soundboardinstal again

[Ron Nossaman]

>A very small case in point:  from what I've seen of a recent
>sales brochure from Bl"uthner, the company appears to be saying
>that they use rib crowning, and make their soundboard assemblies
>starting from 5% to 6% moisture content.  They refer to their
>approach to crowning as not aiming so much at spherical crown as at crown 
>along the line of the long bridge (which might be another way of saying 
>that they use rib crowning).

For what it's worth, soundboards aren't spherically crowned and never were. 
They take on a compound curve, but it is nowhere near spherical. As far as 
crown along the long bridge is concerned, It doesn't matter what crowning 
method is used. If there is crown along the ribs, there will be crown along 
the bridge.


>They also point out that
>they bevel the rims to fit the assembly's perimeter bearing surface.  In 
>this case, since (if I recall correctly) Ron has
>questioned the value of rim beveling, at least under certain conditions,

Del is the guy who first mentioned that, and I agree. And not just under 
certain conditions. This is the case in nearly all soundboards being made 
in the last 100+years. The rim bevel just doesn't make a significant 
difference.


>I wonder whether the maker is simply following its
>own (or even others') traditions, or has done its own research
>to try to determine whether or not it makes a difference. (There
>is, however, plenty about the experience of playing this maker's
>new instruments that engenders a great deal of "faith" or "trust".)

I think it is accepted as truth because it looks like it ought to be true 
and always has. One of my least favorite observations presented as 
justification for doing things like this is that it is "intuitively 
obvious" that it MUST be a necessary and beneficial thing. Intuitive and 
obvious to whom? "Intuition" is defined as "The act or faculty of knowing 
or sensing without the use of rational processes". Somehow, to me, this 
lacks substance and I want to know something of the science behind the 
assumption to make up my own mind and, if the evidence suggests, try it the 
other way and see for myself. When it's done contrary to "conventional 
wisdom", yet in accordance with the established and well documented 
physical properties of the materials used, and at no real world performance 
penalty observable by anyone looking past the dubious assumptions, 
conventional wisdom will still prevail most of the time in spite of the 
evidence to the contrary. So rims will continue to be beveled, soundboards 
will still be compression crowned, and rim spread will still be believed to 
be why soundboards go flat.

It will always be easier to believe than to verify.


>I've known from reading the list that length of backscale is
>considered important.  The response has made me think more about
>why there are rebuilders who (if I recall correctly) find it worthwhile to 
>to replace standard hitch pins with vertical hitch pins.
>
>Thanks,
>
>Randy Jacob

Both the long back scale and vertical hitches are less restrictive to 
soundboard movement.

Ron N