1890s WNG Action Geometry

[David Love]

Yes and no.  Once you establish key ratio that that targets your weight
specs (at least within a range) you should always check to see if it
regulates properly.  Since action ratios relate not only to weight but to
distance, they will give you an indication of whether the action has a
chance of regulating properly.  All other things being equal, a 17 mm
knuckle will always produce lower friction.  You can manipulate the
convergence line by altering the wippen heal height, which in this case
Terry has to do anyway, and the jack alignment by moving wippen rail which
is quite easy on a Knabe action.  Different ways to skin a cat.        

 

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 Jon Page
Sent: Wednesday, July 19, 2006 4:16 AM
To: pianotech at ptg.org
Subject: 1890s WNG Action Geometry

 

>Move the dowel/capstan around until you achieve the balance weight you
want.

 

I have to disagree with this statement.  KR is optimally derived by
regulation parameters

not weight.  With a given knuckle radius, hammer bore, hammer blow and key
dip;

there is a KR which lifts the wippen through optimal distance.  That is, to
have the jack

in close proximity to the knuckle at full dip and not pressed into the rep.
stop felt or

bobbling on the knuckle.

 

Once ideal regulation specs are configured, you can manipulate FW to target
BW.

 

One would get a really low KR if one were to establish BW via KR with a
heavy SW.

 

Once you get the mechanism operating properly and the BW is too high,
consider

lowering SW, increasing FW or installing wippen assist springs.

 

Finessing weight is the polish, attending to the mechanics is the
foundation.

 

When I set up for new parts, key dip is known, hammer bore is known, blow
distance

is known. I select a knuckle radius and KR which produces the lowest
friction and BW

while producing an optimum regulation, it is a bit of a juggling act but a
decision can

be made by making regulation a priority.

 

Once the parts are installed and the action regulated, it's time to fine
tune the BW.

 

Hammer weight selection should be more of a consideration in BW than KR.

-- 


Regards,

Jon Page

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