Balwin 6'3"

[Roger Jolly]

Hi Tom, 
            The nose bolt has two functions,  1. It prevents the plate from
bowing upwards by reducing the span.  2. The secondary effect is to improve
tuning stability by making the plate more rigid.  Depending where the bolts
are located, the length of span and amount of plate flex can be
significantly reduced.
If I were designing a plate and had to install bolts to prevent plate
ringing, I think I'd go back to the drawing board and strategically add
mass. Because each time you drill a hole in the board, to allow for a bolt,
you create an area for cracks to start.
The stripped nose bolt could have been stripped because the plate elevation
was incorrect from the start, then some one cheated by tightening the bolts
to obtain bearing. Humidity, stress, and the type of lumber used in the
support post, conspired to cause the threads to strip.
Plate nose bolts are meant to just come into contact with the bottom of the
plate and then be tightened. In the case of plate screws, (no support under
the plate) these should only be tightened with caution after the piano is
strung, to prevent stripping.

Regards Roger 





>Which raises some questions: Are nose bolts absolutely necessary to
>maintain the integrity of the plate or are they just there to dampen the
>ringing? Does it depend on the piano? How does a nose bolt get
>stripped?????
>
>Tom
>-- 
>Thomas A. Cole, RPT
>Santa Cruz, CA
>mailto:tcole@cruzio.com
> 
Roger Jolly
Saskatoon, Canada.
306-665-0213
Fax 652-0505