[CAUT] Repetition ( was Steinway center pin height)

[A440A at aol.com]

Inre actions suffering catastropic action failure, 
Ric writes:
>>one thing nearly all replies have alluded to is a 

situation where the shank is resting on the cushion.... and at the same 

time resulting in a condition where the jack can not get under the 

knuckle if it was not already under there to begin with.<>two problems. 
First... the jack is supposed to be 

under the knuckle well before the the shank even gets close to the rest 

position after play.  If it doesnt.. then either the rep lever spring is 

too weak, or the center may be to tight.. or the jack is regulated too 

far out... similar things.<< 

      Any action will fail to repeat if the second note is struck before the 
key resets under the knuckle.  There is a minimun distance the key must be 
allowed to rise before the reset.  If the key is struck before this minimum 
distance is achieved, the jack will either skip or will not touch the knuckle, at 
all.  On a normal action, this is just a one time failure and as soon as the 
key is allowed up, the note will once again repeat. 
       On an action in which the hammershank cushion is too far below the 
hammer's resting position, the skip, (cited above) allows the hammershank to fall 
so far that the capstan is holding the whippen too high for the jack to 
reset.  In other words, the knuckle is below the lowest jack height possible.  
Hence, a note that doesn't play until the hammershank is bounce up into the jack's 
range.  
       ( I hope that makes sense...)  
 

<<  The rep lever is supposed to lift the hammer 

via the knuckle up to a position where the jack can slip under as soon 

as (nearly immediatly after) the key is released.  >>

       I must respectfully disagree.  The purpose of the rep lever is to 
increase the speed of the key return.  We measure the spring strength by watching 
the hammer rise, but in rapid repetition, that event doesn't occur.  Under 
fast repetition,  the hammer shank doesn't rise between blows, but rather, stays 
at checking distance while the key and whippen, (under the influence of the 
spring), return to their "reset" position.  One can ascertain this for 
themselves by playing middle C so that the hammer is held in check, and then slowly 
depressing B3 so that the hammer is at drop.  Simultaneously, release both keys 
and observe that the C return far, far more rapidly than the B.  
      One can also see, on an action model, that when the key is released 
while the hammer is held in check, the hammer doesn't rise, but rather, drops to 
its at rest position. Under high speed conditions, there is no time for the 
hammer to rise between notes. 
     This is why there is no difference in repetition speed between a spring 
that slams the hammer off the jack when released and a spring that simple 
lifts the hammer as fast as possible without being felt in the key. Unfortunately, 
many regulators destroy the sensitivity of escapement by pursuing the former 
course in the mistaken belief that it improves repetition.   Checking height 
has far more effect on repetition speed than anything else.

Regards,



Ed Foote RPT 
http://www.uk-piano.org/edfoote/index.html
www.uk-piano.org/edfoote/well_tempered_piano.html
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