aftertouch/front rail punchings

Delwin D Fandrich pianobuilders@olynet.com
Sun, 29 Mar 1998 10:46:11 -0800


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A440A wrote:

> Dave asks:
> <<am I the only tech who sets the dip in the sharps as equal aftertouch to
> the naturals? >>
>
>     I set the aftertouch to be consistant.  If the keydip is to be even, then
> usually the hammerline has to be sacrificed.
>    On the closest regulations,  I set the keys with a consistant measured key
> dip, then, as I set aftertouch, if a key requires more than .010" alteration,
> I move the hammer to compensate.  This splits the difference of geometry
> inconsistancies between key travel and hammer travel,  a lot of work, but
> there are some players out there that home right in on it.
> Regards,
> Ed Foote

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But what is it they are homing in on? Are you sure it is aftertouch? In the work I did, lo
those many years ago, I really didn't find anyone who actually felt the slight variations
in aftertouch -- and I do mean slight -- if the other parameters were absolutely
consistent. At least not in any real world performance situation.

In other words, if the hammerline/blow distance was accurate & consistent, the letoff
distance accurate & consistent, the jacks properly set and the repetition lever height
correctly set to the jack, the backchecking consistent, the repetition lever upstop screw
set properly, and perhaps most of all key travel precisely set. Yes, including the sharps.
(So, did I leave anything out?) It seemed to me at the time that what they did feel were
even slight variations in key travel -- i.e., key dip.

If there were variations in action geometry that were significant enough to affect
aftertouch by some noticeable amount, they needed to be fixed prior to beginning final
action regulation. And there often were. Usually they were traced to improperly installed
knuckles. It was a fairly easy matter to pop the offender(s) out and glue it(them) back in
properly. In fact, with the actions found in the new pianos I worked on in that era, this
was a fairly common task and was done before the actions got even their first shop
regulation. It is usually taught that the jack should be aligned to the knuckle. The
problem with this practice is that the key/hammer lever ratio becomes a variable. A better
practice, then, is to set the tips of the jacks in a straight line relative to the average
knuckle c/l and then reset the wild knuckles so that they are properly aligned to the
jacks.

I tested this notion only a few times -- and then it wasn't what you could call a
thoroughly scientific test, just enough to satisfy my personal curiosity -- by setting up
actions as precisely as I could and then varying the jack letoff point. Except under very
soft key strokes no one really noticed much difference. And then it was because some
hammers didn't have enough momentum to carry them through letoff. Their motion would stop
before they were able to impact the strings if the letoff point was set too far away from
the string. In other words what the pianists noticed was that there was no sound. At the
time I didn't try varying the hammer blow distance which would have introduced other
problems. Also, I didn't think of it.

So, has anyone else actually tested actions in this way? If so, how? What was the
procedure used.

One more point:
In my earlier post I probably should have made more of a point of the fact that uniform
key height and level is absolutely essential to this process. And yes, that includes the
height and level of the sharps. Sharp leveling and travel distance (dip) should receive
just as much attention as is lavished on the naturals. In setting key level it also helps
to have thin and firm felt punchings. Leave the thick felt punchings for pedal pin
bushings or something. It is also helpful to use more thicker paper punchings and fewer
thin punchings if possible. As well, it is helpful to have fairly thin and firm key back
rail felt.

Regards,

Del

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