Klarinet Archive - Posting 000034.txt from 2007/08

From: X-BakerBotts-MailScanner-tom.henson@-----.com
Subj: RE: [kl] Wood as a "living" material and Barrels for Selmer and Rossi clarinets
Date: Wed, 08 Aug 2007 18:28:48 -0400

Hi Clark,

Thank you for explaining this process in more exact terms than my rubber
band explanation. Obviously this was only an allegory that I used to
explain about the tension in wood as you work it and the change that
takes place afterwards as it relaxes.

I would also be curious if the heat generated during the machining
process has any effect on how precise the wood will hold the
measurements as the tension is released. Walter Grabner explained that
some heat is given off by the machining process and I saw smoke coming
from some body blanks at Morrie Backun's shop as they showed us how they
machine the tone holes. Granted, it was a small amount of smoke only as
the bit first hit the wood, but the heat was enough to generate smoke. I
think in this example they were using Cocobolo wood instead of black
wood if that makes any difference. Does the wood expand at all during
the machining process due to the heat generated, and if so, how does
this effect the final tolerances as the wood cools back down?

I also think that the sharpness of the bit or reamer being used is a
factor in how much heat is generated. I have seen some barrel tenons
from a French maker (big 3) that actually showed signs of chattering
with a rough surface and minute chips in the machined surface. Not sure
if this is indicative of poor quality wood, very dull machine bits or
both.

Clark, you also mention that you machine your barrel blanks many months
in advance to minimize the changes in the wood. While I can say that I
have seen most of the major makers pre-drill the body blanks for this
same reason, I do not remember seeing them pre-drill the barrel and bell
blanks. Part of what I was trying to convey (and perhaps not well) was
how fast the wood was worked and what effect it had on the final
dimensions as the wood went back to it's relaxed state. You seem to be
saying something to the effect that working the wood over time is better
at minimizing the changes and that is really the heart of what I was
trying to say.

Wurlitzer may indeed be obsessed in that they pre-drill the blanks, age
them over an extended period of time, then when they put the blanks into
production they still machine them slowly over a period of days. Even
then, the finished bore of their clarinets is still somewhat undersized
to allow a final polishing & sealing of the bore during the first
overhaul several years after being put into use. The fact that the
clarinet must also be retuned tells me that they are taking off enough
material during this process to require it to be retuned. I can not
attest to whether all this effort they go to is worth it as I have yet
to have my first overhaul done, only that they do it.

It sounds like you are very quality conscious about your barrels and I
only wish I owned a French clarinet so that I could try one. If they are
anything like your mouthpieces, they are very good indeed.

Tom Henson

<< Clark Fobes said:=20

In the case of African=20
Blackwood we can hold very fine tolerances as we machine material.
Within a=20
few days the wood will begin to change with the grain as some of the
tension=20
within the wood has been released. This apparently occurs even with wood

that is well aged. A perfectly concentric tenon becomes ovoid or "egg"=20
shaped after just a few days. The more material that is removed at one
time=20
the effect becomes more pronounced.

To counter this phenomenon we machine our barrel blanks many months
to=20
a year ahead of the finish date. The raw blanks are bored through and
then=20
tenons are rough bored to 0.020" under the finish dimension. Over 6
months=20
to a year these blanks with continue to dry and change. This slow,
natural=20
process allows the wood to relax and change about as much as is
possible.=20
Once the barrel is machined from this state we can measure very little=20
change in the following weeks or months. Generally, the barrels sit
another=20
3 to 6 months before I make the final hand ream, play test and then ship

them. >>

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