You can estimate the elongation, as I used to do, or you can calculate it, which I might or might not do, depending on my relationship with the stringmaker and my knowledge of his practices. What you and I cannot know or calculate is the tension which is applied to the core wire and the wrap wire on the machine as it is being wrapped. If the stringmaker gives due attention to these details, he is in a better position to make the necessary calculations. Another consideration is that the core tends to twist under the tension of the wrap wire pulling against it as it is being wrapped, more so near its mid-point than at the ends of the wrapping. If no compensation is made for this, the string may come of the machine with a slight corkscrew-like curl. This may or may not relax out of it by the time you see it. I know that Arledge has a controlled differential between the RPM of the two spindles that turn either end of the core wire to compensate for this, resulting in the string coming off the machine as straight as the core wire was before wrapping. I trust Arledge to do these calculations for me, and have not been disappointed. Depending on other stringmakers' practices and knowledge of them, I might do the calculations myself. Frank Emerson -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://ptg.org/pipermail/pianotech.php/attachments/20100121/08d60f8c/attachment.htm>
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