Pin flexing/bending/twisting

[Alan R. Barnard]

Tuning pin friction generates a LOT of heat, as y'all have probably experienced, when they are turned round and round to remove them. It SEEMS like even more heat is generated when they are spun quickly, but I suspect it is only because there is no time, in that case, for any of the heat to dissipate. So some heat must always be generated, even in tuning and heat does things to wood and glue. Does it contribute to wear or make the hole "slicker" (less grabby) over time? I dunno.

Alan Barnard
Salem, MO
Joshua 24:15



----- Original message ----------------------------------------
From: A440A at aol.com
To: pianotech at ptg.org
Received: 11/05/2006 8:01:35 AM
Subject: Re: Pin flexing/bending/twisting



><<  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
>