center pinning question - answered?

[Joe And Penny Goss]

Hi Allen,
Ever use a bass hammer to remove paint scuffs from the front of the keybed on an old upright?
Yes felt can, over time, remove metal.
At least thats the way I view it. <G>
Joe Goss RPT
Mother Goose Tools
imatunr at srvinet.com
www.mothergoosetools.com
  ----- Original Message ----- 
  From: Allen Wright 
  To: Pianotech List 
  Sent: Friday, May 16, 2008 2:59 PM
  Subject: Re: center pinning question - answered?


  Rafael,


  I don't think my technique or approach to pinning is the problem. I'm using the right tools, I've been doing this work for a long time, and am careful in my approach. I'm well aware of the pitfalls you mention. The original Hamburg pins, although cut on both ends, were done very neatly, and I don't think they're tearing the cloth much, if at all, when they're removed - although I agree that can be a problem if one isn't careful.


  Today I looked very carefully at quite a few of the original pins and compared them with the new ones. On average the original pins had 12-15 swings, and registered 0 - 1 gram resistance. The new pins (exact same dimension, or if anything sometimes a hair smaller) create 3-4 grams resistance and 6-7 swings. (This is after working the flange a bit to compact them a bit with the new pin).


  I carefully mic'd just the ends of many of the old pins and found them to be a half-thousandth smaller (50.5 rather than 51). So my operating theory at this point (until someone convinces me I'm wrong) is that indeed (as my shop mate - and also Wim Blees in an earlier post - suggested) the pins themselves have worn slightly. At first this seems unlikely; but then again, after 70+ years of wear, perhaps it's not surprising that some wear would take place due to the friction from the bushing cloth turning hundreds of thousands of times? 


  I've saved some of the pins, and will try and find a microscope to look at them with. Perhaps someone else out there has already thought this through. I'd be interested to hear.


  Sincerely,


  Allen Wright, RPT
  London, UK


  On May 16, 2008, at 4:47 AM, Rafael M. Huberman Muñiz wrote:


    Allen,


    I think that the problem is with something in your repinning technique. Either is your device for pushing the old pin out (punch, pliers, etc.) or the way you push the new one in, or the things you do in between.
    The first one: you have to be very careful when you push the pin out. The first thing is to note if the old pin has rough edges (one or both of them) due to technicians that cut both sides of the pin after inserting it or, worse than this, technicians who file the end of the pins so you don't see the rough cut but a smooth surface. If there is only one side cut then you have to push the pin out by the clean side being careful to put your tool right in the middle and realy straight so you don't scratch the bushing. It's very important not to go all the way through with the tool because you will push the bushing inwards tightening it the same way that the tool for tightening key bushings works. This depends on the tool you use… If the pin has cuts on both sides or it has been filed then whatever you do will damage the bushing…  So, pushing the old pin out can make damage to the bushing that will result in tightening temporarly the bushing. Notice that I said temporarly. if you put the same size of pin after a few weeks it will be loose as it was the other one, or even worse if you loosed the bushing  with a reamer or file for fitting the new one… If you are repinning there is no way you will put same size pins, it have to be at least one size up.
    I won't talk right now about sizing up the new pin, but once you got it right then you have to be very careful tu put it straight and push it with a straight surface so you don't tight it when you press at the end (there are some tools that have an indentation for the pin and can work as the key bushing tightener tool).
    So my assessment is that there is no wore in the pins but some kind of swallow of the bushing while in the process of repinning.
    To test if something like this is happening just take one of your tight repinned piece and apply one drop on each side pf protek center pin lubricant and wait a few minutes and balance it a few times and you will notice that it is loose. If this happens you need to put in a thicker pin.


    Rafael
    _________________________


    Rafael M. Huberman Muñiz


    ArtePiano
    Jazmines #309, Col. Reforma
    Oaxaca, Oax. CP 68050
    México
    +52(951)5152629
    044(951)507-0960



















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