Crowning methods, was soundboards.

[J Patrick Draine]

On Jan 21, 2005, at 12:19 PM, Ron Nossaman wrote:

>
>> So some panel compression is still utilized but  crown not dependent 
>> on compression that much to form crown or maintain it & even in the 
>> driest invirons the crown won't shrink out of exisistence.
>
> Not me. My boards are rib crowned AND rib supported. I design rib 
> scales that would have crown under string bearing if the panel wasn't 
> there at all. Compression in the panel is minimal in my boards, and 
> mostly to prevent or minimize cracking in dry cycles. Since there is 
> little compression built in, there is little crush damage in wet 
> cycles, making cracking in dry cycles less likely. Time will tell, but 
> I don't see the dramatic wet season compression ridges in my boards 
> that I see in Steinway and Yamaha boards.

What RH do you glue the ribs to the soundboard at? I assume anything 
lower than ambient RH would induce some compression crowning (once the 
piano was exposed to something higher, say, summer's humidity -- today 
the RH is frightfully low) -- but I freely admit that's just a gut 
reaction, not a calculation.

Patrick