> While I don't know if Mike Spaulding is 100% correct that "it's all in > the bends", ------- Yes, he's correct. There's no such thing as pre-stretching because wire pretty much ceases to stretch as soon as it's at pitch (tension). This is from Mechanics of Materials, by Larson & Cox, published by John Wiley and Sons, 1947 "When an elastic material, such as steel, is loaded at ordinary temperature, it deforms in proportion to load almost simultaneously with the loading. Thereafter, the load may apparently act on the material for an indefinitely long long period without causing any further appreciable change in dimensions. Even if the material is stressed above it's elastic limit, after an immediate deformation there appears to be no further change in dimensions until there is some change in load." From Tool Engineers Handbook, by the American Society of Tool Engineers Handbook Committee, published by McGraw-Hill in 1949 "At room temperatures, creep is of no practical significance in steels, but does reach measurable proportions in such metals as lead, tin, and zinc." Innumerable sources agree that creep in steel is significant above 700°F. In other words, it's the bends. Ron N
This PTG archive page provided courtesy of Moy Piano Service, LLC