Key return speed

[Stéphane Collin]

Thanks, Ed.

This was very informative.
Now, imagine an older english action, with no wippen, just a jack that sets 
off and then the hammer goes in check, and at that moment, there is nothing 
that pushes the key back home.  Say that this particular action is too slow, 
how would you cure ?  You talked about the moment when the key inertia takes 
the control of return speed.  Would more lead at the rear of the key make it 
return faster ? Or opposite ?  I'm hesitating between notion of weight at 
the rear of the key (that I suppose to make it get down quicker) and notion 
of inerty (that I suspect to make the change in direction of move of the key 
slower).
What do you think ?

Best regards.

Stéphane Collin.



----- Original Message ----- 
From: <A440A@aol.com>
To: <pianotech@ptg.org>
Sent: Tuesday, January 24, 2006 10:55 PM
Subject: Re: Key return speed


> Stephen writes:
>
> << I'm clearly convinced that the return speed of the key is one of the 
> most
> important features for control and repetition, but I wouldn't know how to
> improve that speed in an action otherwise well regulated.
>
> Any thoughts ? >>
>
>         Repetition is determined by the speed of key return, and how far 
> it
> has to go before the jack resets under the knuckle.  The latter is 
> determined
> by back check height.  The former is a combination of spring strength, 
> (which
> needs not be stronger than what it takes to raise the hammer just slower 
> than
> what you can feel in the key), how much weight there is in the key, and 
> what
> the leverage ratio is between the whippen and key.
>    It is this last that can make a huge difference!  We cannot
> indiscriminately change the action ratio by moving the capstan closer to 
> the balance rail
> pin without slowing the action up.  There is a maximum ratio limit before 
> the
> inertia of the key becomes the controlling factor in its return speed.
>   A tighter balancier pinning will allow more spring strength, but if you
> get over 9 grams, it may also slow things up.  The more aftertouch there 
> is, the
> farther the key has to go to reset, also.
> regards,
>
> Ed Foote RPT
> http://www.uk-piano.org/edfoote/index.html
> www.uk-piano.org/edfoote/well_tempered_piano.html
>
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