Moving Action Lines of Center

[Isaac OLEG]

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Hello gentlemen,

Just this fast thought :

is not there a third "magic line" between the pivot of the repetition lever
and the hammer center pin , where the roller/jack is more or less located at
letoff, may be because the jack would reengage better then (lesser  friction
path ) ?
indeed not a leverage question anyway.

Regards to all.

Isaac OLEG

Entretien et reparation de pianos .

PianoTech
17 rue de Choisy
94400 VITRY sur SEINE
FRANCE
tel : 033 01 47 18 06 98
fax : 033 01 47 18 06 90
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  -----Message d'origine-----
  De : pianotech-bounces@ptg.org [mailto:pianotech-bounces@ptg.org]De la
part de Erwinspiano@aol.com
  Envoye : samedi 18 janvier 2003 21:45
  A : pianotech@ptg.org
  Objet : Re: Moving Action Lines of Center


  In a message dated 1/18/2003 7:09:18 AM Pacific Standard Time,
mfarrel2@tampabay.rr.com writes:


    Subj: Moving Action Lines of Center
    Date: 1/18/2003 7:09:18 AM Pacific Standard Time
    From: mfarrel2@tampabay.rr.com
    Reply-to: pianotech@ptg.org
    To: pianotech@ptg.org
    Sent from the Internet


        Terry


          In my limited experience of checking the "Magic line" at the
knuckle I've noticed that even on the best of actions the only time the
knuckle gets close to the line is at the very end of the key /action stoke.
(I think Ron Overs action is the exception.) So maybe the parameter is ,
that the closer the knucle is to the line the better. I  think the most
advantage gained is at the wippen heel/capstan contact point. When this
convergence line is right the action gets very  fluid. Or , as My colleague
Bob Davis so succinctly put it to me the other night is , that leverage is
leverage.
     Meaning that primarily you can move two things to increase action
efficiency , reduce lead and increase hammer weight.  These two are the key
balance point relative to the capstan or the knuckle placement relative to
the centerpin.  Other than that the lines of convergence are where friction
can seriously be tamed , there by reducing the  need to add lead to overcome
it. Of course for me all this moving balance points and convergence lines
around still has to land me within  .390 ish dip and a 1 3/4" to 1 7/8" blow
distance with a 1.5mm let-off.
     Somebody else jump in here and tell me something I might be missing.
        Dale Erwin



    I'm having a difficult time imagining how to change the position of the
knuckle/rep lever contact relative to the magic line.

    I can see quite easily how to manipulate the wippen heel/capstan
contact - taller or shorter heel, capstan up and down, and/or move capstan
forward or back. Lots of easy opportunity to put that contact anywhere you
want it.

    I have a 1947 Baldwin action where the magic line passes through the
knuckle just above its center with the key at rest. At full key depression
the rep lever is almost up to the magic line.

    A tiny knuckle would do it, but I have never seen one so small. I
suppose you could move the wippen flange down (move rail?) somehow. But
that's pretty weird.

    Is there some easy thing I am overlooking?

    Terry Farrell




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