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MMD > Archives > December 1997 > 1997.12.13 > 11Prev  Next

Duo-Art Valve Flow Measurements
By Craig Brougher

Bill Chapman was asking about some way of grading the suede leather
used for valves.  I wonder if anyone else could suggest something about
this? I too have run into all kinds of suede, and not knowing how to
specify it, I just tell people, "Don't use anything that you wouldn't
want to wear with fine clothing."

I also think that Bill will understand what I 'm talking about in
gauging valves with a "blow" test, once he gets hold of a Duo-Art valve
and blows through it (with the stem guide glued to it, of course).  It
doesn't matter if the valve is a cross valve or a round valve.  As long
as you set them this way, you will find an optimum setting, and as you
teach yourself to be sensitive to what you are feeling, you will be
able to set them, go back through once more and check yourself, and
then finish it up, confident that your valves are optimized.

But when you first start testing valves this way, you will have to
recheck yourself more than once, and preferably over a weekend,
sometime.  This way, you make minor (or major) adjustments, you
second-guess yourself enough, and you finally begin to get the hang of
it.  From that point on, that's the way you will do your valves.

The settings Aeolian used were rather careless, I have found as well.
But I have never found any as close as .030.  They have all been easily
over .035, but then again, it's the surface of the leather and the blow
test that is really your criteria.  With paper punchings under soft,
cushy leather, all of which squeezes down a good .010 with a strong
pouch lift, micrometer measurements are moot.

Remember also, that when the valve you have blow-tested is pressed
upward by the pouch, it will give you a bit more gap than the value you
are checking for.  That is why I want to feel a certain resistance,
just above the .035 gap level.

Ultimately, it is experience that will do you the most good.  The first
Duo-Arts you do like this will take longer and may possibly not be
quite as responsive as they will on down the line if you continue to
set them.  But even your first Duo-Art set up this way will beat the
micrometer way of doing it every time, so I can heartily and
confidently recommend it.

Craig Brougher

(Message sent Fri 12 Dec 1997, 19:29:23 GMT, from time zone GMT.)

Key Words in Subject:  Duo-Art, Flow, Measurements, Valve

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