the valve itself.

Charlie C. Chowder

[tbonesullivan]

I apparently do not understand what is done when venting a valve. And probably not the purpose is either. I thought it was to help with the slide pulling by removing the vacuum and pressure caused by the pushing and pull of a slide for tuning correction. And therefore a hole was drilled in the valve casing, not the valve itself.

Charlie C. Chowder

With piston valves, they are hollow inside and not sealed, so it's easier to put the vent into the piston than the casing.

With rotary valves, they are usually solid, so they can't really be vented in that way. There are some rotor designs however that are "internally vented", such as the rotors that Yamaha uses on most of their Xeno trombones.

In both cases, the venting is felt by some to make slurs a bit smoother sounding.