[pianotech] Regulating drop

[Richard Brekne]

I read in one of these posts that someone was under the impression that 
"drop effects nothing". I would suggest this is rather misunderstood.  
Drop is a necessary component to after-touch for one thing. And if it 
wasn't there the hammer would end up going past let-off height when the 
key is depressed fully.  You can easily enough accomplish this yourself 
by simply removing the let-off screw. With a close enough let-off and 
enough extra key movement after that point you end up quickly with the 
hammers on the strings after escapement.

The whippen has to hold the hammer firmly up... enough to avoid checking 
on a soft blow, enough to lift the hammer firmly upon release of the 
key.. or if you like push the hammer and the key in opposite directions 
in strong enough fashion to facilitate repetition. So it has to have a 
stop mechanism to avoid pushing the hammers into the strings after 
let-off. The drop screw does this but creates a touch component of its 
own in the doing.  Common practice has it that the drop screw and the 
let-off button engage simultaneously (or very very nearly so) because 
this evidently feels best to most pianists... that firm <bump> through 
let-off at the bottom of key motion. If both are regulated to engage 
simultaneously... and there is not too much after-touch key motion... 
then what Ed mentions is the result.  The hammer will end up virtually 
at let-off height when the key is very firmly depressed at the bottom of 
key dip.

I routinely run into regulation where some tech has regulated with way 
too much drop... this just slows every thing down and yields a rather 
squishy feeling to after-touch as the rep-lever has to engage far to 
early relative to the jack.  Drop effects quite a bit actually. Paul is 
on to it here.

Cheers
RicB


    If no-one else has said this, and I haven't seen it yet, my
    understanding of the purpose of drop, other than the secondary
    result of having a  visible let-off, is to "upstop" the repetition
    lever at the highest possible moment of rotation of the whippen and
    just before the sprung leverage  rotates in the opposite direction
    so that the jack is allowed to  return more efficiently under the
    knuckle. The more drop, a  greater compression of the spring, a
    larger "bounce" of the  knuckle on the rep lever, the less efficient
    return of the  jack, and the slower the repetition.
     
    Paul