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<DIV>I have no doubt my little experiment is imperfect. I'll have to =
think on
some of the comments I have read and see where, if anywhere, to go with =
this.
And please, if only I could be as eloquent as Howard Rosen's recent =
posts (he
could criticize me and I would thank him profusely with heartfelt tears =
in my
eyes!), I'm not trying to be argumentative in any of this, but rather =
just
trying to understand.</DIV>
<DIV> </DIV>
<DIV>"You need to remember my previous post, where I mentioned that =
there is
some surface fiber swelling. You should also remember my =
suggestions for
testing - drilling the hole with the wood sitting in the shop at 50% RH =
isn't a
good way to measure the change."</DIV>
<DIV> </DIV>
<DIV>The reason I drilled at 50% RH was to reasonably simulate a real =
flange.
Presumably, a flange made in the factory is not drilled at any extreme =
of
RH.</DIV>
<DIV> </DIV>
<DIV>"If carried out properly with a larger change in humidity, the =
drill rod
will become very tight in the center pin holes when the wood is =
dry. Your
test did not change the moisture content in the wood enough for such a =
small
piece of wood to change shape, but it was evidently enough for a slight =
change
in the surface fibers. As I originally suggested, you need to drill the =
hole
when the wood is at one extreme or another, then test the fit when the =
wood has
reached the opposite extreme."<BR><BR>Here again, I can only suggest =
that we are
trying to look at how a real flange would react under real conditions =
(or nearly
so). So, if surface fibers swell with X amount of moisture content =
increase and
make the center pin tighter, would this not mean that the hole gets =
smaller with
increasing RH/moisture content? BUT, I would also say that even going to =
EXTREMES should produce a consistent effect, so your point is well =
taken.
Hmmmmmmm. Some pondering is needed here.</DIV>
<DIV> </DIV>
<DIV>"By the way, a closed container with water inside does not =
necessarily
reach 100% humidity in the air, as you suggested. That would =
depend
on the temperature. Try it with a humidity gauge in there. I =
suspect that
the relative humidity went from your measured ~50% point when you =
drilled the
hole, up to maybe 75% in the closed container."<BR><BR>Oops. I see I am =
as
guilty as you in intermixing use of "humidity" and "relative humidity". =
I
believe, however, it is clear that we are both talking about RH. You =
indicate
your suspicion that "the relative humidity went from your measured ~50% =
point
when you drilled the hole, up to maybe 75% in the closed container". I =
did place
a hygrometer in there and it does go up to 100% RH. That's basic =
chemistry. The
water coming out of solution (evaporating) will reach equilibrium =
with
water vapor in the surrounding air, thus the air will hold as much water =
vapor
as it can at equilibrium, which is the definition of 100% RH.</DIV>
<DIV> </DIV>
<DIV>"With such a small cross section of wood, the amount dimensional =
change is
not enough with such a small change in moisture content."</DIV>
<DIV> </DIV>
<DIV>Again, popular belief is that changes in humidity in real piano
environments can cause real action centers to get tight and/or loose. So =
I want
to see what happens under something close to realistic conditions. An =
argument
could be made that 100% RH is not realistic. True (although I'm sure =
there are
some out there who would argue), but RHs up in the 90%+ range are not =
unheard
of, so I think 100% represents a realistic extreme.</DIV>
<DIV> </DIV>
<DIV>"I have done the exact same test you did with very definitive
results. Try again, but start with the wood either dry or wet - =
not in the
middle. Bake a few flanges in the oven at 250 degrees for and =
hour, then
drill the holes right away when you take them out. Check the fit =
after
drilling, then check them the next day after the flanges reside in your =
wet
chamber for a while."<BR><BR>I'm concerned with the validity of =
introducing such
an extreme of temperature. Clearly, 250 degrees is way out of range of =
anything
normal. How does such an extreme temperature affect the wood? The temp. =
alone
could have an effect of shrinking or expanding wood fibers/cells. Most =
things
expand with increasing temperature (i.e., metal). Perhaps =
your flange hole
was drilled when cells in that area were at an expanded state =
(temperature
perhaps having more an effect than the obvious low moisture content) =
because of
the excessively high temperature, and then when cooled, they shrank, =
causing
the flange hole to be larger. Maybe??? Unless we have some =
kind of
definitive knowledge of extreme temp. effect on wood, I should think =
such an
extreme would invalidate any experiment of the type we are looking =
at.</DIV>
<DIV> </DIV>
<DIV>Terry Farrell<BR>Piano Tuning & Service<BR>Tampa, Florida<BR><A =
href="mailto:mfarrel2@tampabay.rr.com">mfarrel2@tampabay.rr.com</A></DI=
V>
<BLOCKQUOTE
style="BORDER-LEFT: #000000 2px solid; MARGIN-LEFT: 5px; MARGIN-RIGHT: =
0px; PADDING-LEFT: 5px; PADDING-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: =
black"><B>From:</B>
<A href="mailto:DonMannino@mediaone.net" =
title=DonMannino@mediaone.net>Donald
Mannino</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A =
href="mailto:pianotech@ptg.org"
title=pianotech@ptg.org>pianotech@ptg.org</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Sunday, January 14, 2001 =
12:18
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: Results are In! =
Re: moisture
in wool or wood.</DIV>
<DIV><BR></DIV><FONT size=3>At 11:07 AM 1/13/01 -0500, you =
wrote:<BR>
<BLOCKQUOTE class=cite cite type="cite">Good idea Richard. I think =
I will
try that. I have lots of old flanges<BR>laying around. My first =
trial there
was to simply see whether a flange hole<BR>got bigger or smaller =
with
increased humidity/moisture content. It is clear<BR>to me, contrary =
to
apparent popular belief, that a hole in a flange<BR>decreases in =
diameter
with increased humidity/moisture =
content.</BLOCKQUOTE><BR>Terry,<BR><BR>You
need to remember my previous post, where I mentioned that there is =
some
surface fiber swelling. You should also remember my suggestions =
for
testing - drilling the hole with the wood sitting in the shop at 50% =
RH isn't
a good way to measure the change.<BR><BR>If carried out properly with =
a larger
change in humidity, the drill rod will become very tight in the center =
pin
holes when the wood is dry. Your test did not change the =
moisture
content in the wood enough for such a small piece of wood to change =
shape, but
it was evidently enough for a slight change in the surface =
fibers.<BR><BR>As I
originally suggested, you need to drill the hole when the wood is at =
one
extreme or another, then test the fit when the wood has reached the =
opposite
extreme.<BR><BR>By the way, a closed container with water inside does =
not
necessarily reach 100% humidity in the air, as you =
suggested. That
would depend on the temperature. Try it with a humidity gauge in =
there.
I suspect that the relative humidity went from your measured ~50% =
point when
you drilled the hole, up to maybe 75% in the closed container. =
With such
a small cross section of wood, the amount dimensional change is not =
enough
with such a small change in moisture content.<BR><BR>I have done the =
exact
same test you did with very definitive results. Try again, but =
start
with the wood either dry or wet - not in the middle. Bake a few =
flanges
in the oven at 250 degrees for and hour, then drill the holes right =
away when
you take them out. Check the fit after drilling, then check them =
the
next day after the flanges reside in your wet chamber for a =
while.<BR><BR>Don
Mannino RPT<BR><BR></BLOCKQUOTE></FONT></BODY></HTML>