uprights, hammer boring

[Dave Nereson]

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  ----- Original Message -----=20
  From: Greg Newell=20
  To: Pianotech=20
  Sent: Wednesday, March 12, 2003 10:14 PM
  Subject: Re: uprights, hammer boring


  Keith,
          I believe that Newton Hunt wrote something about this a while =
back on this list. You could search for it in the archives. If you find =
it feel free to repost. I'm sure many would be interested. I seem to =
remember that bore distance was the same as a grand in that butt flange =
center pin to string is the bore distance. As far as rake goes I really =
don't remember. I don't replace a great deal of hammers myself.=20
          This brings up a question for me that perhaps someone can =
answer. Although I don't replace many sets of hammers on uprights I =
presently have occasion to replace a set on an old Gulbransen upright. I =
tried to measure from the butt center pin to the string and I just =
couldn't get a measuring device in there to take the measurement. Anyone =
have a tip on what I could use to get a good reading? Might be too late =
for this set but I'd sure like to know for the next one.

  Greg


  At 05:28 PM 3/12/2003, you wrote:


    I gave the technical on hammer boring at the chapter meeting, (with =
the back-up of the RPTs at the meeting), and nobody could explain what =
the criteria would be for determining hammer bore distance and rake for =
optimum performance on an upright. Sure, go by the original is an easy =
answer but what if it looks as if somebody who "hadn't a clue" put those =
hammers on. I have 3 old uprights here, a 1909 Smith and Barnes, a 1911 =
A.B. Cameron, and a 1906 Kohler and Chase. The first two, the hammers =
shanks are close to parallel with the string plane, and the rake is =
minimal. Or, worded differently, the bore distance is the distance from =
the hammer flange center pin to the string plane. Rake is 1 or 2 =
degrees.=20
    The Kohler has much more rake, 5+ degrees and the shank is at the =
similar angle to the string plane so the hammer is square to the string =
plane when it hits.
    Why?
    Should I be looking at the angle of the jack to the whippen at the =
start of lift? The hammer butt/jack angle at let off?
    Or maybe it was something simple, like the little bit more clearance =
that could be had by moving the action closer to the strings.
    Anybody?
    Keith Roberts

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  Greg Newell
  mailto:gnewell@ameritech.net=20



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  Can you remove just a couple damper levers and butts to get a small =
ruler in there?   --Dave Nereson, RPT, Denver

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