>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
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