[CAUT] Gram Tension Guages

[A440A at aol.com]

David  writes:

<< Baldassin says grams matter most because of the touchweighting issues
involved and he feels it produces a more consistant feel in the action.
Teel says it's a functional process and if it doesn't swing consistently
it won't feel consistant.<< 

   Greetings, 
      I use the swings. Tapering their number through the scale, as well as 
compensating for humidity, is very straightforward.  It is also easier to 
determine, in the field, if a flange is out of line, or not.  For normal 
regulations, it is simple to swing the whole stack and repin the loosest 30% and the 
tightest 30%, and get a hammer line that is consistant enough for any and all 
practical purposes.  The pinning doesn't stay exactly where we leave it, anyway.  
     My logic for counting swings is because in actual use, the pin is 
bearing quite hard against one side of the bushing cloth, distorting it. ( If you 
want an idea of how much, just put a full length pin through the hammer shank 
bushings, without the flange.  Then, place the shank so that the knuckle is on 
the very edge of the table with the hammer suspended out in the air, and then 
press down on the ends of the pin so that you lift the hammer.  You will notice 
a lot of pressure on your fingertips! This is the same pressure that is 
resting on the top of the hammer flange bushing when the knuckle is supported by 
the jack/balancier.  
    While the bushing is so distorted,   the friction is not being provided 
evenly all the way around the circumference of the pin, but rather, by the 
smaller arc that is under pressure. Keep in mind, this is a static test, and the 
pressure is much greater on that small arc when the key is given a hard blow.  
I know, friction is a function of velocity, but it is hard to tell if the 
small arc, under the heavy pressure of a fast blow, creates as much friction as 
the full circumference does when slowly moved.  
    While swinging doesn't compress the felt nearly so much as a note played, 
it is closer to real life application than the slow measurement of a gram 
gauge.  I  do know that swinging the parts is much faster when pinning, and when 
the swings are consistant, the overall action consistancy is more affected by 
other variables, such as hammer mass, leverage, friction at the key and 
balancier,etc.  
 Regards,  

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