No downbearing ?

[Delwin D Fandrich]

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  ----- Original Message -----=20
  From: Erwinspiano@aol.com=20
  To: pianotech@ptg.org=20
  Sent: December 31, 2003 5:56 PM
  Subject: Re: No downbearing ?


        Jean
    I agree with the rest of these posts.  Look at all the old American =
uprights you want, but you'll only find a few with soundboards that were =
designed to have a crown and hence downbearing & Many of them sound very =
nice. In my mind the upright soundboard is more of a mass driven system. =
I.e. long strings and big soundboards. These boards are tapered, thicker =
at the top in the treble & gradually thin down to about 1/4" near the =
bass/ bottom end for flexibility.   =20

Dale,

I suppose you have to define what is meant by "designed to have =
crown...." At least until the transition from hot animal hide glue to =
"modern" synthetic adhesives (for this industry this took place between =
roughly the mid-20s to the mid-30s) all pianos, grand or vertical, had =
at least some amount of compression-crowning. This is regardless of what =
curve may or may not have been machined into the ribs. Of manufacturing =
necessity the soundboard panels were heated to approximately 120=BA F =
for several hours before ribbing. It was long enough to thoroughly heat =
the panels and dry them to some very low moisture content -- and, hence, =
shrink them -- prior to ribbing. By definition this is =
compression-crowning.

Beyond this, Wolfenden (at least) was using a combination of rib- and =
compression-crowning as a standard practice when he wrote the first =
edition of his book (1914 wasn't it?). He made no mention of his =
practice being in any way exclusive. Indeed, the impression one gets is =
that it was rather common among the pianomakers of his day.

I think you have to look at other design factors that are different =
between the overall vertical and grand piano design practice to explain =
what you are finding. (Incidentally, my experience does not parallel =
yours. Of those I've evaluated, verticals seem to have about the same =
residual crown, or lack thereof, as grands of the same vintage and life =
experience. Most have little or none with the occasional happy =
exception.)=20

A couple of things you might want to consider are the generally lower =
quality of wood used in vertical soundboards vs that used in grands and =
the overall length of the ribs. Another factor might be the variability =
of the microclimate surrounding the instruments. How many verticals over =
the past century have spent a winter and summer or two backed up against =
an uninsulated outside wall?

Del
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