Klarinet Archive - Posting 000012.txt from 1997/04

From: Clark W Fobes <reedman@-----.COM>
Subj: Table concavity on clarinet mouthpieces
Date: Tue, 1 Apr 1997 12:41:32 -0500

I find that a very SLIGHT concavity in the table is helpful in stabilizing the
reed on the
mouthpiece. I agree that too much "dip" in the table may cause the reed to warp
away from the
tip.

My ideal is not to create a pronaunced concavity as to create four firm points
for the reed (or
glass) to rest on.

| A / |
| \_____/ |
| |
| * B * |
| |
| |
| |
| |
| |
| |
| |
| * C * |
|___________|

This is a poor attempt at drawing with a word processor, but I think it will
suffice.

"A" represents the window of the mouthpiece. The rectangular area outlined by
the dashes
represents the table. I attempt to make the concavity no larger than the area
between ponts B
and C. Also, I rarely extend the concave area above point B so as not to create
leakage at the
end of the window.

It is virtually impossible to make a table "perfectly" flat by hand. Everett
Matsen is the
only person I have met who can do this with any accuracy or consistency. The
problem with
attempting a "flat" table is that one inevitably ends up with a slightly convex
or "humped"
table. When this situation exists, reeds behave erratically. (More than usual!)
Some people
describe this as a "warped" mouthpiece. I am not convinced that mouthpieces
actually warp. I
think that over time the mouthpiece facing may lengthen slightly with the wear
of the beating
reed. This causes even greater instability in a mouthpiece that was not flat or
slightly concave
to begin with.

The only way to really test your mouthpiece for flatness (or concavity) is to
use a
standard glass mouthpiece gauge and a .0015 feeler gauge. Place the glass gauge
on the
mouthpiece and hold it firmly with your left thumb. Slip the feeler gauge
between the mouthpiece
and the glass. Slide the feeler down the facing until it stops. While applying a
slight tug on
the feeler in the direction of the tenon end of the mouthpiece, rock your left
thumb forwards
and backwards on the glass. If the mouthpiece is concave there shuold be verly
little if no
movement of the feeler gauge. You may find that the feeler move erratically as
you move your
thumb. This is a very non-flat table and should be corrected

Clark W Fobes