A string's treatment/ Isaac

[Ron Nossaman]

>Isaac,
>You said: "BTW, Joe, we checked the scaling of a little grand Shimmel, with
>55 mm
>at c8 and 93% of breaking strain (at 442 pitch) this is  not really a
>low tension scale, other octaves give us values between 75 and 85%
>breaking strain. where do that appreciation comes from ? (other models
>may be ?)"
>First: What the heck is with the "442"? Second: I don't know what kind of
>scale program you are using, in relation to formulae, but the numbers you
>posted, IF they were correct, (which I believe they are NOT.), would be a
>disaster waiting, (a short time), to happen. The common rule that I was
>taught, (by Del), was not to exceed 55% - 60% of the breaking strength,
>EVER!,unless it is impossible to avoid!!

Joe,
At 442 (whatever the reason), with a 55mm length, I get 76% with (I think) 
Sanderson's formula. To keep c-8 under a calculated 60% at 440 would mean 
keeping the speaking length at or under 49mm. I'd rather not, thanks. In 
real pianos, c-8 lengths up to 54mm (72%) are practical under normal usage. 
For wrapped strings, I agree that they shouldn't go much over 55%.

Ron N