[CAUT] pre-stretching new string?

[Cramer, Mark]

Interesting Ed,

what I didn't hear you say though, is whether you do this to each and every coil in the course of a restringing job (or just to stabilize a single-string) ... and your advice is too valuable for me to assume... so do you?

And I trust your findings (wow, 150 cents!) but have to ask as well, do you feel this slack within the coil, if left unaddressed, actively contributes to instability over the life of the piano?

Or, would we find a 150cts of slack in the coil of a well-seasoned otherwise stable older piano?

When re-stringing, I lift the coils above the plane of the becket, pull to pitch, then tap the coils down to plane. Along with squeezing the beckets, this step may be repeated several times.

This action alone seems to drop string tension 25 - 30 cts, and it's obvious the slack is coming from nowhere other than the coil.

Beyond that, I've imagined (and that's mainly what I do :>) that it would be very difficult under normal tuning conditions to realize any more slack from the coil, due to the friction of the string over a very large surface area, including both the tuning pin and adjacent coils.

(still with me?)

So one last time, before I dial in the vice grips, do you feel any "remaining slack" in the coil, after I'd settled coils in the manner described above, would actually release into the active string length overtime?

thanks,
Mark Cramer,
Brandon University







   




 

 






Greetings, 
    The majority of the flattening of a new string is in the 
COIL!!!!!!!!!!!!!!!!
There is usually about 150 cents worth of slack in a three turn coil around 
the tuning pin.  If anybody doesn't believe this, simply put on a new string, 
tighten it up to a semitone sharp and then, with a small pair of vise-grips, 
make sure the becket is smashed in tight.  Then, grab the coil with the grips, 
(set them just short of locking so you get maximum compression on the coil), 
and begin twisting in the direction of the string.  You will hear the pitch 
plummet.  I routinely do this on string repairs and after a follow-up of 10 or so 
cents a week later, the strings stay put.   
    Theoretically, the becket will never see the tension of the speaking 
length because of the friction taken around the pin, but if you stroke the coil in 
this fashion, you will move a tremendous amount of slack into the top string.
   On bass strings, it is well known that squeezing the hitch pin loops will 
cause the string to drop, but if you will grab the barrel,(the tightly wound 
finale of the hitch pin loop), and give it a gentle back and forth twist, (not 
a rotational twist but, rather, side to side), you will hear anywhere from 10 
to 20 cents drop.   
   Ron is right, carbon steel reacts to stress almost instantly. The bends 
around the bridge pins will take a while for the plastic deformation that occurs 
on the outside circumference of the bend to allow the further deformation 
through the diameter of the wire, but that is still neglible compared to getting 
the slack out of the coil. 



Ed Foote RPT 
http://www.uk-piano.org/edfoote/index.html
www.uk-piano.org/edfoote/well_tempered_piano.html
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