No downbearing ?

[Farrell]

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"I recently saw  1920 ish Knabe upright with very tall ribs & enough of =
them. I didn't check the crown at that time but I will when next I see =
it."

I kept a rib from an 1890s Knabe upright that I disposed of. I couldn't =
find it just now, but I know it had quite a bit of crown in it - clearly =
in excess of a 60-foot radius.

Terry Farrell
  ----- Original Message -----=20
  From: Erwinspiano@aol.com=20
  To: pianotech@ptg.org=20
  Sent: Friday, January 02, 2004 5:20 PM
  Subject: Re: No downbearing ?


  In a message dated 1/2/2004 11:51:20 AM Pacific Standard Time, =
pianobuilders@olynet.com writes:
      I have no doubts that there was some sort drying prior to ribbing =
but with the uprights a mere few hours of heating isn't really going to =
take a soundboard panel to an adequately low emc level for compression =
crowning. None of us would expect that result in our own shops.=20
         I suspect any amount of crown achieved was mostly dependent on =
circumstance I.E. it was a cold dry time of year & the pre ribbed boards =
were already at low emcs.=20
    Few of us run soundboard conditioning rooms at anything like the =
temperatures used by these early pianomakers. We certainly don't. You =
put a batch of already reasonably dry and properly stickered soundboard =
panels in a room running well upwards 120=BA+ and they are going to =
shrink quite nicely overnight. All you 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 is what I've always heard.(I forget where) Perhaps no one really =
knows but even if they were pressed in a dished caul with ribs that long =
& usually not very tall how much crown could the panel really retain =
over time. I recently saw  1920 ish Knabe upright with very tall ribs & =
enough of them. I didn't check the crown at that time but I will when =
next I see it. This piano was very well preserved ,great sound. Thanks =
for the replies.
     Dale
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