Rib Thinning

[Overs Pianos]

Richard,

Terry's posts have been right on the money to date.

>>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.

Absolutely. I like to get a close fit between the rim and panel for 
aesthetics, but its structurally unnecessary.

>. . . 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.

If the dowels go through the ribs, get rid of them. I recall from 
reading an earlier post of yours on this topic that your board is 
primarily rib crowned. The most effective way to wreck the structural 
integrity of a crowned rib would be to stick a dowel through it. 
Quite a few of the CC brigade (Steinway included) have a habit of 
doweling through each rib - not a good idea, but at least it won't 
kill a CC board stone dead.

The D I'm rebuilding at present had dowels through each rib. But the 
board I'm building for it will be 100% rib crowned with no panel 
compression (just in case you're wondering, yes the panel will be 
laminated). The dowels will be absent. If you do feel compelled to 
use dowels place them between the ribs where the sound board buttons 
are typically placed. At least they won't do any harm there.

>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.

Just make up a few dummy bridge sections and do some practice before 
you commit to the real thing. After a bit of practice you will learn 
what not to do. All the best.

Ron O.
-- 
OVERS PIANOS - SYDNEY
    Grand Piano Manufacturers
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