setting up for installing soundboards

[Ron Nossaman]

>
> My questions to those of you with experience are as follows;
> 1. what are your thoughts pro/con on atmospherically crowned boards


Firmly con. This type of construction has a built in short life span, and is an
extremely difficult process to control predictably.


>
> 2. Is the other method, radiusing the ribs and pressing the ribs/board into a
> caul of some sort?


Yes, this is my preferred method.


>
> 3.(this one is my question)What do they mean when they say 60ft radius as it
> applies to soundboard crown?


Just that. Theoretically, the soundboard crown will describe an arc segment of
a circle with a 60' (or whatever) radius. It doesn't really work that way in
practice, but that's the theoretical intent.


>
> He seemed to think that Steinway uses the atmosphere type method. 


That is correct.


>
> I told him when I was there I didn't remember which method they used but they
> had a very expensive machine for precisely cutting around the perimeter of
> the board so that it would tightly fit the inside of the rim. Maybe that
> tight fit, plus gluing onto a angled shelf, plus diaphragmatic taper all
> contribute to their boards holding their crown.


The fit of the soundboard to the case sides doesn't really have anything to do
with retention of crown, which Steinways aren't particularly known for anyway.
If anything, diaphragming the panel lowers it's expansion pressure and lowers
the potential height, and longevity of the resulting crown.


>
> Thank you for answering, I will save the messages for him.
> Doug Hershberger,RPT
> Aliso Viejo, CA 


Suggest that he do some reading through the archives too. There's a couple of
days worth of details and definitions of concepts there.


Ron N