Pianotech

  • 1.  Bent center pins

    Posted 11-09-2020 08:56
      |   view attached
    I've been practicing for the RPT exam on an old, retired Hardman-Peck grand piano section that I harvested and noticed something odd.  It seems that every single jack center pin has a slight bend in it (see attached photo).  At first I was thinking that it might have something to do with trying to center the jack in the repetition window, but this doesn't make sense and I don't think it would accomplish that anyway.  My current theory is that they may have pressed the ends of the pin in a machine in order to avoid having the adjacent wippens from catching on the rough cut end of the center pin.
    Any thoughts?




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    Neil Vanderschaaf
    Round Rock TX
    512-577-1840
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  • 2.  RE: Bent center pins

    Registered Piano Technician
    Posted 11-09-2020 10:07
    Hi Neil:
    Believe it or not, it is standard practice to bend the pins to do exactly that, center the jacks in the window. If you repin them, you'll find that they rub. If there's an alternative, I don't know about it. It does sometimes cause a problem with friction or binding. You may also find some jacks that are indeed rubbing, and there are some tools to correct it by tapping the jack with a sledge hammer while supporting the wippen on one side, which bends the pin. Ok, so maybe a sledge hammer is a bit of overkill. But that's how to correct the misalignment.
    Paul McCloud
    San Diego




  • 3.  RE: Bent center pins

    Posted 11-09-2020 10:22
    Thanks for your reply Paul.  Unfortunately now I'm really confused.  First of all, I can't quite see how the bend would center the jack unless it is slightly off-center.  Secondly, it bothers me a bit because now the ends of the pin will be in the bushing at a slight angle which just seems wrong.

    Finally, what do I do if I encounter a pin like that on the RPT exam model?  How do I orient the pin that I have to replace so that the jack will end up in the center?  I've been noticing that many of the jacks that I've done have been extremely close to the edge of the rep. window.

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    Neil Vanderschaaf
    Round Rock TX
    512-577-1840
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  • 4.  RE: Bent center pins

    Registered Piano Technician
    Posted 11-09-2020 10:33
    Hi Neil:

    If it's slightly off center, and is working freely, there's no need for alarm. There will be a slight slant on the tip of the jack, but the knuckle leather will absorb it. I agree, it sounds wrong, but it does work. Otherwise, you'd have to redrill the hole in the jack or the wippen or both, rebush the hole or get a new one. I've had a few that were binding, and so I had to repin. But I had to center the jack again by bending the pin. Touche!

    How are you going to orient a pin? You mean if the pin is straight or bent? I would not use a bent pin to replace it.

    The exam is going to use a good wippen, not likely to have a jack that isn't pretty well centered. Or at least not touching. If you somehow find that to be the case, you'll need to point it out to the examiners.

    Paul



    Neil Vanderschaaf
    Thanks for your reply Paul. Unfortunately now I'm really confused. First of all, I can't quite see how the bend would center the jack unless it is slightly off-center. Secondly, it bothers me a bit because now the ends of the pin will be in the bushing at a slight angle which just seems wrong.

    Finally, what do I do if I encounter a pin like that on the RPT exam model? How do I orient the pin that I have to replace so that the jack will end up in the center? I've been noticing that many of the jacks that I've done have been extremely close to the edge of the rep. window.

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    Neil Vanderschaaf
    Round Rock TX
    512-577-1840





  • 5.  RE: Bent center pins

    Registered Piano Technician
    Posted 11-09-2020 12:31
    Hi Paul,

    An alternative method for centering jacks in the repetition lever window without bending the jack center pin is to heat the rep. lever post (wippen design permitting) until compliant, and then tilt it. This ia an old method, one that I learned from Bruce Clark (since it is the ONLY way to center jacks in WNG parts, what with their stainless steel center pins).

    Alan

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    Alan Eder, RPT
    Herb Alpert School of Music
    California Institute of the Arts
    Valencia, CA
    661.904.6483
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  • 6.  RE: Bent center pins

    Member
    Posted 11-10-2020 01:54

    Hi Paul and all,

    Another alternative for centering jacks is to bend the repetition lever pin in a similar fashion as the way you would bend the jack pin.  You would support one side or the other of the repetition lever support post fork(?) and strike the ecsaine/leather covered tip of the repetition lever with a small hammer.  This moves the "window" the jack is centered in rather than moving the jack.  


    I don't like centering the jacks by bending their pins as they sometimes get tight as a result.  I have no problem with repetition lever center pins getting tight as long as the spring can overcome it.

    Alan's method is a good one if you have time for it, as it doesn't require any bending of pins.

    Best,

    Luke



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    Luke Taylor
    Temple City CA
    310-386-7014
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  • 7.  RE: Bent center pins

    Posted 11-10-2020 08:32
    To center the jack, place the back of rep lever support on a hard square edge; on the side that is rubbing. Tap the end of the lever with a small hammer or such. This will bend the pin slightly to reposition the window. It is better to reposition the window than the jack. Bending the jack center pin will cause unwanted friction.

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    Regards,

    Jon Page
    mailto:jonpage@comcast.net
    http://www.pianocapecod.com
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