Re Strike Motion Ratio

[Kenneth Sloane]

                      Subject:                              Time:  12:36 PM
  OFFICE MEMO         Re Strike Motion Ratio                Date:  4/26/95

             -------DAVID STANWOOD'S POST-------

Dear Ken,

You mention in a recent posting that the speed of the
hammer with relation to the key is faster when pre-84
parts are used as opposed to post-84 parts, and that you
associate faster repetition with the pre-84 parts.

My comment:

In speaking of hammer speed, I have seen actions were the
contrary is true. It is apparently possible to have one
action with pre-84 Steinway parts that has a slower
movement of the hammer than another action with Post-84
Steinway parts.

When this happens it is because of a difference in the key
ratios of the two actions.  Key ratio can be defined as
the ratio of the downward movement of the key to the
upward movement of the capstan.

Key ratio is a thrashworthy subject.

            ------KEN SLOANE'S REPLY------

Dear David,

I did not say, "that the speed of the
hammer with relation to the key is faster when pre-84
parts are used as opposed to post-84 parts". What I did say was that there is
more movement of the key per unit of hammer travel with post 84 shanks. This
phenomenon can "slow down" the cycle of things that must occur for repetition
to happen, but it is certainly not the only thing that can affect repetition
and/or the speed of the hammer. Certainly another  thing is key ratio, and if
you'll recall, I suggested at the Sacremento convention that you incorporate
it into the formulas you use to analyze touch characteristics of an action. Up
until that point, your formulas paid no attention to it whatsoever.

A point of curiosity here. How are you measuring hammer speed?