> >accelerated action design, right?Fw: Ideal leading pattern: more questions

[Erwinpiano]

David,

----- Original Message -----
From: "David Love" <davidlovepianos@hotmail.com>
To: <pianotech@ptg.org>
Sent: Thursday, March 29, 2001 7:38 PM
Subject: Re: Ideal leading pattern: more questions


> So this model S I am trying to solve has what appears to be another quirk.
> Admittedly, I don't make this measure of comparison very often but, the
> capstan to balance rail distance varies by about 6 mm from end to end,
i.e.,
> note #1, the distance is 106 mm, and note #88 is 112m

      If you measure a few stwys you will find this is all to common.

 The capstan centers
> underneath the heel at both ends.  It is counterintuitive if this is the
> design.  I operated under the assumption that the balance rail, capstan
> line, front of key line were all parallel.  If this is true (please
correct
> me if it isn't)  it would seem that brackets were not squared up with the
> frame and that the capstan line was then drawn at an angle.  Could this
> explain why I seem to need an excess of lead in the upper end of the
piano?

  Yes the action brackets are not squared up and it does account for the
increase in weight in the top end and the regulation will need to be
compromised somewhere. If blow distance stays the same dip will have to
graduate in depth for gradual changing action geometry/capstan line. If dip
stays the same (.390) the blow distance will have to vary to provide for
uniform after touch.
  The capstan line is the most variable part of the stwy action setup
because of the way the piano is made and as you can see some of them can
pose problems for us when doing this type of work.
  Another solution is making new keys and fixing the key ratio.  The capstan
line will then be paralell to the balance rail but not necesarily the front
of the key as the key length in larger model are longest in the bass and
shorten intl the treble.
         One last thing.  When measuring the key lengths to determine key
ratio remember that the piano key is a cantalevered lever.  measurements are
taken from the top front of the white key top to the bottom of the keypin
hole and from keypin hole to top of capstan.(Thanks Rick Wheeler) Use these
no.s to calculate the key ratio and in the case of your S sstwy you find a
variable key ratio from end to end.

Dale Erwin

> Interestingly enough, though the downweight diminishes 50-47 from 1-88
(and
> the upweight follows inversely), the action actually feels heavier in the
> upper end of the piano.  My sense tells me that with the capstan line
moving
> ever farther away from the balance rail as you progress from bass to
treble,
> that the action becomes more poorly leveraged and therefore feels heavier
in
> spite of the fact that it is getting lighter.  Feedback is appreciated.
>
> David Love
the way, it is
.
> > > >

>