tuba mouthpieces with threaded rims

[rocksanddirt]

Excellent suggestion! Though the blokepiece seems pretty tightly threaded.

I'm not a big fan of the threaded rim thing anyway, since i don't like to fiddle with mouthpieces a bunch.

I know i've got some teflon in the practice room (garage) somewhere.

[Todd S. Malicoate]

In the auto parts world, teflon tape is generally only used on "pipe" fittings...that is, those in which the male fitting is tapered and the friction of the conjoining threads makes a seal. These are commonly used where gauge senders (and/or computer sensors, sometimes) are screwed into the engine block or intake manifold, and to a lesser degree in the world of industrial/agricultural hydraulic fittings. They are also very common in the household plumbing world. These fittings generally don't "bottom out" and get more difficult to turn as you go.

In "parallel" type fittings such as compression (extremely fine threads) and plain ol' bolts and screws, some sort of "seat" is where the seal is made. On air conditioning and power steering hose fittings these often involve the use of an o-ring. Bolts and screws simply seat when the bottom of the head meets the material it is threaded into. These fittings always "bottom out" when the seat is engaged and don't get more difficult to turn as you go (unless, of course, the threads become damaged). More importantly, these types of fittings don't benefit from the use of teflon tape since the seal isn't made by the threads anyway.

I'm assuming that the threads on a tuba mouthpiece are parallel (not tapered) and that the seal is made where the rim seats against the body of the mouthpiece when fully screwed down. If that assumption is correct and a seal is made at that point, of what benefit is it to fill the (extremely small) voids between the joined threads with teflon tape? As long as the rim is fully engaged to the body of the mouthpiece and "seated," there shouldn't be any air leakage at all.

Todd, who saw a threaded Warburton tuba mouthpiece once but doesn't use one.

[rocksanddirt]

i'd have to look more closely, but it doesn't seem to have a solid 'seat' as you describe. I agree if it did, a thin o-ring or gasket might be the way to go.

[Doug Elliott]

That may be true for the stainless steel pieces you use, but...

I have been making (brass) screw rims for trombone and tuba mouthpieces for 27 years (and a few for trumpet many years ago, but no more). I have always used the same pitch thread for all of them. There is no reason to use different tolerances or fit for different diameters. The same clearance will work equally well at any diameter. And the sealing surfaces are not the threads, so there's no reason to use teflon tape either, unless it's for ease of disassembly. And my threads are a tight enough fit that I don't think there would be room for teflon tape, although I've never tried it.

Teflon tape or thread sealing compound is necessary on tapered threads like pipe threads, under pressure, because the seal is the threads themselves.

[sloan]

I have never had a problem with thread tolerances being loose enough to require tape. If anything, I've had the opposite problem - left screwed together too long, some mouthpieces will "weld" themselves together, requiring some effort to take them apart.

My preference would be for mouthpieces to be built to tighter tolerances than plumbing fixtures - but that's just me.

[Rick Denney]

I have never had a problem with thread tolerances being loose enough to require tape. If anything, I've had the opposite problem - left screwed together too long, some mouthpieces will "weld" themselves together, requiring some effort to take them apart

If they are silver-plated, they will indeed weld themselves together--the silver molecules will migrate across the joint over time. This is how the only wire-wrapped circuit prototypes for early electronic equipment worked, and it worked very well.

For stainless, that should not be a problem. A dab of anti-seize lubricant will make disassembly easy in the future, if necessary. That works for silver connections, too.

Teflon tape can be stretched to an extremely thin film, especially if it's the ultra-thin stuff to start with. But I'd still rather use anti-seize. For stainless steel, the anti-seize should be the silver, nickel-bearing stuff. For brass and silver, it should be the orange copper-bearing stuff. That will help prevent galvanic corrosion.

Rick "a little dab'll do ya" Denney

[Donn]

I'm assuming that the threads on a tuba mouthpiece are parallel (not tapered) and that the seal is made where the rim seats against the body of the mouthpiece when fully screwed down. If that assumption is correct

I'm getting the impression it isn't, for these stainless Hauser fittings? It sounds plausible, but maybe it's hard to make the rim seat that tight, with this material.

[imperialbari]

Is it possible to combine brass parts with stainless steel parts without inviting corrosion?

Klaus

[sloan]

yes. When any of us (even with our HANDS) mess around with steel "stuff" vs. copper or brass "stuff", we know how radically different those substances are. If fine threads cut into brass stuff are barely too snug, they can be schmoozed by various methods...and as you sorta suggest, Donn, the top edge of an underpart of a brass mouthpiece (if the fit wasn't absolutely perfect) could fairly easily be torqued up until it did seat perfectly. (I repair threads all the time on band instruments. As brass - to me - much more resembles mud than it does steel, these thread repairs are usually quick/easy.) When steel threads are barely too snug, any "schmoozing" (without totally re-doing something) could take geometrically more time.

