moisture in wool or wood.

[Farrell]

This is a multi-part message in MIME format.

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"I think what Dan is trying to describe to you is simply that if the =
"hole" wasnt there... then what would happen to the same area of wood =
around that hole ? Why should that react differently, or why shouldnt it =
? Think about that as well when you drill your test piece tommorrow. :) =
"

Keeping in mind that I am simply trying to understand and make sense of =
this, my reasoning is as follows: If the hole was not there, that area =
of the hole would expand and get larger, just as he indicated. AND, if =
the hole is not there, then wood is there, and wood expands with =
increasing moisture content, causing the area in which it resides to get =
bigger. BUT if there is a hole there, then there is no wood there, and =
the wood around the hole will expand, thus closing off the hole (or at =
least moving in that direction). So, yes, it should react differently, =
because a hole reacts differently than wood, and wood next to a hole =
will be able to expand/contract in a different manner than wood next to =
wood. And I will think about all of that while I drill my hole. I might =
even drill two holes. I might even drill several holes of different =
sizes. So there!

AND I will also be thinking about what a pleasure it is to interact with =
other technicians on topic such as these to gain better understandings =
of our work. This is the kind of thing that when we keep to ourselves in =
a little cocoon, errant thoughts will remain and perhaps multiply =
indefinitely. Of course I know that sometimes we don't solve a darn =
thing and only generate more fodder for argument, ah, er, I mean great =
discussion. Thanks for all the input. I'll report back with results!

Terry Farrell
Piano Tuning & Service
Tampa, Florida
mfarrel2@tampabay.rr.com
  ----- Original Message -----=20
  From: Richard Brekne=20
  To: pianotech@ptg.org=20
  Sent: Tuesday, January 02, 2001 2:45 AM
  Subject: Re: moisture in wool or wood.


  I think what Dan is trying to describe to you is simply that if the =
"hole" wasnt there... then what would happen to the same area of wood =
around that hole ? Why should that react differently, or why shouldnt it =
? Think about that as well when you drill your test piece tommorrow. :)=20
  In returning a bit to the starting point for this thread, it seems we =
have reached a consensus that this problem about keybeds and lost motion =
is probably more related to felt being affected by humidity changes then =
to wood related concerns ??=20
   =20
   =20

  Farrell wrote:=20

    Your position is consistent with many others. It is likely I who is =
hard/thick headed. I just may go out to the shop tomorrow morning and =
drill me a hole in some maple and see what happens. Just does not make =
sense to me.  :-)  I'll report back! Terry Farrell=20
    Piano Tuning & Service=20
    Tampa, Florida=20
    mfarrel2@tampabay.rr.com=20
      ----- Original Message -----
      From: Donald Mannino
      To: pianotech@ptg.org
      Sent: Monday, January 01, 2001 10:56 PM
      Subject: Re: moisture in wool or wood.
       Terry Farrell wrote:=20
        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.

      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.=20

      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.=20

      There are some exceptions to this behavior:=20
      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.=20
      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.=20
      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.=20

      Don Mannino RPT=20
      =20

  --=20
  Richard Brekne=20
  RPT, N.P.T.F.=20
  Bergen, Norway=20
  mailto:Richard.Brekne@grieg.uib.no=20
   =20


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