---------------------- multipart/alternative attachment 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 ---------------------- multipart/alternative attachment An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/pianotech.php/attachments/c8/02/09/3a/attachment.htm ---------------------- multipart/alternative attachment--
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