The WHOLE free end ( top and bottom ), or just the top
edge of the free end ? What did the span of the bottom
of the rib, touching the base of your test stand do ?
Expand outward, contract inward, or serve as a
rotational axis and not move laterally in either
direction ? I sincerely would like to know.
Thanks!
Gordon
--- Donald Mannino <donmannino@comcast.net> wrote:
---------------------------------
Ron,
Very interesting demonstration - thanks for posting
it!
Can you tell us the approximate sample rib /
soundboard crown radius? Orif you could provide the
unloaded measurement of the difference from thebottom
of the soundboard strip (at center) and the cord line
to give anidea of how much crown was in the sample.
What style rib was it - crowned on top? Was there
any"compression" style crowning in the combination?
Don Mannino
At 07:04 AM 10/29/2004, you wrote:
Yesterday I proved this to mysatisfaction. I built and
load tested a model of rib 6 (numbered from theback)
for a Steinway D, attached to a 142 wide strip of 8mm
thick Sitkaspruce panel. This rib is 990 mm long
overall (65 mm shorter thanstandard on account of the
sound board cut-off), with an inner rimcontact of 40
mm on the treble-bent side, and 30 mm on the new
soundboard cut-off. At 0.75 degrees of downbearing
angle (a typical figureover this rib on a D), there
will be 10.6 Kg down bearing from the treblebridge and
6.4 Kg from the bass. When we applied this load to the
soundboard test strip, with one end of the strip
clamped to the bench and theother end free, it caused
the free end to pull in 0.05 mm (2thou).
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