Ventilated rotary valves

Charlie Goodman · Post by **Charlie Goodman** » Sat Feb 26, 2005 7:15 pm

It doesn't seem to be a bad idea.... Miraphone builds them into their pistons on the 1291, I believe. Mine came like that, at least.

chevy68chv · Post by **chevy68chv** » Sat Feb 26, 2005 10:06 pm

Would you guys recommend paying to have your valves vented? I've never played a horn that has had it done, so I'm not really sure how much benefit I would get out of it.

Rick Denney · Post by **Rick Denney** » Sun Feb 27, 2005 12:25 am

Jonathantuba wrote: If it is a good idea, I wonder why don't they make them like that as standard

Not everyone wants it and it's easy to have done.

I recall that TubaRay's Miraphone CC has ventilated rotor casings from the factory, but I don't know if Miraphone did this to other CC 186's predictably. I ventilated the first valve on my BBb 186. I also ventilated the pistons on my Yamaha (at the suggestion of Chuck Daellenbach at a master class), and had Matt Walters do the same for the York Master, mostly so I could dump water without having to contort my other arm around to hold the valve down when I pulled the slide. I haven't vented the valves on the Holton. I don't move the slides on the Holton and I can use the water keys to ventilate the tubes when I pull and dump.

Makes slurs a bit smoother is a definite effect. The YM was noticeably different in that regard after the procedure.

Venting pistons is easier than rotors and I think I spent $40 having four valves done. With pistons, it's a small hole in the piston itself in the port opening for the valve tubing when the piston is up. It vents the valve tubing into the hollow core of the piston, which is of course opened to the bottom of the valve.

Rick "who generally favors vented valves" Denney

tubajoe · Post by **tubajoe** » Sun Feb 27, 2005 12:57 am

Mine are vented on my "vintage" MiraFone 186 CC (last 70's, early 80's.)

To tell you the truth, I dont know if it has a big impact on slurs. It does help if you are a furious slide puller (like I USED to be), but it does slur smoother than Bill Bell's prototype MW CC that I used to play before the Mira.

FWIW

Will · Post by **Will** » Sun Feb 27, 2005 1:00 am

The valves on my 188 were vented. It helped a lot with slide pulls and dumping water out. I went have the valves on my 822F vented and was advised against it. The repair guy said there was more "risk" in venting Yamaha valves. Is this true? I went ahead and had an amado water key fixed on the 1st valve slide which works fine work slide pulls. I hope to soon have the avaiable time and funds to vent the valves on my 1290.

-heads

Rick Denney · Post by **Rick Denney** » Sun Feb 27, 2005 4:15 am

Will wrote:I went have the valves on my 822F vented and was advised against it. The repair guy said there was more "risk" in venting Yamaha valves. Is this true?

I don't know why it would be.

What the technician does is lay the piston in a V-shaped holder and then drill a small hole either with a drill press or a lathe. They usually deburr or counterink the hole and then clean the bits out. That's all there is to it.

Yamaha valves are solid Monel--I don't see what the problem could be.

I vented the valves on my 621 myself. Rather than the risk of drilling, I cut a short slot in the piston using a well-worn Dremel cut-off wheel. The slot runs lengthwise along the piston. I did that at least 13 or 14 years ago without any ill effects since.

Rick "who really can't think of any downside wtih piston valves" Denney

Allen · Post by **Allen** » Sun Feb 27, 2005 7:47 pm

I had the first valve on my rotary horn vented, and also had the first valve slide lapped. It's the only slide I move while playing.

The net result of both of these operations was that I could move the first valve slide easily, and I didn't have to hold down the first valve to prevent air popping.

On this particular horn, I see no need for other venting.

Valve venting is something you do to solve a problem, or to change a horn more to your liking. If you don't have a need, don't worry about it.

Allen Walker

Charlie Goodman · Post by **Charlie Goodman** » Sun Feb 27, 2005 8:46 pm

I actually got a chance to compare vented and non-vented 1291s down at WWBW, and it made a world of difference. The horn opened up and was a lot easier to play.

...... the above is more than likely all in my mind. But the slides pull real nice now!

Mark · Post by **Mark** » Sun Feb 27, 2005 9:08 pm

Rick Denney wrote:Not everyone wants it and it's easy to have done.

...

Why doesn't everyone want it?

Rick Denney · Post by **Rick Denney** » Mon Feb 28, 2005 11:26 am

Mark wrote:
Rick Denney wrote:Not everyone wants it and it's easy to have done.

...
Why doesn't everyone want it?

Not everyone wants to bother with having it done.

I can't think of any harmful effect of venting pistons, but if it doesn't solve a problem then why bother? I have never felt the lack on the Holton, though one of these days I'm going to cut that first valve slide and start moving it a bit. When that happens, I'll need the vents. I hold open the water keys when I pull and dump. The York Master didn't have water keys in the right places for that strategy, and venting the valves made that insturment a lot more convenient to manage.

With a rotary, the vents provide a path for dirt to enter the valves. This is probably why they vented 186 CC's but not 186 BBb's--the latter were mostly used in schools.

Daellenbach showed me the vents on his valves on his Yamaha 621 CC. I cut similar vents on my 621 F as a result. I've never seen him move a slide to improve intonation, but I have seen him pull slides by the handful to dump condensation. I think that's where the vented valves are handiest.

Rick "for whom it is a routine upgrade when the motivation strikes, but probably not needed before then" Denney

TexTuba · Post by **TexTuba** » Mon Feb 28, 2005 12:29 pm

Rick Denney · Post by **Rick Denney** » Mon Feb 28, 2005 12:44 pm

TexTuba wrote:I have a question. What is lapping a slide? I've seen some first valve slides that looked almost polished. Is this a lapped slide? What are the benefits of lapping a slide? What's a ballpark figure for lapping a slide? Thanks for any comments..

If your objective is to make the slide move very easily during play, then there are several issues that have to be dealt with, and in the proper order:

1. The slide tubes (inner and outer) must be absolutely straight and round.

2. The slide tubes (inner and outer) must be perfectly parallel and planar.

3. The inner tube must be small enough so that it doesn't bind against the outer tube.

Most people focus on the third item without even checking the other two. The acceptable tolerance on the first two is perhaps a couple of thousandths of an inch.

If the slide tubes are straight and if they are perfectly aligned, lapping will improve the clearance between the inner and outer tubes to reduce friction.

It would be hard to put a price on this, because in every case I've ever seen, there needed to be some work in the first two items before even reaching the third item.

Rick "who thinks it a mighty fine balance between fast and falling out" Denney