Touch weight

[Ed Sutton]

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Vince-

Wow!  Easy to calculate.  (I thought it was one of those progressions to =
the infinitesimal formulas.)

This gets exactly to the unanswered question when setting front weights, =
i.e. one in front or two in the back? etc.

In fact it should be fairly easy to make a reference chart in, say half =
inch increments.

I'm rebuilding an action after Xmas, and I just might knock out the old =
weights, plug the holes and go for broke.

Thanks very much!  This is a real Xmas present!

Ed Sutton
  ----- Original Message -----=20
  From: madelyn mrykalo=20
  To: College and University Technicians=20
  Sent: Friday, December 19, 2003 8:47 AM
  Subject: Re: Touch weight


  Ed-
  We measured the weight in grams of a lead for the mass (m).  I.e. 14.1 =
grams for a 1/2 inch lead is usual, then for r we measured the distance =
of the lead from the middle of the balance hole to the middle of the =
lead in inches.  So I=3D14.1X4"  would be for one lead (I just picked a =
figure 4" for the distance).  Then if there is another lead, do the same =
for it, adding it to the first lead.  So I=3D14.1X4" + 14.1X2" (if the =
second lead is 2" from balance) and so  on.  This gets some figure that =
sort of arbitrarily represents the moment of inertia, larger in the =
bass, and graduating to smaller as we go up into the treble.  I think =
with some research the moment of inertia figure can come to mean =
something to us.  Empirically finding out what kind of figures pianists =
like would help set a general standard, I think.

  It seems to me right now if you can get those figures to graduate =
smoothly you can really even out the feel.  Another question arises as =
to should we smooth out those figures between the sharps and naturals or =
let the sharps have a "lighter" number as they naturally do, because of =
their shorter length.

  Ed Sutton <ed440@mindspring.com> wrote:
    Vince-

    Never having learned calculus, I don't know how to work a formula =
like this.

    Assuming that I have
    -Strikeweight continuity within Stanwood's suggested range
    -Frontweight continuity within Stanwood's ceiling
    -Even and acceptable DW & UW

    How can I use this formula to improve action performance?

    Thanks!

    Ed Sutton
      ----- Original Message -----=20
      From: madelyn mrykalo=20
      To: College and University Technicians=20
      Sent: Friday, December 19, 2003 12:56 AM
      Subject: Re: Touch weight


      Hi-

      Of course you can have acceptable DW's & UW's and at the same time =
have a wide range of moments of inertia, some which may be acceptable =
and some which may not be.  Or the front weights could be too high.  =
That's why I don't think UW/DW alone tells us enough about how the =
action "feels". =20

      =20

      Here is a formula for moment of inertia (I):

       I=3D m1r12 + m2r22 + m3r32 + ... + mnrn2  =20

      =20

      Where m is the mass and r (radius) is the distance that the mass =
is from the balance hole of the key.  The key itself has some moment of =
inertia too.

      =20

      So the action in question (Wim's D) might weigh off acceptably (DW =
and UW), but also may have a too heavy a front weight, and/or moment of =
inertia.

      =20

      Stanwood has come up with a good standard of front weights.  =
Moment of inertia standards are a little more ambiguous at this point. =
More importantly is that the moments be reasonably smooth from key to =
key.





  Vince Mrykalo
  University of Utah


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