Knabe(Samick)/Renner & the 114 mm action spread

[Ron Overs]

>Wow!  Doesn't that mean practically no aftertouch?
>
>I try to set the jack so at full dip it's in the middle of the rep window.

Hello Cy,

Not really. There is quite some variation between the amount of after 
touch which technicians shoot for. In general, I don't like to see 
too much clearance between the jack and the knuckle when the hammer 
is in check. But it is important that there is some clearance. For 
domestic pianos which don't see a technician too often it is better 
to allow for a little more clearance than for a concert or 
performance instrument which might have the reg touched up every 
couple of months or so.

For faster repetition, less clearance is required between the jack 
and the knuckle at the check position. Clearly, if a domestic 
instrument is set too fine, there is a risk that the blow distance 
will widen between service intervals such that the knuckle clearance 
might reduce to zero, which might cause blubbering at let-off during 
soft playing.

I would also say that if the cushion touches the jack before it 
clears the knuckle then the felt needs to be trimmed to reduce its 
thickness or replaced. With our own grand piano action, we've found 
that the small variability which occurs between production batches 
can result in the jack stop felt being too thick or too thin, 
depending on the setup of the machines during manufacture. There 
shouldn't be any difference from batch to batch, but in practice its 
hard to control. Very often we will change the jack stop felt to 
achieve the clearance we're looking for.

Its an interesting area of piano work, this setting up of actions. 
There's always something more that we learn as we live for longer.

Ron O.
-- 
OVERS PIANOS - SYDNEY
    Grand Piano Manufacturers
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Web http://overspianos.com.au
mailto:ron at overspianos.com.au
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