Keep on filing...(picture attached)

[David Love]

Pinning the rep lever tighter allows for speedier jack return as well as
more positive hammer rise since the spring doesn't need to be set so close
to the fail point.  Most of the benefit, in my view, comes from the speedier
jack return and thus faster repetition.  

 

David Love
davidlovepianos at comcast.net
www.davidlovepianos.com 

-----Original Message-----
From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of Richard Brekne
Sent: Thursday, June 21, 2007 4:38 PM
To: pianotech at ptg.org
Subject: Keep on filing...(picture attached)

 

I dont think I understand the logic behind this claim.  Whatever friction
there is at the lever pin simply restricts the amount of movement of the
lever for same spring strength.  I suppose more of the springs energy might
be directed to jack return... not really sure about this either when it
comes to it.

The rep lever springs upwards and downwards with equal strength regardless
of the tightness of the pinning. The only thing that can change the relative
pressure between up and down would be a repositioning of the pin... i.e.
changing its leverage moment.

I would suspect, that 8-10 grams works well because it fits well with the
multi-tasking between the rep spring and other related parts... ie jack
return, hammer lift, appropriate friction levels for centers belonging to
these...etc.

Cheers
RicB


Pinning the repetition lever to 8 grams restricts the jumpiness of the
hammer on key release and directs more of the spring's energy into
returning the key.  When I'm doing a very careful regulation of a
performance piano (where "it's so even" is the compliment I want to
hear) I use an 8-gram weight I have that has a hole in the middle.  If I
put that weight on the screw that regulates the rep. lever's height (the
short end of the rep. lever) I want the pinning tight enough that it
holds the weight.  When I place it on the drop screw pad (the longer end
of the rep. lever) I want the lever to gently fall.

dp

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