simple question

[Farrell]

I will be referring to the forward side of things (side that the pianist is on) and the back side of things (side the piano belly (soundboard) is on). The back face of the jack should be in the same plane as the back face of the wooden knuckle core - or at least the back edge of the end of the knuckle core should be aligned with the back edge of the top of the jack. I think in the design phase of the action, indeed the little scribed line in the rep top is where the back edge of the jack top should be, but in practice it is often displaced - don't rely on that mark, it may be right on, it may not be.

Adjust as above, and then play the note slowly and watch the jack and knuckle contact. It actually make a fair bit of sense. Placing the jack as described above provides for adequate safety factor for the jack to stay in place securely to propel the knuckle/shank/hammer upward - but it is not so far under the knuckle that the jack slips out on a hard blow.

Set it up so it works nicely, then slowly adjust the jack so that it sits closer to the pianist at rest. Try firm blows to the key. You will see that just moving the jack a little bit forward will cause the jack to slip out from under the knuckle during a hard blow - and no note will sound. Place it back too far, and all will work, but the let-off event of the keystroke becomes a laborious event.

Often a good way to determine where something should be adjusted is to experiment and see what does not work. The jack postition responds well to this type of experimentation.

Terry Farrell
  
----- Original Message ----- 
From: "Gerald Posey" <poseyviolins@charter.net>
To: <pianotech@ptg.org>
Sent: Tuesday, March 19, 2002 3:18 PM
Subject: simple question


> At least I hope it is.  In the action, with everything at rest, should the
> jack be centered under the knuckle?  All the repetition levers have a mark
> scribed into them that corresponds to the center of the knuckle.
> Thanks,
> Gerald
> 
>