A metal spit valve doesn't fit perfectly (metal-to-metal) against the hole in the tuba...There's a piece of cork or rubber there to allow for the "discrepancy". When I stretch one layer of Teflon tape around the male threads of my steel mouthpiece...and just that (nearly nothing, dimensionally) is enough to completely make the mouthpiece air-tight, (at least) I'm satisfied...and I then use it to play gigs/make money. Yeah, comparing a spit cork to mouthpiece threads might be a bit of a ridiculous stretch, but it still makes the point.

You make a strong case that steel is not a good choice of material for screw-threaded mouthpieces.

[MartyNeilan]

There are high-profile professionals who are already mixing other rims (not of my design) with my underparts...and vise-versa.

Ouch - sounds painful!
You should try and see if this helps:

[imperialbari]

Marty,

Once you receive it, don't leave your mouthpiece sitting around somewhere your spouse will find it...

I wonder where that cartoon stems from. Reminds me of TV commercials in England from 45 years ago.

Klaus

[kingrob76]

That may be true for the stainless steel pieces you use, but...

I have been making (brass) screw rims for trombone and tuba mouthpieces for 27 years (and a few for trumpet many years ago, but no more). I have always used the same pitch thread for all of them. There is no reason to use different tolerances or fit for different diameters. The same clearance will work equally well at any diameter. And the sealing surfaces are not the threads, so there's no reason to use teflon tape either, unless it's for ease of disassembly. And my threads are a tight enough fit that I don't think there would be room for teflon tape, although I've never tried it.

Teflon tape or thread sealing compound is necessary on tapered threads like pipe threads, under pressure, because the seal is the threads themselves.

Doug, Cindy called and said get off the computer get back to work Glad to see you're back doing fabrication (mouthpieces, not houses)

[Todd S. Malicoate]

When any of us (even with our HANDS) mess around with steel "stuff" vs. copper or brass "stuff", we know how radically different those substances are. If fine threads cut into brass stuff are barely too snug, they can be schmoozed by various methods...and as you sorta suggest, Donn, the top edge of an underpart of a brass mouthpiece (if the fit wasn't absolutely perfect) could fairly easily be torqued up until it did seat perfectly. (I repair threads all the time on band instruments. As brass - to me - much more resembles mud than it does steel, these thread repairs are usually quick/easy.) When steel threads are barely too snug, any "schmoozing" (without totally re-doing something) could take geometrically more time.

Agreed. Stainless steel is not something widely used in any of the fittings I described earlier, and certainly would behave radically differently than the material used in those.

In any event...a thin, inexpensive strip of teflon tape applied in the way Bloke described may be of some benefit and CERTAINLY wouldn't hurt anything.

Todd, conceding the point.

[sloan]

In any event...a thin, inexpensive strip of teflon tape applied in the way Bloke described may be of some benefit and CERTAINLY wouldn't hurt anything.

Todd, conceding the point.

Would heavier lead tape be useful to improve the tone?

[imperialbari]

In any event...a thin, inexpensive strip of teflon tape applied in the way Bloke described may be of some benefit and CERTAINLY wouldn't hurt anything.

Todd, conceding the point.

Would heavier lead tape be useful to improve the tone?

Yes, if you swallow it.

K

[jonesbrass]

That may be true for the stainless steel pieces you use, but...

I have been making (brass) screw rims for trombone and tuba mouthpieces for 27 years (and a few for trumpet many years ago, but no more). I have always used the same pitch thread for all of them. There is no reason to use different tolerances or fit for different diameters. The same clearance will work equally well at any diameter. And the sealing surfaces are not the threads, so there's no reason to use teflon tape either, unless it's for ease of disassembly. And my threads are a tight enough fit that I don't think there would be room for teflon tape, although I've never tried it.

Teflon tape or thread sealing compound is necessary on tapered threads like pipe threads, under pressure, because the seal is the threads themselves.

I currently use three makes of screw-rim mouthpieces: Doug Elliott, Loud, and Warburton. I have never had any problem with blow-by or seepage in any of them.

[sloan]

In any event...a thin, inexpensive strip of teflon tape applied in the way Bloke described may be of some benefit and CERTAINLY wouldn't hurt anything.

Todd, conceding the point.

Would heavier lead tape be useful to improve the tone?

Yes, if you swallow it.

K

Tuba players have swallowed a lot when it comes to new, improved methods of producing a good tone.

[imperialbari]

bloke "who hopes - somewhere in this thread - I did not inadvertently type the word 'underpants'...whoops, ' just did! "

After all you are preferable with rather than without. At least in a tuba, and in a seeping, context.

[rocksanddirt]

bloke "who hopes - somewhere in this thread - I did not inadvertently type the word 'underpants'...whoops, ' just did! "

After all you are preferable with rather than without. At least in a tuba, and in a seeping, context.

I think.....