[pianotech] accelerated action

[David Love]

I don't think they changed that--I assume you mean the feet supports for the
action rails.  The hammer flange center to string height is supposed to be
the same as the bore distance did not change.  They just removed the shoe on
the key and replaced it with the roller bearing in order to maintain the key
height.  That can sometimes cause some problems with keys that are too
flexible especially on the D (referred to as action saturation).  The
geometry did change with the accelerated action but it's hard to know what
was intended as they tend to be all over the place.  The early accelerated
actions had 16mm knuckle hanging and key ratios that were quite high in the
neighborhood of .56 or .57 (Stanwood method).  Combined with the new hammer
they started using which was considerably heavier than the hammers from
earlier eras these actions have a tendency to be very heavy.  

I don't see an issue with using a non accelerated action with post 1934 to
stack rails.  Some techs have, in fact, converted the accelerated action
back to the original shoe configuration (removing the roller bearing) in
order to alleviate the action saturation issue and have done so without
creating geometry problems or, I believe, having to change the stack height.
That's not to say that the stack height is always correct.  But that can
happen on any action.  

David Love
www.davidlovepianos.com


-----Original Message-----
From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of wjwallace
Sent: Monday, January 17, 2011 5:29 AM
To: pianotech at ptg.org
Subject: [pianotech] accelerated action

Hello Technicians,

I have a Steinway D from the early 1930's. A new Kluge keyboard was recently
installed. It is not an accelerated action, i.e. no half round. 

When Steinway came out with this accelerated action in the early thirties,
did they change  the top stack fixed rails to match the new accelerated
action? 

Was the geometry changed? What if any, is the downside of using a non
accelerated action with post 1934 top stack rails? Are there other
considerations? Whippen choices etc. Are there mixed views on this issue. 

I would be most grateful for a reply.

Bill Wallace