Pin flexing/bending/twisting

[A440A at aol.com]

<<  Has anyone done a study of the negative effects that occur to a tuning 
> pin or the pinblock while tuning? I service a new-ish 7' Bosendorfer for 
> a Boeing engineer, who is a hobbist with older uprights and we've been 
> discussing the rigors the pin endures>>

Greetings,
   I have many pianos that I have tuned at least weekly for the last 25 
years. Some of the stage and recording studio pianos I care for have been tuned 
twice or more weekly for all this time.    I cannot discern any negative effects 
that tuning has had on them.  The pins at C88 have aged the same as the pins 
at the bass break,(which seem to get a LOT more twisting in a given year than 
most of the rest of the piano).  
   In 1980, I restrung a 1966 Steinway D that a former tech had restrung 
(with the totally wrong sizes of wire), in 1974.  I replaced the 3/0 pins with 4/0 
pins.  At the time, I had never heard of, or had, tendonitis, carpal tunnel 
syndrome, or rotator cuff problems associated with tuning.  I didn't mind the 
180 in/lbs of torque that the 4/0 pins started with.  I figured they would 
loosen up with time and tuning. 
 WRONG!  This piano is still a bear to tune because I have never seen these 
pins change their torque.  
      The only times a pinblock has shown the effects of pin rotation in my 
experience is when some ignorant, mis-informed, insensitve, yahoo has replaced 
a string by turning the pin out three turns and then wound the new string's 
coil around it by turning it back down!  Every time I have seen this done, the 
affected pin has lost a significant amount of torque.  (Why don't we call that 
one a "dummy-pin" when they do that, rather than the spare one I use to form a 
coil on the replacement string?)
     I think the small increments used in tuning have no effect on pin 
torque, but the full rotation possibly swedges the hole by whatever amount of "out 
of roundness" that the pin has. 
Regards,



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