[CAUT] S & S D rest cushions

[Fred Sturm]

On Aug 16, 2009, at 1:15 PM, Richard Brekne wrote:

> I just cant see CAF (as defined by Fred a couple posts back) getting  
> into the picture. Try as I might with my action model... I could not  
> find a way of causing this lock up in any way at all given  
> reasonable action regulation, and good friction levels for centers  
> and key bushings, even with the rest cushion totally removed.  Nor  
> have I ever experienced being forced to deal with the rest cushion  
> distance to fix any king of jack missing problem at all in real  
> piano situations.


	I'm not surprised you can't reproduce it on a model. It seems to take  
a rare set of circumstances for it to happen. When I first ran into  
it, a pianist left a note after rehearsal, saying notes X, Y and Z  
were having repetition problems sometimes. I checked them, found  
nothing amiss, did the usual odd bits of things to optimize repetition  
(regulation, spring tension). Dress rehearsal, and the pianist called:  
"I'm still having repetition problems with those notes, and it is in  
very obvious places" (can easily be heard by the audience). So I went  
into the hall and had her show me. Yep, no question there were  
problems. After watching and listening to what she did, I was able to  
make it happen. I'm not sure I could do it again at this point, but I  
could do it consistently at the time. It had to do with precise timing  
of a second blow on the key, as well as the precise way the first blow  
was executed (pretty hard and staccato). What seemed the easiest  
solution was tacking a bit of felt onto those cushions. Presto!  
Problem solved. (All shanks were a good cm or more above the cushions).
	Since then I have heard a number of fellow techs describe the same  
thing. Within the past 3 - 5 years, at a NYC Steinway Academy session,  
Eric Schandall mentioned that you needed to be sure the shanks were  
close to the cushions, as otherwise a certain kind of action lock up  
could happen. Sounded like exactly the same thing.
	So, be my guest, believe it or don't believe it. You may or may not  
ever run into the problem. But it is not just my own personal  
imagination. It is a hallucination shared by others. And anyway, it's  
a good idea to have that distance close for other reasons, partly as  
described in my last post and by David Love.
Regards,
Fred Sturm
University of New Mexico
fssturm at unm.edu