[CAUT] Subservience, was CAF

[Richard Brekne]

Hi Mark...

I think we can all agree that reasonably close cushions is a good thing, 
regardless of how we look at this CAF thing.  As to the variance of 
opinion about CAF... I am wondering just how much of that is rooted in 
just how much key kickback each of us find acceptable.  I know techs for 
example who will have none whatsoever. These usually are also techs who 
like a very very slow rise from check to drop when setting rep spring 
tension.  This kind of set up is in my experience a recipe for sluggish 
repetition, and coupled with a long distance down to the cushion from 
the shank I can see where one could get into CAF problems.

For myself... I like pinning on the jack and rep lever to be fairly 
tight, allowing for a strong spring when the rep spring is set to the 
<<immediate rise>> from check to drop. Just short of a hop I guess you 
could say....  This can definitely be felt in the key.... if you feel 
for it... but I've never yet heard a single pianist comment anything 
that went in the direction of key kickback... so I don't see it as an 
issue..... and yes, I do keep my ears open for comments that go in that 
direction.

Anyways... such a set  up is going to repeat period. Good high checking, 
15-12 mm or as close as the back check / tail will allow without 
dragging on a fff blow... minimal aftertouch seen from the perspective 
of total jack travel...  rep lever correct to jack top height.... all 
the basic regulation bits in place... and I just dont see the cushion 
being needed for anything but a system stress reliever for very hard 
play...

Thats my take anyways....

Cheers
RicB


    Thanks Ric,

    A number of years ago I was working through this on a C-3 action at
    the Banff Centre; Repetitions failing the "wink" test was the
    problem, re-pinning them turned out to be the solution.

    I was bothered by having to repin these centers to 8 or 10 grams,
    when we had a service bulletin posted over the re-pinning bench that
    clearly suggested they be 4-5 grams.

    So, my good friend and colleague Denis Brassard asked me why we
    treat this center like the centers within the action? After all,
    their range of motion and dynamic operation is really quite different.

    That got me thinking about it in a different way.

    So now we re-pin repetition centers quite routinely, and without
    very much religion... i.e.: often pushing out the original pin with
    the next over sized, and a quick friction test.

    I'm happy doing this, and ever since have yet to encounter a CAF
    situation that addressing hammer/whippen centers and spring
    arc/tension won't solve.  

    Or, in your words... "CCJUNMWYDTWRF is something I just dont run into."

    best,
    Mark C.

    PS I confess to changing rebound cushions more than once for
    appearance sake alone, but also believe they should be very close to
    the hammer shank at rest.