Re: Stéphane Collin

[Stéphane Collin]

Thank you Ed, for taking time.

I have to digest all this.  Yummy !

Best regards,

Stéphane Collin.

----- Original Message ----- 
From: <A440A@aol.com>
To: <pianotech@ptg.org>
Sent: Wednesday, September 18, 2002 2:50 PM
Subject: Re: Stéphane Collin


| Stéphane Collin asks:
|  
| >> Am I right assuming that the more drop, the more and for
| >  longer time friction between the jack and the knuckle ?  
| 
|     The jack is in contact with the knuckle from the bottom of the hammer 
| blow to the point of let-off,(and even then, the distal side of the jack may 
| lay against the proximal side of the knuckle, but that is not usually a 
| factor in the feel).  
|     After the drop button contacts the balancier, the jack has sole support 
| of the knuckle.  On a hard blow, this is not felt, on the softest, you may 
| find that the later the drop screw engages, the less friction there is upon 
| let-off because the balancier is holding up part of the weight while the jack 
| is pulled out from under the knuckle,  ( on many actions, you can actually 
| play a note very softly with the jack removed, so the balancier CAN carry 
| some of the weight all the way to escapement).  
|    Having the drop set too low will create a larger zone before let-off where 
| the pianist must play against repetition spring resistance. This will 
| certainly interfere with pianissimo control, particularly when playing rapid, 
| soft passages.  
|  
| > While we are on that subject, do you regulate let off by
| > feel also, or with a gauge ?
| 
|   I regulate let-off by finding how close the hammer can be brought to the 
| maximum excusion zone of the string without touching it.  That is why let-off 
| is greater in the bass.  
|  
| >> Just another thaught : I sometimes feel that good touch
| > feel is playing against good performance.  I.e. : I think I
| > can achieve much better repetition when reducing aftertouch
| > (but loosing the good feeling of the notch).  
| 
|   The speed of repetition is determined by how far the key must travel back 
| upwards to allow the jack to reset, and how fast the key moves.  The distance 
| the key must travel is determined primarily by the hammer-checking height.  
| If one reduces the aftertouch by reducing keydip, the key has less distance 
| to travel before the jack resets, but it is hard to change keydip too far 
| away from 3/8".  You will also notice that, all other things being equal, as 
| you reduce the keydip, you lower the checking height, so this is 
| counterproductive to repetition speed.  
|     The difference in key return speed between a very strong spring and one 
| that slowly lifts the hammer from check is minimal, so excessive spring 
| strength only creates extra resistance at let-off,(via the drop resistance 
| and to a lesser extent, the jack's resistance).    
|     A soft spring, jacks positioned as far proximal as possible without 
| skipping, knuckle resting on both jack and balancier,  let-off and drop set 
| to just clear the strings excursion zone, checking at maybe 1/2" to 3/8", and 
| no more than .035" aftertouch will generally give you maximum ease of 
| escapement with the fastest repetition that the action is capable of.  
|    There are always qualifications.  Action ratios can affect rep speed, 
| particularly when the capstans are brought closer to the balance rail.  This 
| is due to the moment arm that the hammerweight has at its disposal to lift 
| the keyweight.  While moving the capstans closer to the balance rail will 
| often allow either heavier hammers or less lead in the key, there is a point 
| of diminishing returns after which repetion speed will be poor, regardless of 
| weights on either end of the equation.  
| Regards, 
| Ed Foote
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