Rescaling question

[Roger Jolly]

Greetings Gordon,
                  With out doing a complete stress analysis, you are asking
for problems that you would find difficult to cover, worst case a broken
plate. You are looking at an extra ton of tension, if a great deal of this
extra tension is more localised to to a certain area then the plate may
really flex in that region , and cause significant tuning instability.
With that amount of increased tension, besides analysing the plate
structure, the plate mounting system should also be looked at, length of
spans re, nose bolts ect that will prevent vertical deflection.  Many of
these off beat small grands have little or non effective rim bracing, so
check very carefully. 2 to 400lbs would be the upper increase to be safe.
Regards Roger



At 04:22 PM 14/08/98 EDT, you wrote:
>List,
>
>I'm working on a 4'10" Lagonda Grand, (Jesse French) originally built in
1929.
>This instrument is to be used a high school.  It is a pretty tinny sounding
>instrument.
>
>I bought Tremaine Parson's PSCALE program, and put all the information in and
>came up with a pretty nice _looking_ scale.  (This is my first venture into
>rescaling)  My concern at the moment is that the program calculated the
>original scale tension at 38,643 lbs. and the scale I worked out was
>calculated at 40,332 lbs.  My two questions, (no doubt I'll think of more)
>are:
>
>1.) Is this acceptable?
>
>2.) How do you figure what a plate and frame can take?
>
>Many many thanks in advance for any help
>
>Gordon Large, RPT
>Mt. Vernon, ME
>
Roger Jolly
Baldwin Yamaha Piano Centre
Saskatoon and Regina
Saskatchewan, Canada.
306-665-0213
Fax 652-0505