[CAUT] S & S D rest cushions

[Andrew Anderson]

Have to agree with Fred here.  I experimented with the rep springs and  
had to choose between bobbling hammers at mp play or bolstering the  
whip cushions with additional cushion felt tack glued to the original  
felt.  I did this after advising the customer that the previous hammer  
install had been severely botched and that the action would benefit  
from a total rebuild.  They went for the cheap fix and were delighted  
with it.

Andrew Anderson

On Aug 14, 2009, at 4:05 PM, Fred Sturm wrote:

> On Aug 14, 2009, at 2:04 PM, Jeff Tanner wrote:
>
>> "Catastrophic Action Failure" happens because checking is too low,  
>> hammer flange, jack or rep lever pinning too sluggish or rep  
>> springs doing absolutely nothing at all.  Not because of rest  
>> cushions.  We shouldn't even need rest cushions or rails.  I've had  
>> the same issues with hammer shanks having to be so high above the  
>> rest cushions to get aftertouch with reasonable keydip and never  
>> one issue of catastrophic action failure unless one of the above  
>> was the cause.
>
>
> 	Maybe you haven't experienced it. I have (with all those other  
> variables within good parameters). It happens with specific types of  
> playing, and is rather rare, but it can be a "catastrophic" problem  
> when it occurs in a concert. It has to do with specific timing of a  
> hard, staccato blow and what happens to the key following the blow.  
> Sometimes it is a matter of a fairly rapid repeat, sometimes just a  
> matter of the key not let up all the way before the hammer has  
> completely rebounded (the key keeping the wipp in a somewhat up  
> position). In any case, the result is a jack jammed between knuckle  
> and rep window cushion, which the rep spring can't overcome, I guess  
> because of geometry. I have had the complaint, have asked for a  
> demo, and have been able to reproduce the symptom. The only cure was  
> getting the cushion closer to the shank, and it was definitely a  
> cure. This after checking all those other parameters.
> 	Ask Eric Schandall, he's had precisely the same experience and  
> strongly recommends that cushions be very close to shanks. I expect  
> Kent Webb would tell you the same.
> 	"We shouldn't need rest cushions or rails" is a rather naive  
> statement. There are, actually, reasons manufacturers include them,  
> this being one of them.
> Regards,
> Fred Sturm
> University of New Mexico
> fssturm at unm.edu
>
>
>
>
>

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