[CAUT] balancier/wippens report

[A440A at aol.com]

Wim writes: 
<< But when it comes to having hammers checked, there are no 

measurements. The curve of the tail, the rake of the back check, the 

roughness of both the tail and the backcheck, the strength of the 

spring, and the amount of touch, all have an effect on how a hammer 

checks. But there is virtually no way of measuring these things. >>

        Au contraire!!  The curve of the hammer tail should be near half the 
swing distance.  Some techs like a little longer for a flatter curve, but 
don't exceed 3 inches.  The rake of the backcheck should be right about 10 degrees 
away from parallel to the hammer core line.  The spring should be as strong 
as you can make it without feeling it in the key, ( a very slow rise will work 
well with just about every piano, but doesn't leave a lot of room for error 
under changing climate conditions.  However,  the hammer rise is only an 
indicator of spring strength, the spring's action, under fast repetition is against 
the key, since the hammer doesn't move until the jack resets. ).  
  The amount of touch I like is no more than .030" after the jack escapes.  
If all these things are in place, and your pinning and friction are within 
bounds, the roughness of the tail is almost inconsequential.  
Regards, 



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