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<DIV>Tuesday, January 2, I started my hole in wood experiment to see if =
a hole
will get smaller in diameter or larger with increased humidity. Rather =
than
drilling holes in wood that may or may not reflect what happens with an =
actual
flange, I took three old flanges lying around my shop. One was an grand =
damper
flange, one an upright hammer butt flange, and one was a grand hammer =
shank
flange. All were likely in the 40 to 80 year old range, and all had =
been
sitting in my shop in 40% to 50% reletive humidity (RH) for months. I =
drilled
out the flange bushings with a 1/8" drill in my drill press, being sure =
to keep
things square. I cut three pieces of 1/8" drill rod for center pins. I =
filed the
ends and polished the rod/pins so that they were nice and smooth. All =
three
rods/pins fit into the flanges real easy by hand, but had no slop. My =
pinky
could easily push them in and out with little effort.</DIV>
<DIV> </DIV>
<DIV>Since Tuesday the flanges have been sitting on a little plasitc =
platform in
a tupperware box with a little water in the base. The flanges have not =
touched
the water, but rather have been exposed to 100% humidity for three days. =
The
center pin for the damper flange fits noticeably tighter, but was no =
trouble
pulling it out with fingers. The butt flange was tighter yet. And the =
grand
hammer shank flange was very tight, I could just barely push it in and =
get it
back out - VERY tight.</DIV>
<DIV> </DIV>
<DIV>It would appear to me that the hole in a wooden flange decreases in =
diameter with increasing humidity. Am I wrong? </DIV>
<DIV> </DIV>
<DIV>I'm gonna wait a whole week and then check them again. After that I =
will
dry them out real good and slow and check them under very dry =
conditions.</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> Monday, January 01, 2001 =
10:56
PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: moisture in wool =
or
wood.</DIV>
<DIV><BR></DIV><FONT size=3>Terry Farrell wrote:<BR>
<BLOCKQUOTE class=cite cite type="cite">I have heard/read this =
many times,
so I suppose it is true. But, intuitively, it makes no sense to me. =
If you
drill a hole in a piece of wood and expose it to high humidity, the =
wood
will swell - and swell much more across the grain (perpendicular to =
the
grain direction) than with the grain. So why doesn't the hole tend =
to close
a bit - on the two sides of the whole where the tangents are =
parallel to the
wood grain.</FONT></BLOCKQUOTE><BR>Because the whole piece of wood =
swells, and
the hole becomes larger along with the piece of wood. As I wrote =
in my
last post, imagine the plug of wood which used to be in the =
hole. The
hole behaves the same as the plug of wood that was taken =
out.<BR><BR><FONT
size=3>Do the hole and rod test. Just pick a small piece =
of maple
or something, soak it in water for a while, then drill a hole in =
it with
a spare drill. After drilling, put the drill back in the hole, =
then dry
the wood in the oven! That drill will be really nasty tight in =
the
hole! You'll have to soak the wood again to get it =
out.<BR><BR>There are
some exceptions to this behavior:<BR>1. In some situations the surface =
fiber
swelling in the hole exceeds the change in shape of the wood. =
Key
balance holes are examples of this, where high humidity sometimes =
tightens the
fit. The wood thickness is small, and the wood fibers are large =
and
sometimes made of more reactive wood.<BR>2. Cross-laminated wood is =
more
dimensionally stable, and the surface fibers will again have more =
affect on
the hole size than the dimensional changes of the wood. This is =
what
happens in pinblocks.<BR>3. If the hole was made by compression of the =
fibers
instead of by drilling and removing wood (like with a nail) then the =
grip on
the nail is tighter during humid times. All surface fiber =
effect, no
hole to swell.<BR><BR>Don Mannino =
RPT<BR><BR></BLOCKQUOTE></FONT></BODY></HTML>