No downbearing ?

[Erwinspiano@aol.com]

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In a message dated 1/2/2004 8:41:36 AM Pacific Standard Time,=20
pianobuilders@olynet.com writes:
----- 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=20
uprights you want, but you'll only find a few with soundboards that were des=
igned to=20
have a crown and hence downbearing & Many of them sound very nice. In my min=
d=20
the upright soundboard is more of a mass driven system. I.e. long strings an=
d=20
big soundboards. These boards are tapered, thicker at the top in the treble=20=
&=20
gradually thin down to about 1/4" near the bass/ bottom end for flexibility.=
  =20
=20

Dale,

I suppose you have to define what is meant by "designed to have crown...."=20
>>Its true I could have said it doesn't appear that much crowning was a=20
designed feature. I do beleive they were expecting compression but it doesn'=
t seem=20
to coincide with the amounts of compresion and set we find in grand boards o=
f=20
the same era.Ie Mason Boards. It's fairly obvious to me that these boys were=
=20
aiming at very low emcs. I find more compression cracks in this piano than m=
ost=20
steinways.
At least until the transition from hot animal hide glue to "modern" syntheti=
c=20
adhesives (for this industry this took place between roughly the mid-20s to=20
the mid-30s) all pianos, grand or vertical, had at least some amount of=20
compression-crowning. This is regardless of what curve may or may not have b=
een=20
machined into the ribs. Of manufacturing necessity the soundboard panels wer=
e=20
heated to approximately 120=BA F for several hours before ribbing. It was lo=
ng enough=20
to thoroughly heat the panels and dry them to some very low moisture content=
=20
-- and, hence, shrink them -- prior to ribbing. By definition this is=20
compression-crowning.
  >> I have no doubts that there was some sort drying prior to ribbing but=20
with the uprights a mere few hours of heating isn't really going to take a=20
soundboard panel to an adequately low emc level for compression crowning. No=
ne of=20
us 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

Beyond this, Wolfenden (at least) was using a combination of rib- and=20
compression-crowning as a standard practice when he wrote the first edition=20=
of his=20
book (1914 wasn't it?). He made no mention of his practice being in any way=20
exclusive. Indeed, the impression one gets is that it was rather common amon=
g the=20
pianomakers of his day.
>>.. I wonder what piano he was building. If rib crowning was common  I must=
=20
say I've seen precious little it on many.(Knabe) I should think it should be=
=20
easy to spot. With  Upright being so long the taper of rib cut with crown=20
should be apparent. Do you know what i mean?
I think you have to look at other design factors that are different between=20
the overall vertical and grand piano design practice to explain what you are=
=20
finding. (Incidentally, my experience does not parallel yours. Of those I've=
=20
evaluated, verticals seem to have about the same residual crown, or lack the=
reof,=20
as grands of the same vintage and life experience. Most have little or none=20
with the occasional happy exception.)=20
....>>>>Though I believe that these pianos would benefit tonally  from crown=
=20
& bearing nevertheless many of these pianos (at least in my climate) do work=
=20
quite well with new strings& hammers, etc., & some bearing, provided that th=
e=20
board isn't seriously or irreparably deteriorated.

A couple of things you might want to consider are the generally lower qualit=
y=20
of wood used in vertical soundboards Vs that used in grands and the overall=20
length of the ribs.
>>>>This is a possibility
Another factor might be the variability of the microclimate surrounding the=20
instruments. How many verticals over the past century have spent a winter an=
d=20
summer or two backed up against an uninsulated outside wall?

Del

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