Rotary valve maintenance/questions

[bort]

I know this has been discussed at length here, but I can't seem to find the old threads I've been looking for.

I have a few questions about rotary valves, and how they get seated and aligned in the casing. Forgive me, I don't know all of the right names for the parts. Also, I know that obviously, the best way to see if it's aligned is with a bore scope, but I don't have one.

-- When you unscrew the back caps of the valves, there are some etched in alignment marks, presumably made by the person who built that part of the tuba. One pair is on the backplate/casing, the other is on the backplate and the part that spins. Is it possible that these are NOT always entirely accurate? So if the valve appears correct through the bore scope, the alignment of the markings is not relevant? On my RM, some of the markings are pretty far off between the backplate/casing, but the other set of marks looks okay.

-- Should the backplate be flush with the casing? Or does that vary as well? On my RM, some of the backplates/casings are completely flush. On others, the backplate is about 1 mm "higher" than the casing. Is that normal?

My intuition tells me that the markings probably aren't totally accurate, but some of the valves might not be seated properly...? Can post pictures if that helps.

The other caveat to this -- this is all for my own education, and I have no real desire to disassemble and mess with the rotary valves myself. And when I get my tuba into the shop to repair the bell, I will, of course, have it thoroughly checked out to make sure nothing else needs attention.

[bort]

Ok, pictures to follow in the next posts...the main questions are:
-- Is this normal, or out of whack?
-- If it's out of whack, is it like the rotor equivalent of needing a piston valve alignment?

Maybe it's just something that needs to be adjusted, maybe it's fine as-is... all these years playing rotary tubas, and I haven't really paid attention. Seems like a good time to learn. So, what's the word?

Thanks!

[bort]

These are both photos of the 4th valve. The "X" is not aligned, and the plate seems to be out of place.

WP_20140425_003.jpg

WP_20140425_004.jpg

[bort]

These are both of the 3rd valve. The markings aren't lined up, and the cap isn't flush.

WP_20140425_005.jpg

WP_20140425_007.jpg

[bort]

One more... this is the first valve. Markings on the outside are not aligned, neither is the spindle(?) in the middle. But on this one, the valve cap is flush.

WP_20140425_010.jpg

WP_20140425_011.jpg

[bort]

So what happens when the bearing plate is out of alignment? Does the rotor itself become misaligned or become allowed to move in ways it shouldn't? I think there was a video about taking apart/reassembling rotors somewhere, but I couldn't find it.

[bort]

Thanks Joe... actually, I just spent a little while watching Jeff Funderburk's videos (which is was I was looking for), and I think it has the answers I need:

http://www.youtube.com/watch?v=Z4FiyDzwoaA" target="_blank

Seems like a reasonable project to try... why not? Might still give you a call if things go awry.

[bort]

Cool... well, time to buy a hammer and bang the valves out of there!

But seriously, are you implying it's not really all that hard? Seems like something good to learn. (I know, pick up the phone...)

[tofu]

Bloke is imply he is lonely and wants you to call him on the telephone.

Bloke the lonely RM repairman waiting for bort to call.

[bort]

Ok, getting a little weird here, guys...

[eupher61]

It's almost as easy as picking up the phone to call bloke.

Jeff's videos are great. There are 2 school of thought about replacing the back plate. One is Jeff's, to use a block with a cutout for the bearing plate. The other is to use the back cover, screw it down tight, tap it to seat a bit, repeat until properly seated.

I've been chastized by some here for using the cover method, but I've seen plenty of repair techs do it that way. And, plenty with the block too.
It's really a matter of getting the plate tight enough, and straight enough. that the valve is snug in place, without top to bottom wiggle, and that the cover doesn't cause it to seize. If it DOES seize, the plate isn't in right. Most of the time. Other things could cause the seizing.

Do yourself a favor...call bloke. He's offering his advice. he knows of what he speaks. And he probably won't charge more than $9.99 for the phone horn dorn.

