For anyone familiar with PianoDisc installations, what are your thoughts
regarding solenoid strike point on the keys?  The PianoDisc installation
manual says the optimum point is right under the capstans.  However, there
are other inferences in the PianoDisc documentation that say the strike
point should be as far back on the key as possible.  As you move the strike
point back on the key, the solenoid throw clearance, and the solenoid
leverage, increases due to the geometry of the situation.

It will be several months before I have a test system set up and have an
opportunity to run some experiments, but it seems that the optimum solenoid
strike point may actually vary from from one instrument to another.  It
looks like the PianoDisc solenoid throw range is about 1/2 inch.  The Grand
actions I am familiar with have a full dip clearance near the back of the
keys of about 7/16".  Uprights seem to be more like 5/16", with only about
1/4" full dip clearance at the capstan location.

Different actions seem to have different loading (touchweight)
characteristics. The solenoids are probably designed to provide a loaded
stroke that simulates a human keystroke when a current pulse of the correct
shape and duration is received.  Getting these two things together in the
right way probably has a lot to do with how well the systems perform in any
specific instrument.  I suspect PianoDisc has some drive current "pulse
shape" adjustment capability built into their electronics to allow for
differences in keyframe geometry and action loading ... but it also seems
that the strike point of the solenoids on the keys would have a lot to do
with how well the units perform.  Does anyone have any experience in this
area they would be willing to share?

Roger Stern on Bainbridge Island, Washington State.