[CAUT] CAF

[Ed Sutton]

Add to this that as the lever approaches its top (rest) position, the spring 
is at its least compression (weakest).

When we set spring tension from the checked hammer, the spring is relatively 
strong because the lever is pressed down to its extreme position relative to 
the wippen.

In the freaky CAF, when the key has been released, but the jack can't get 
all the way back under the knuckle, the rep lever is just barely pressed 
down relative to the wippen. The lever can't quite lift the knuckle, and the 
jack can't quite make it back under the knuckle. A pianissimo blow will 
probably play, but a fortissimo blow will fail.

When we can set checking high, we can have somewhat stronger springs as 
well.

Ed S.


----- Original Message ----- 
From: "Ron Nossaman" <rnossaman at cox.net>
To: <caut at ptg.org>
Sent: Monday, August 17, 2009 5:39 PM
Subject: Re: [CAUT] CAF


> Chris Solliday wrote:
>
>> Lately since "firm but free" (or is it "as free as possible without 
>> making noise?") has taken over action center design this problem has come 
>> back. I repeat that it is not this simplistic and that other issues of 
>> friction and geometry must be examined and corrected as well. However, I 
>> believe that we can fix (in the absence of the balancier bridle)  most of 
>> the blame on "firm but free."
>
> I agree. Since we're using entirely the wrong indicator (hammer rise 
> instead of key rise) to set rep spring strength, free action centers force 
> us to set the spring too weak to avoid throwing the hammer up into the 
> string. The near zero let off, drop, and after touch trend doesn't help 
> this either. If we set the spring from key rise, which is it's function in 
> play, and pinned action centers to control resulting hammer rise, we'd be 
> in the center of functionality range. Then with the balancier height set 
> correctly in relation to the jack, let off, checking, and all the other 
> relative non-mysteries accounted for, and the shank close to the cushion 
> to do it's job, CAF wouldn't come up.
>
> How is it we seem to be getting back to having to rebuild every part in 
> every action to get the things to work? Maybe we should shoot at the other 
> foot for a while.
> Ron N