[CAUT] center pinning changes

[Ted Sambell]

Centers seizing up is by no means confined to Renner. I had two Chinese pianos do this recently. It would happen from time to time when I was in the factory. Everything would be fine until the pianos went to the pounder prior to final regulation, when a substantial number of centers would tighten sufficiently for the hammers to be standing up to the strings. If left unplayed they would free up again. The Chinese pianos behaved the same way; unplayed the centers were fine, but upon playing they tightened. I saw the same thing last year on Steinway replacement Tokiwa grand hammershanks. This can be very deceptive and easily misdiagnosed. It is readily fixed with a shrinking solution of two parts of methyl hydrate (denatured alcohol) to one of water. In my opinion, for what it's worth, the problem is in the manufacturing practices. We do not know what a particular maker is doing, but one continually runs into pianos one hundred years old in which the centers are still perfect. They used no lubricants, but evidently took the time to do things properly. Renner do wonderful work, so it is mystifying why they should have this problem. I just use a little teflon powder on my fingers when handling centerpins. In the old days we were taught to run the pins through our hair before inserting them. Of course, back then people washed their hair once a week. so it was a good source of lanolin. I think graphite is unnecessary, and  messy stuff anyway.

Ted Sambell
  ----- Original Message ----- 
  From: reggaepass at aol.com 
  To: caut at ptg.org 
  Sent: Saturday, September 08, 2007 8:59 AM
  Subject: Re: [CAUT] center pinning changes


  Hi Ric,

  So you think the graphite is the culprit?  Is the graphite only on the surface of the cloth, such that once you treat as per your post, they stay stable?

  thanks,

  Alan E.





  -----Original Message-----
  From: Richard Brekne <ricb at pianostemmer.no>
  To: caut at ptg.org
  Sent: Sat, 8 Sep 2007 1:55 am
  Subject: [CAUT] center pinning changes


  Hi Alan, others

  Renner has for years insisted upon using graphite in their center pin bushings. They state they have carried out extensive studies that refute claims that graphite can cause centers to seize after some use.  Lubrications usually have a temporary affect in my experience, but not always.  My general solution is to re-pin, reaming the bushing very lightly to get some of the graphite out, and working some telfon powder into the bushings before inserting the new pin.  Seems to allow for a tighter pining for same friction levels.

  Cheers
  RicB


    List(s),

    I've noticed something that I don't understand on a few actions with 
    Renner parts.  Initially, the pinning is just right (either came that 
    way or were made that way).  Eventually, some of the pinning becomes 
    too tight.  When I apply the smallest drop of lubricant, the pinning 
    that was too tight immediately becomes too loose.  This has happened 
    with both hammer and repetition lever centers.  I don't get it.  Has 
    anyone out there had a similar experience?  Does anyone have any idea 
    what is going on?

    Thanks,

    Alan Eder

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