Klarinet Archive - Posting 000310.txt from 1999/09

From: LeliaLoban@-----.com
Subj: [kl] Key metals (was [kl] Clarinet Disassembly)
Date: Sat, 11 Sep 1999 20:31:03 -0400

Michael wrote,
>A second question was foreshadowed by Lelia Loban in a separate post today.
It concerns the temper of the metal keys which have already been slightly
bent in the past, and heated and reset by the technician on each occasion. To
what extent does successive heating and bending of the keywork, interfere
with the temper of the metal and cause it to soften so as to cause the
keywork to be more susceptible to bending under pressure? >

Bill Hausmann wrote,
>>I believe if the keys are heated first, the temper is unaffected, or
relatively unaffected. But the real experts will correct me if I am wrong, I
am sure.>>

I'm no expert (yeeeeowie, don't I know it!), but I agree with Bill Hausmann
that heating the keys is a good idea. Heating greatly reduces the
possibility of the key breaking during bending. However, when the key is
heated, it's also crucial to anneal the metal properly afterwards, by cooling
it at the right rate. Otherwise, it can actually end up more brittle than it
was before heating. Glass, for instance, must be cooled from the malleable
stage over a period of hours in a kiln: taken down very slowly, then held in
the annealing zone, then taken down the rest of the way slowly, or else the
finished glass will crack if you look at it funny. Good bronze, however, is
best tempered by plunging it from above the annealing zone straight into
tepid water. (Ancient Roman makers of bronze swords used to swear by
tempering them in the urine of a red-headed boy! -- I would think that
anybody downwind would swear AT this method!)

For more specific information, see _Henley's Formulas for Home and Workshop_
(edited by Gardner D. Hiscox, M.E., first edition 1907, revised 1927). My
809-page edition (Avenel, 1979), contains more than 10,000 formulas. IMHO,
anyone interested in a practical shop reference manual without too much
advanced chemistry should have this big book. I got this edition remaindered
at Crown Books for US $7.99 about 15 years ago. There's at least one more
recent edition. Modern editions often turn up used.

Henley's includes much information about annealing and tempering procedures.
Under the heading, "Alloys", Henley's lists 6 main formulas and 21 additional
named formulas just for German silver, along with more than two dozen
different formulas for brass for casting, forging and sheets, some with
warnings that they're brittle and others listed as ductile. The best way to
handle brass depends on what's in it. It may contain small amounts of lead
and tin along with the copper and zinc; and the proportions of copper and
zinc vary a lot, from about 73% copper down to about 64% copper. "White
brass" is less than 50% copper, down to 10%!

Although I know the metals typically used in stained glass work, the
instrument repair technician will have far better information than I have on
what specific alloys musical instrument manufacturers use now and used in the
past, and how best to handle them. Henley's lists more than 50 formulas for
various types of white metal (pot metal), for instance, so to anyone who
wants to know exactly what's really in those old B&H Edgeware or Conn
Director keys, lotsa luck. The instrument factories may not even have known
the formulas used by the foundries that supplied them (and may not have
received what they thought they ordered, a whole 'nother story).

But a list of formulas on paper and a clarinet key in the hand are different
things. At my beginner stage of learning to repair wind instruments, my
personal rule for bending keys is: Don't! I take that kind of work to my
repair guy, who learned what he's doing based on years of experience with the
instruments themselves. Okay, I'm lying. Sometimes I bend a key. But only
on a cheap "learner" clarinet.

Lelia

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