Valve Venting Explanation requested

[MN_TimTuba]

All,
I've seen a number of photos of vented piston valves here, and quite a few of you have done this to your horns. I've not seen an explanation of the specific benefit, though. Please enlighten me.
Thank you in advance.
Tim

[Dan Schultz]

Venting simply connects the valve circuit to atmosphere while the valve is at rest. This allows you to pull the slide on that circuit without generating the 'pop' in your face when you press the valve down.

On pistons a hole is drilled in the piston in the proper location.

On rotors a hole is drilled in the casing in the proper location.

[Rick F]

Dan's explanation is right of course. Another way to explain it is the small vent hole lines up opposite the bottom leg of the valve's slide when the valve is at rest - or in the up position. When the valve is up you can pull that coresponding slide (in preparation to tune that fingering) without hearing a pop when you DO press the valve down. The vent hole is covered up by the valve's casing when the valve is depressed so there is no leak. Also helps when playing slurred passages so you don't hear as much popping during temperature changes as the horn warms up.

[MN_TimTuba]

Rick and Dan,
Thank you both for the explanation! Now I understand, and - judging by the many views of my question before you answered - I believe you may have helped some others as well. Nice work.
Tim

[Steve Marcus]

Why don't manufacturers vent the valves?

[windshieldbug]

Why don't manufacturers vent the valves?

My 1970's Mirafone came that way; it's just more work that some regard as not worth the cost.
If you've never been bothered by the "pop" or don't pull slides you'd likely not notice it...

[Dan Schultz]

Why don't manufacturers vent the valves?

The Miraphone 1291 5V BBb I owned until I bought my 5/4 Rudy came from the factory with all four pistons vented.

I vented only the first valve on the Rudy.

Personally... I'm glad manufacturers DON'T routinely vent valves. Venting valves is a great way to cover up poorly fit valves. ... sort of like having loud mufflers on automobiles.

[arpthark]

The issue I have with rotors being vented is that I oil the back bearing by pulling the slide to draw oil into the bearing. With vented rotors, you can't do that

Cover up the vent hole with your finger?

[bort]

Meh, nobody actually does that anyway.

[bort]

My observation has generally been that piston tuba players do more slide gymnastics than rotary tuba players. Perhaps that's not totally true or accurate, but it's what I have observed.Well, actually, what I observe more often is that people don't pull any slides, ever, and just blame the tuba for being out of tune. Maybe its just that the more serious players I have known all play piston tubas, and care about intonation?

With rotary tubas, vented valves supposedly help make slurs between notes clearer. They are also necessary for tuning slide kickers.

I have owned vented and unvented tubas, both piston and rotary. I didn't really notice much of a difference either way. Whatever it was, it was fine that way, and I had no desire to change it.

[opus37]

There are instances where piston tubas tend to "pop" a bit while with unvented valves. I believe its when folks are pulling slides for tuning. In those instances, you may want to consider venting the valves.