[pianotech] --Centering the bridge--was S&S something

[David Love]

Ron:

I've never quite understood why you (and others who do designs similar to
you) *don't* fully diaphragmize the panel.  I understand why one wouldn't
necessarily thin the panel in a compression crowned board as it reduces the
strength in the panel needed to form and maintain crown under compression.
But in your case you don't need that.  In addition, you taper the ribs as
they approach the perimeter--in fact by a good amount starting 1/3 into the
length of the rib, you've reduced the overall mobility of the board by
installing a large cut-off bar, increased the relative stiffness of the rib
scale, increased the grain angle to add additional stiffness.  So why
wouldn't you do a full diaphragmizing of the panel in this type of design in
order to create the greatest amount of mobility for the panel that remains?
You've already accounted for stiffness by the rib scale alone as if the
panel isn't there (or so you've stated in the past).  It doesn't make sense
to me.    

David Love
www.davidlovepianos.com


> If I'm using tight grain Sitka spruce I will want to thin the entire
> panel to 8 ish mm and the thin it at the rib scoops/perimeter and
> further into the panel.

I haven't used anything but a constant thickness panel for some time.


Ron N