[pjv]

Really,
I always hammered on the back plate with a small dowel; tick tick on the left, tick tick on the right, then the top, then the bottom, cross-wise, whatever until it seats. And if you hit it just one time too many then flip the horn around and tap the valve once or twice from the other side. If the valve has no lateral movement yet spins freely, eh, when spun, it should be OK.

[Phil Dawson]

Call Bloke!!!!!!!! He's great to talk to and has a wealth of great information and he's fun too. I've talked to him several times and always found that I learned things, Phil

[JCalkin]

I use a neatly and evenly cut length of pvc pipe to seat bearing plates. The pipe fits around the raised part of the plate allowing me to strike the plate in the center, as opposed to "wiggling" it in by going around and around with a dowel, and the pvc is long enough that i'm not in any danger of clumsily hitting the tuba with a misplaced hammer blow.

[Lee Stofer]

I will offer my $0.02 on the matter.

If one assembles the right tools and uses due caution, after being shown once how to properly disassemble, clean, lube and reassemble a rotary valve, it is little more than a routine task.

Wm. Bruce Maples, who got his bachelor's degreee at Tennessee Tech, once had the entire tuba studio at Western KY University over to his apartment one evening while he was a grad. assistant at Western. Armed with a Mirafone 186 and a Mirafone tool kit, he proceeded to show us exactly how to clean and service the rotors. I must have been the only one excited by the prospect, for I was soon the "go-to" guy for rotor valve problems for the rest of the studio.

The mis-aligned rotor back caps in your photos only show the bearings to be mis-aligned, not necessarily the valves themselves. If the back bearing plate is not aligned correctly when it is installed, that just throws off the markings in the center, making it difficult to know what you have for alignment.

All Rudolf Meinl and Alexander valves I've worked on, and many others were designed to have the back bearing plate tapped in until it stops. Bearings for older Meinl-Weston rotors, and some of the Chinese rotors which are copies of old Meinl-Weston rotors, will lock up the rotor if the bearing is tapped in as far as possible. In that case, I try to get it as level as possible, install the back cap and then loosen it about 1/8 turn, then turn the instrument over and tap straight down on the rotor stem (gently, using a rawhide mallet, NOT a hammer), until the rotor turns freely. On older, funky rotors that may have been damaged, if the rotor turns freely through the range of movement with the stop arm on, it doesn't have to turn freely 360 degrees, although it is nice if it will.

If the valve bearings are in reasonably good shape, and you clean the rotor and rotor casing well, oil liberally and reassemble the rotor and bearing cap, everything should be OK. I would strongly advise AGAINST tapping on the back cap, as the back cap threads are easily-enough damaged without adding to their stress. I use a piece of plastic clarinet body, about 6" long, which gives plenty of tapping room away from the body of the horn, and a good flat surface on the bottom to help with good alignment. That way, I don't generally have to do "a tap-tap here, a tap-tap there"., etc., but just center the clarinet-body tool over the center hole of the valve and tap it in evenly. The same thing could be done with a junker clarinet barrel (or a good one). Once you have the rotor and back cap in place and turning smoothly, turn your attention to the stop arms and bumper plates. I put the best-quality neoprene material into the bumper plates, then check and check again as I trim the bumpers to get the proper alignment. Accuracy is important here, as just a little variation can play havoc with the intonation and response of an otherwise-good horn. And, if you have the alignment marks aligned right between the valve casing and back bearing, then you can trust the rotor shaft-to-back bearing markings. I received a perfectly-wonderful Alex 163 in for servicing last year that had all of the back bearings installed off to one side, and hence had been "aligned" all wrong by someone, and the instrument was hideous. In less than 4 hours, it was fully-serviced and played like the champion that it is.

If anyone has questions or concerns about Rudolf Meinl rotary valves, they are a specialty of mine, and I would be delighted to offer assistance.