Shank Tapers?

[harrisonreed]

What Morse taper # is used for modern leadpipes? Or, more specifically, what morse taper is a large bore shank? I've heard it's a half size, but I don't know what that means - a #2, but not inserted to the full length?

What taper is a small shank piece?

[Doug Elliott]

"Morse Taper" with a number means something specific in the world of machinery. It doesn't mean much in the world of instruments.

A trombone small shank fits within the outer specs of Morse #1. A large shank doesn't.

There's also a series of Jarno Tapers (with a number) which is actually a lot closer to being useful, but those reamers are only available to be custom made.

[harrisonreed]

So a small shank piece taper exists within the length of a Morse 1, but a large shank doesn't match within either a 1 or 2. Thank you!

[hornbuilder]

That's correct. The rate of taper is the same with both small and large shanks though.

[mrdeacon]

When we say taper within this context it's referring to the outside taper of the shank, correct?

[BGuttman]

Outside taper of the shank and inside taper (receiver) of the leadpipe are the same thing.

You could use a Morse #1 reamer to enlarge the receiver end of an old trombone to take modern small shank mouthpieces. If you have a large shank receiver that is a little small there is no commercial reamer that you can buy to fix that.

[harrisonreed]

That's correct. The rate of taper is the same with both small and large shanks though.

So, the taper is equal to a Morse #1 for both? I am seeing that the taper rate for each number in the Morse series varies ever so slightly. And if I was forming the entrance to a leadpipe, a Morse 1 wouldn't go in far enough to fit a large shank. The gague line is less than .5". Wouldn't I go in with a Morse 2, just not all the way (gague line .7")?

I ask because there's gotta be some kind of standard for large shank mouthpiece makers -- .5" at the smallest end of the mouthpiece shank, and a 1.425 degree taper (sort of the average Morse Angle) towards it? If there's a standard, how does a mouthpiece maker or someone like me who wants to do some CAD modelling get the correct outer blank shape in the CAD draft?

Also, it looks like the morse taper is set at a constant rate, but I've seen shanks that appear to have a slight curve in the taper rate -- is that to allow for imperfect leadpipes or milling?

Sorry for the random questions, but there are some seriously smart people here, and I have never thought about any of this before.

[BGuttman]

Older Schilke mouthpieces had a hybrid taper so that they would fit both the standard Morse and the Conn Brown and Sharpe taper. I don't think anybody is doing that any more, including Schilke.

You can easily tell a CAD program to put any taper you want in a design. It may not be in the library of "stock" tapers but there's always the self-specified.

Note that the Morse #1 is a reamer, suitable for making the receiver part of the leadpipe. To run an NC lathe and create the shank you just need to specify the angle and length.

[harrisonreed]

Thanks Bruce. Yeah, if the taper angle is indeed identical to a Morse #1 for either shank, then that's a relatively simple matter, indeed. You would just need to know thr standard smallest diameter that is at the end of the shank to complete it.

I wonder if the angle difference between Morse 1 and 2 even matters -- 1.42xxx vs 1.43xxxx

[JohnL]

FWIW, here are Bach's published specs.

[harrisonreed]

Thanks!! The angle there is about right, 1.43 degrees!