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There is a good guide to rotary valve maintenance at this link at Osmun Music.

For the rotors themselves, you can drop rotor oil straight down the second valve slides and then rotate the instrument to reach the other valves. How much? several drops, enough to wash away corrosion debris; if you use too little the instrument will tell you.

David Schwartz wrote:There is a good guide to rotary valve maintenance at this link at Osmun Music.

For the rotors themselves, you can drop rotor oil straight down the second valve slides and then rotate the instrument to reach the other valves. How much? several drops, enough to wash away corrosion debris; if you use too little the instrument will tell you.

And if you use too much, it will simply drain away when you open the water key.

Roger Lewis has some great advice as to oils:
1) 3-in-1 oil for the linkage to keep it quiet.
2) Singer sewing machine oil for the rotor bearings (including taking the bottom cap off periodically and filling the little "well" in the cap that will keep the bearings operating freely.
3) Any good valve oil for direct application to the rotors to help "seal" the rotor for playing and wash out any gunk, like dissolved slide grease creeping into the bearings.

This is what I do.

The manner of applying a couple of drops of valve oil directly down the slides to the rotor casings is an issue of debate, whether down the leadpipe and/or through each individual valve slide. I've done it both ways and I can't tell any difference in my valve action. So, I keep the leadpipe clean and dry, and pull the 1st valve slide, drip 3 drops down the center of the upper tube, so as to not let it come in contact with the vertical tubing so it doesn't dilute slide lubricant. And since my 2nd rotor seems a bit worn (1971), after that I turn the horn on its side and do the same thing to the 2nd valve slide, again careful to hold it upright and steady so that the oil drips directly onto the rotor. I replace the valve slides without depressing the valves so the oil is forced around the rotor somewhat. This seems to help the intonation on my worn rotors by eliminating "leaks."

Remember that unlike pistons, rotors ideally never touch the casings as they are suspended in the bearings. But if these bearings become worn, you can get wear on the rotors. Since the rotors never ideally touch the casings, a film of oil is necessary to complete the "seal" on the valves.

I tried putting a little valve oil down the leadpipe every day, as suggested by a reputable tuba guru. After about a year I found a lot of gray sludge in my leadpipe, working its way into the pistons and gumming them up. Apparently the oil and the water from my breath were combining in some way to make a mess. I have doubts about the effectiveness of valve oil to prevent leadpipe corrosion, and I know that the sludge problem was a royal pain.

My favourite way of oiling the inside of the rotors is to stand the tuba on its bell, pull out the main tuning slide and then drip oil down the centre of the tube while moving the rotors. Then replace the slide, upright the tuba and blow while still moving the rotors, so any surplus oil which passed through the valves will go back through to coat the other side. Finishing by draining surplus oil via main water key. This method however only really works for tubas with vertical main tuning slide (as are most of mine).

Every two, or three months I will wash through through the inside of the rotors with hand hot soapy water to get rid of any loose particle inside (such as bits of food). I will similarly do this by turning on bell, pull out main tuning slide, to put in funnel to pore water from jug. Once again moving the valves. I will also snake the leadpipe at the same time and it is amazing what gunk often comes out. One jug of water suffices. Then I pull all slides and empty. Leave the slides out overnight to let the inside dry, re-oil using method above and put all back together.

The rotor bearings and linkage I will usually oil about once a month.

dgpretzel wrote:Thank you all for your comments.

My horn has arrived, and so far I'm quite pleased with the St. Pete 202N. But then again, I'm not a professional.

So, now I have a few follow-up questions.

First, regarding oiling the rotors by introducing oil down the slides... The second valve is clear enough-- a few drops down the middle of the tubing. But, all the others have one or more 90's (the fourth valve circuit has at least 360 degrees in the aggregate, and the thirdd has a 270 all in one place) and substantial tubing to get from the removed slide to the actual valve. So, I can't just drop oil down the center of the tubing and into the valve.

1) Do I just use more oil, and do the spin thing to get the oil to it's destination? Do I add oil until I detect surplus coming out the spit valve?

You can. It's really not necessary. Enough oil usually gets there from when you oil #1 and #2.

dgpretzel wrote:2) How do I get the "other side" of the valves covered?

See the answer to #1.

dgpretzel wrote: would like to oil the lead pipe for corrosion prevention, but am leary of the risk of sustained breathing of petroleum distillates. I am using a synthetic (Hetman's), but isn't that still carbon chains (of uniform length)?

It's valve oil. So long as you don't drink a quart of it, it's a non-issue. And you're better off for corrosion prevention by making sure you brush your teeth and rinse your mouth before playing rather than anything else, then once every so often have the #1 rotor popped out and snake the leadpipe.

dgpretzel wrote:3) What is a good safe (assuming that petroleum or synthetic is risky to have in close proximity to mouth and breathing) oil for dowsing the leadpipe? I guess it should be something that doesn't cause any problem with the Hetman's that I want to use to directly target the rotors. It would be really nice if it didn't have a strong [petroleum] odor. Perhaps one of the "flavored" Zaja products?

If you must, Roche-Thomas is clear, colorless, and about as tasteless and odorless as it gets. And a 16-oz bottle is not that much more expensive than a 1-oz bottle of a "boutique" brand of valve oil. I've used it for over 35 years.

Remember, rotors are made to sit in the rotor spindle bearings and theoretically at least don't touch the sides of the casings as do pistons. So all of this discussion about applying oil to the rotors is actually the secondary discussion. FIRST, remember to keep the little wells in the bottom caps filled with something like Singer sewing machine oil, and the top rotor spindles well lubricated also.

dgpretzel wrote:Thank you

Regards,

DG

You're Welcome.