>* I don't have a clue. Would you, or anyone else, happen to have rough
>comparative figures on hardness and tensile strength of the two plate
>materials? Not that it would tell me a lot, but it would at least be
something.
>
>
>
Hi Ron,
I've got the figures packed away some where, I've been looking
for them, hell I must be getting old and a little slow of mind. But I
should find them this weekend.
But a few things from memory.
Free carbon in sand cast, lots of it, It actually acts like a lubricant at
the bearing points. Proof, note how black your hands get when dressing the
V bars of a grey cast plate. For those who are unfamiliar with free carbon
think graphite. This type of plate has a built in lubricant.
A personal theory is that the copious amount of free carbon within the
structure helps with acoustical damping and hence less aggressive forward
termination tone.
The flexibility of grey cast is quite surprising in the real world, a piano
that Del and I had some dealings with, was assembled with out adequate
bracing. ( I may add we are both innocent )
The Torsional stresses and hence plate movement could be noticed whilst
tuning the beast,
and would not stay in tune principally due to plate movement.
Will try to post data next week.
Regards Roger
Roger Jolly
Baldwin Yamaha Piano Centre
Saskatoon and Regina
Saskatchewan, Canada.
306-665-0213
Fax 652-0505
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