Rib Thinning

Richard Brekne Richard.Brekne@grieg.uib.no
Tue, 27 Jan 2004 17:04:01 +0100


Farrell wrote:

> Hi Ric, sounds like you are moving along nicely on your project. My 
> understanding is that there are two trains of thought on this issue.
>  
> The first is a perhaps traditional view that suggests the panel must 
> fit snugly to the edge - I think this is part of the "circle of sound" 
> thing and reflecting soundwaves or vibrations or whatever. Like maybe 
> the sound might leak out the edge of the panel? Andre Bolduc pours 
> fiberglass resin into any gaps between soundboard panel edge and the 
> inside surface of the outer rim.
>  
> I think some more progressive thinking (IMHO) suggests that all you 
> need to do is have the edge of the soundboard firmly attached (glued) 
> to the inner rim. If the edge of the soundboard is immobilized (glued 
> to the inner rim), you have done all that matters.
>  

Thanks Terry,  I just wanted to make sure I wasnt doing something stupid 
either way. I take this too mean the idea is to insure enough gluing 
surface, and leave it at that. Certainly (at least)  in this case.

> If the board is now a little smaller than when you took it out, your 
> locator marks aren't going to be super useful in trying to figure out 
> where to position the soundboard. Likely the best method will be to 
> get the bridges optimally located. If you measured the original 
> speaking lengths, try a combination of reproducing the original 
> speaking lengths and good alignment of the speaking and backscale 
> portions of the strings (assuming they were aligned to begin with - 
> perhaps a big assumption!).

I took three spots on the bridge and measured back to the case inner 
wall. Sideways I actually dont have any measurements... probably dumb 
:)... but I suppose the panel shrunk rather uniformly so I will just 
position in the middle sideways. I havent tried refitting the bridge 
yet. It had 6 dowel holes that also went through the soundboard. I 
suppose I am going to have fun getting those right. :)... live and learn.

I'm planning to refit the origional bridge (after some steam twisting 
and bending to get it flat again) before gluing in the panel, as I am 
doubtfully I can get enough pressure on it for gluing otherwise.

> If you have good photographs of the original alignment, you can refer 
> to those. Presumably, the bridges have not changed dimensions much.

I dont think I do have pictures of the original alignment... per se... 
but I will look through what I took. New pics I can get !!
 

> Keep us informed. Photographs?
>  
> Terry Farrell
>  

This is great fun btw.  Changes ones perspectives quite a bit. If this 
works out well.. I may even try my hand at a real panel. Tho somebody is 
going to have to teach me how to notch a bridge really nicely first... hehe.

Cheers
RicB



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