Nature of tuning pins

[David Nereson]

     Cut threads are actually cut, or scribed, into the metal.  Imagine chucking a smooth piece of rod into a drill press, then holding the teeth of a hacksaw against it as it rotates.  If you were to move the hacksaw up or down, it would cut a groove, or "thread," into the rod.  Rolled threads are simply impressed into the metal by pressure.  I imagine they're cold-rolled, i.e., the metal is not heated up again just to press the "threads" (grooves) into it.
    Neither type of "thread," of course, is as deep or accurately machined as the threads in a machine screw, wood screw, or sheet metal screw.  
    --David Nereson, RPT  
  From: Kendall Ross Bean 
  To: pianotech at ptg.org 
  Sent: Monday, July 07, 2008 9:45 AM
  Subject: Nature of tuning pins


  Hi, I haven't posted to the listserve before so let's see if this works.

  I had some questions about the different types of tuning pins and wondered if someone here could answer them. (I'm trying to write an article about tuning pins).

  It might be nice to have some discussion on something that many technicians seem to take for granted: why tuning pins come in the types and form that they currently do.

  (This may have all been covered before somewhere in the Archives, but if it was, I couldn't find it. So if it's there, I apologize in advance; could someone just point me to where it is? Thanks.)

  I've attached a photo for reference. 

  The photo refers to the three basic types of tuning pins we routinely see. (These were all photographed together at the same time on the same white background. The photo is "unretouched." -The colors in the photo seem to be fatihful to the genuine articles.)

  On the far left is a blued steel pin, in the middle a nickel plated pin, and on the far right a nickel plated/blued thread pin. (The end pins are Nippon Denro, the middle pin I think from an Asian piano, maybe Kawai, as it seems to be metric.)

  The pin in the middle has generally fallen into disrepute (I think I know why, because the threads are plated, right?) -but perhaps we need to re-examine this. Maybe this type of pin is still valid for certain extreme humidity applications?

  The following questions pertain mainly to the "blued" vs "nickel-blued pins".

  The questions I have are:

  1) Why are the threads on the "blued steel" pin a different color than on the "nickel-blued" pin? (also - Why aren't the the threads on the "blued" pin the same color as the unthreaded portion of the pin?)

  2) If the threads on the "nickel-blued" pin are cut after nickel plating, (which should remove the plating on the threads right?) and then are heated in the bluing oven, why aren't they the same color blue as the unthreaded part of the "blued" pin? 

  3) I am speculating that perhaps the threads on the blued pin are cut after bluing (which removes the bluing, to a certain extent, just like it removes the layer of nickel plating on the nickel blued pin) while the threads on the nickel blued pin are blued after cutting. Does the order in which the operations are done affect the quality of the thread? Does having to cut through nickel plating produce an inferior thread?

  4) Would anyone here care to restate why the blued pins (as opposed to nickel-blued) are preferred over the nickel-blued by many piano technicians?

  5) What is the real purpose of the threads on the tuning pin, (besides to help back the pin out in restringing. One source I have read says the threads make it easier to turn the pin in the pinblock (as opposed to an unthreaded pin). Any thoughts on this?

  6) Today apparently all tuning pins have "cut" threads, as opposed to "rolled" threads. Why is this? What does "rolled" threads mean? Why would they be inferior to cut threads?"

  7) Catherine Beilefeldt, in her book "The Wonders of the Piano", in describing the process at AMSCO (when it was still around), says that there both the nickel-blued and blued pins were blued after threading. Does anyone know if Nippon Denro does it differently? How about Fly Brand? Diamond?

  8) What, exactly, are the infamous "reverse cut" threads that were touted so highly by certain sales reps and dealers of Japanese pianos?

  9) What about Larry Fine's and Art Reblitz's contention that if this were really the case (if the "reverse cut" or "reverse thread" pin turned more easily in one direction than the other) it would wear the pin block out faster?

  10) Why, really, did manufacturers (except Bosendorfer) stop using tapered pins? 

  I have a number of books that touch on the manufacture of piano tuning pins, but none that really seems to have more than a superficial understanding of why tuning pins are made the way they are today. 

  If anyone knows of a reference work or resource that would have the history of the development of tuning pins, or an article in the PTJ (or even a thread in the CAUT or Pianotech archives) that addresses these issues, I would be very grateful if they would let me know where I can find it. You can either post your answers on the listserve, ideally, where all could benefit, or e-mail me personally at address below, if you prefer.

  Sincerely,

  Kendall Ross Bean
  PianoFinders 

  (e-mail: kenbean at pianofinders.com)



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