[pianotech] Belly talk

[Ron Nossaman]

On 12/1/2012 9:52 AM, Jim Ialeggio wrote:
> Dale said:
>
> <The inner rim has an approx 1 1/2 degree bevel cut into the inner rim
> at the factory. Set a straight edge on it & it becomes apparent.
>
> This is precisely the point I'm trying to make.  You "prove" the bevel
> and its orientation by placing a simple 2 dimensional straight edge at
> some arbitrary point and see a bevel of some sort. Then infer this 2
> dimensionality to a 3 dimensional soundboard panel, which is not domed
> but crowned across the grain(roughly), and variable throughout, because
> the rib arc lengths vary. Where is this 1.5 deg bevel at the bass end of
> the board when we beat the panel tail into submission??

He said it was an approximation, which is true and correct.


> Further, the 1.5 deg bevel is not matching the "dome" in a cc board,
> since a 60' or even 40' radius board would be meeting the rim at less
> than 1 deg, depending on the length of the rib.  This means, either way,
> flat or rastened, even if rastened perfectly, localized stress is added
> to the panel edge at gluedown.

Yes it is. So why is that so universally presumed to be "bad"? It's like 
the crown is an arch thing - intuitive, belief without substantiation.

Ron N