[CAUT] pre-stretching new string?

[Ron Nossaman]

> A semitone might be a bit much, but 30 cents or so is ok.  Chip tune the
> piano to 30 cents sharp, let sit for a couple of days, lift, level and
> tighten the bends at the bridge pins and the piano will settle pretty much
> right on pitch.  
> 
> David Love

I agree with David, and suggest you throw the string stretcher 
away, or better yet, melt it down into something useful and 
non destructive.


As to string stretch:

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 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, but the Teflon in the action will kill you at 
that temperature anyway, so there's no point in worrying about 
that.

Ron N