[pianotech] Damper tray block

[Jon Page]

Having the underlevers (u/l) parallel at rest would still add sliding 
friction only it would also be crushing the corner of the felt when 
lifted. As far as the magic line goes, it might look good on paper but 
has limited effect. You might say it is the difference between Theory 
and Practice.
The difference between Theory and Practice is that in Theory there is no 
difference but in Practice there is.

I shoot for the least friction and have relieved the friction which felt 
is at the key front by simply altering the angle of the u/l's.
The least amount of sliding friction is when the u/l is lifted to 
parallel with the keybed.

Regards,

Jon Page
____________________________

  I also like to make the arcs described by key and underlever share 
some of that magic line thinking.
I suppose minimal slide would require that the contact point be on the
magic line at half stroke, but I question whether it makes much
difference if it hits the line at the end.
        It seems that having the underlever horizontal when at rest would
apply the maximum weight on the string, and cause the sliding action to
less than that which occurs when the underlever is sloping down.  I
don't know that there is room to lower the tray that much in most
cases, so I also often leave them as Jon mentioned.
     Does anybody smooth the wooden contact point on the underlevers
with, say, 400 grit paper and a spray of Teflon ?? Maybe, even
burnished graphite??   Just asking,wondering if there is anybody else
out there that has run out of things to try........
Regards,  Ed Foote RPT