No downbearing ?

[Erwinspiano@aol.com]

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In a message dated 1/2/2004 11:51:20 AM Pacific Standard Time,=20
pianobuilders@olynet.com writes:
I have no doubts that there was some sort drying prior to ribbing but with=20
the uprights a mere few hours of heating isn't really going to take a soundb=
oard=20
panel to an adequately low emc level for compression crowning. None of us=20
would expect that result in our own shops.=20
   I suspect any amount of crown achieved was mostly dependent on=20
circumstance I.E. it was a cold dry time of year & the pre ribbed boards wer=
e already at=20
low emcs.=20
Few of us run soundboard conditioning rooms at anything like the temperature=
s=20
used by these early pianomakers. We certainly don't. You put a batch of=20
already reasonably dry and properly stickered soundboard panels in a room ru=
nning=20
well upwards 120=BA+ and they are going to shrink quite nicely overnight. Al=
l you=20
need to do is get them down to 4%. Standard practice, I'm afraid.

Del
    I wonder if it was common practice to press boards on a flat deck which=20
is what I've always heard.(I forget where) Perhaps no one really knows but e=
ven=20
if they were pressed in a dished caul with ribs that long & usually not very=
=20
tall how much crown could the panel really retain over time. I recently saw=20=
=20
1920 ish Knabe upright with very tall ribs & enough of them. I didn't check=20=
the=20
crown at that time but I will when next I see it. This piano was very well=20
preserved ,great sound. Thanks for the replies.
   Dale

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