Knuckles

[Michael Jorgensen]

Richard Brekne wrote: The jack

> moves in both directions across the knuckle...so which direction it
> needs the smooth run, and why this is so

Rough moving toward the flange and smooth toward the hammer.
This is supposed to give better grip for the jack so it doesn't skip out
(cheat) as easily, and smooth toward the hammer should make it less
resistant for easier jack return.  Since the fingers of a pianist are much
stronger than a rep/jack spring they are better able to overcome the
friction caused by this roughness.  I believe that some European Pianos
reverse the nap direction with the thinking that it makes a smoother feel
for the pianist and possibly quieter.
-mike