[pianotech] Stringmaking Question

John Delacour JD at Pianomaker.co.uk
Mon Nov 24 00:12:24 PST 2008


At 23:02 -0600 23/11/08, Ron Nossaman wrote:

>Without measurements, how do you calculate the elongation to 
>determine where the wrap ends under tension, in relation to the 
>bridge pin, and especially the agraffe?

Are you serious?! The rubbing contains the lengths, the pattern 
strings (first and last of each section) test the accuracy of the 
rubbing, and the computer programme knows how much a given string 
will stretch under tension.  As to the lengths for the calcs, for 
curved bridges it's only necessary to measure every fifth speaking 
length (two minutes' work on the bench), for straight bridges only 
two measurements are needed; the computer interpolates the rest, and 
that's supposing that after 24 years of keeping computerised string 
scales I am sent a piano that I haven't done before.

JD




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