Aligning valve ports

[euphomate]

After installing a complete set of new valve felts in a piston tuba, how can you be sure that the valve ports are lining up correctly with the valve tuning slides? With a trumpet, you can usually shine a light down the slide tubes and check alignment, but how in a tuba with those huge bends at the slide/valve casing interface? I can get a complete view to the first valve through the compensating first valve slide on the Willson 3400 TA-4 with the valve depressed, but how do the techs check the other slides in both the open & closed valve positions? Wish I could see around corners.

[Alex C]

You can buy a small angled mirror like a dental mirror (except that dental mirrors are usually too big) to chekc your alignment. Great hardware stores may have them or find them on the internet. You'll need a light source too.

You can remove second valve, for instance, and check the valve alignment on the first and third valve.

Remove the third valve and check second and fourth.

With the first valve removed you can check the other side of second and the same with fourth, checking the other side of third. Sometime you can check the "other" side of fourth valve from the main tuning slide.

Or... you can buy an optical scope and check your whole tuba but that's a little more expensive.

[Dan Schultz]

Or... you can buy an optical scope and check your whole tuba but that's a little more expensive.

There have been a couple sellers on ebay with bore scopes going relatively cheap. They're cheapo Chinese made ones and don't have top of the line optics, but they do the job we need quite nicely.

There are two kinds of scopes....

1) A fiber-optic scope that consists of a length of bundled optical fibers, an eyepiece, and a built-in light.
2) Full-blown video systems that consist of a small camera and a monitor.

I use a fiber-optic scope with a 30" long reach that works for most things. It can be run down some leadpipes or up through the main tuning slide. It also has an angled mirror so it can be used inside of valve casings. Works pretty good. These are usually in the $300 range. If you have the original pistons in your horn and the stems are all the same length, it's a fair bet that all of the corks and felts are the same. But, it's handy to also have a dental mirror to double-check anything that you can't get to with the bore scope.

The video systems are usually quite a lot more money and require a monitoring system like a computer and special software. There is a camera being advertised for $99 but I've not heard anything good about it in the repairmen circles.

A dental mirror works OK but it's difficult to get the light in the right spot. Some fellows tape a dental mirror to a small flashlight.

The 'old-fashioned' way to check piston alignment is to measure the port location in the casing with an adjustable depth gauge and compare the measurement with the piston port and add the appropriate amount of cork and felts. In some cases, the top caps have a skirt that bottoms out on a ring below the threads and the inside of the cap does not seat directly on top of the piston casing. This case requires adding the difference to the stack height of the corks and felts.

[MikeMason]

Or you can just buy Alan Baer's set and be done forever...

[pulseczar]

Am I ignorant/stupid because I've been using a $15 (OK...maybe $30) dial or digital calipers to do this job?

...Numbers rarely lie...



...Maybe I should send lab mice up in there, and - if they make it through the pistons - I can assume they are properly aligned...


bloke "I keep my Starrett calipers put away, so I won't drop them. "

Please explain the process.

[iiipopes]

And if your tuba is old enough, but still has original valve stems, you align the machined groove in the valve stem with the top of the valve cap. Then you push the valve down all the way without felts or corks in the valve buttons, and blow straight air (not buzzing), adjusting the height of the valve with your finger, until you get the least resistance and/or noise. Then you cork and felt the valve button to that level. That's how it used to be done, before all the gadgets, and how I still do it on the 38K.

When I first got it and took it into a tech to have it done, he used all the fancy instruments, and it came back worse than when I took it in. So I took it in, got my money back, and sat down with him and his cork and felt tray for a half hour and showed him how to do it right.

If you do use traditional/conventional corks & felts, do make sure you allow just the slightest extra bit of thickness for compression and seating in.

[DonnieMac]

Wow! You guys are doing your own root canals, right? Keep it simple and follow this link: http://www.bobreeves.com/services/valve ... gnment.htm" target="_blank
Friday morning I dropped off a Willson 3400 at Reeves' shop in Valencia, CA on our way to TJ, MX. Picked up the horn Sunday on the return trip and learned it was initially from the factory in pretty good valve alignment. Most strokes were about .010" out, up and down. The 4th valve was however .018" out on the downstroke. The alignment service brought all 4 pistons back to .00" both up and down. Did this make a difference? As of right now I can't tell if the horn plays any better but I've thereby lost a crutch on which to fix blame when I play clams. I've had all my piston tubas' valves aligned; Hirs, Nirschl & Boosey. Thus my clams are of my own doing, not the horns'.