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Threading mouthpieces for screw rims

Posted: Wed Apr 19, 2017 3:02 pm
by ttf_Doug Elliott
There are potential unforeseen issues when threading other mouthpieces for my screw rims...

I'm working on one now, and I've seen this before:

What appears to be a one-piece mouthpiece isn't one piece - the rim has been pressed on.
I think this particular one will come out OK, but it might not.
This is from one of the well known manufacturers.

Another one I've seen:  It's a bit if a surprise to start cutting into a mouthpiece and find that it's nickel-silver, not brass.

Threading mouthpieces for screw rims

Posted: Wed Apr 19, 2017 3:20 pm
by ttf_TromboneMonkey
I suppose those are cost-saving measures?  A company can make hundreds of cups and press on the different rims? 

Seems legit...  Image

Threading mouthpieces for screw rims

Posted: Wed Apr 19, 2017 3:51 pm
by ttf_BGuttman
I have a couple of very old mouthpieces (~100 years old) that have pressed rims.  One is not completely pressed on and has a sharp corner in it that I can feel.  I don't use them much since I only have two horns that use them (neither of which I play much) and I have other two part mouthpieces that are properly aligned.

Making a rim and pressing it on a mouthpiece saves material over carving it from a solid cylinder.

Doug, is it much different to machine nickel silver versus 342 brass?  (342 has a little lead in it and that makes machining easier.  Most of the mouthpieces I have tested were that form of brass.  Another reason to make sure the plating is intact.)

Threading mouthpieces for screw rims

Posted: Wed Apr 19, 2017 4:03 pm
by ttf_Doug Elliott
I'm just mentioning it because I don't want to be responsible for ruining a mouthpiece that I couldn't have known would be a problem.

Nickel silver cuts a little differently from brass.

Standard brass rod is currently 360, not 342

Threading mouthpieces for screw rims

Posted: Wed Apr 19, 2017 4:31 pm
by ttf_BGuttman
With the RoHS requirements, 342 would no longer be allowed in anything that touches your mouth.

I didn't test any mouthpieces that were post-RoHS.  Now I can't because I'm no longer employed at that lab.

Threading mouthpieces for screw rims

Posted: Wed Apr 19, 2017 5:46 pm
by ttf_Doug Elliott
360 has lead in it too

Threading mouthpieces for screw rims

Posted: Wed Apr 19, 2017 5:46 pm
by ttf_Doug Elliott
360 has lead in it too