Breaking Strength of Strings

[Ron Nossaman]

>Ron,
>This thread brings up some interesting questions. Your formula kicked out a
>different set of numbers, than mine. Hmmm? This points out that there exists
>different formulae to accomplish approximately the same results, but not
>necessarily the same results. So, which is better/preferred/used by most,
>etc., is the first question.

As always, "better", "preferred", and "used by most" are three widely 
disparate concerns, each carrying considerable personal decision baggage of 
it's own. The first question is at least a month's worth.


>Second question is: why are there different
>formulae?

Mine's different because I adapted it from an existing formula to more 
closely reflect the actual reported breaking strength figures I had access 
to. Typically, the bass core wire has a lower tension limit than the 
treble, and I wanted the math to reflect that.


>Third: which ones are more current/accurate, (in relation to
>modern piano wire manufacturing limits/accuracy)?

Mine matches the figures I had when I put the formula together better than 
the others I've seen. If the figures are realistic, the formula's accurate. 
If not, then it's back to pot luck. I was most concerned with wire sizes at 
the top end of the wrapped monochords and bichords, since blending 
transitions often gets these break% up around 55%, and I wanted to know as 
closely as possible where I actually was there. Same for the top end, where 
I like that C-8 in the 53 or 54mm range and wanted to know how close that 
actually was to the yield point. The rest of the scale is typically not 
nearly that close to the limits, so break% isn't critical there except as 
another continuity indicator.


>I have always said that "close is only relevant to horseshoes, hand grenades
>and H-bombs". So, how close is close and should it or could it make a
>difference in fine tuning a scale?

Interesting. I've always thought that anyone claiming perfection either 
isn't paying attention, or hopes their audience isn't. For scaling, I'd say 
that just about any of them are fine, though I'll argue that at least one 
bass string maker is using a break% formula that is overly cautious. All 
these formulae do for you in scaling is give you an indicator of relativity 
from unison to unison, and tell you how close to the edge of mechanical 
limits you are. Scaling formulae are already  more accurate than they need 
to be for adequate scaling, for the most part, since most of the problems 
inherent in scaling relate to balance and transition. While I would like to 
see an impedance formula that more closely ties in with reality, the ones 
in use are still quite helpful as a relative indicator. At least in my opinion.


>For me, I think that the small nuances do make a difference in trying to
>make a mediocre scale better.

Yes they do, but beyond a certain resolution the numbers don't mean much 
except as to how they interrelate with the rest of the scale. It's like 
ETDs. They're already more accurate then the pianos being tuned with them, 
with the difference in tuning results being how they're used.


>Of course, we both know that, what really looks good, on paper, many times
>just isn't the real world, in piano scaling.

Oh yes, just as we know that what is often taken for granted as fine 
scaling as the hammers are butchered to try to make it work, is not.

But that's a rant for another day.

Ron N