On Dec 6, 2009, at 2:53 PM, Ron Nossaman wrote: > Using your figures, C-4 goes 83lb, 94lb, 118lb, 145lb, and the break > % remains 34% for both the Sanderson and Hays formulas. > > For the C-7, it goes 147lb, 167lb, 210lb, 258lb, and the break% > remains 61% for Sanderson, and 60% for Hays. > > My numbers correspond to yours for the Rhodes formula. The other one > isn't a formula at all, but a lookup table. I understand about the look up table: an embedded chart of break point figures something like we see in the Schaff catalogue. So it is going to have some numerical inconsistency compared to a break point generated from a mathematical formula. And I understand that the mathematical formula is based on a wider sampling of batch tests. That Hays and Sanderson are essentially the same in their predictions. So far so good, Then you say your number correspond to mine for Rhodes. But my Rhodes figures show a progression of break%. For C-4, 29.2, 29.8, 31, 32. For C-7, 52, 53, 55, 57. (The second series of figures I posted were from Rhodes, with tension converted to Kg for consistency. But the Lbs tension are precisely the same as yours). So why the inconsistency? I'm not arguing, just asking. If the math is the same, the results should be the same, no? Or maybe you meant something different by your numbers corresponding to mine for the Rhodes formula. Regards, Fred Sturm University of New Mexico fssturm at unm.edu
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