[pianotech] Measuring Action Ratios

[David Love]

Yes I did!  Where to measure from and to seems to be a subject of some
debate.  I'm aware of the other protocols and there are others besides the
one you mention.  The discrepancy isn't to do with where I'm measuring from.
It is very unlikely that this action has a 5.2 ratio as measured by the key
travel/hammer movement method.  The 5.87 that I got from this lever arm
measuring is consistent both with how the action regulates and the weight
based formulas (Stanwood) that I use for determining strike weights with
targeted balance and front weights , (not to mention how many of the older
MH actions were set up).  

I have tried every method that I know of for measuring action ratios
(including the one you mention) and this one I find the most reliable and
consistent with the weight formulas as I use them and regulation
predictions.  

In this case the key travel/hammer travel relationship is not consistent
with the actual action ratio no matter how you measure it.  That is the crux
of the matter.        

David Love
www.davidlovepianos.com


-----Original Message-----
From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of Jim Ialeggio
Sent: Wednesday, January 16, 2013 4:39 PM
To: pianotech at ptg.org
Subject: [pianotech] Measuring Action Ratios

David Love wrote:

<Shank Ea is measured from the hammer flange center pin to the center of the
knuckle core (measured along the shank) .
<Shank Ra is measured from the hammer flange center pin to the center of the
hammer molding (measured along the shank).

Did you mean to write this David???

Shank Effort arm, or in my terminology shank lower lever, is center pin to
full projection of knuckle...center pin to full projection of the knuckle is
the hypotenuse of a right triangle rather than the adjacent side you called
out.

LIke-wise, Shank Resistance arm, on in my terminology shank upper lever, is
shank center pin to strike point on the hammer. Again, it is a hypotenuse,
of a right triangle, rather than the adjacent side you called out along the
shank.

Perhaps this is what is messing with your numbers???

Jim Ialeggio

-- 
Jim Ialeggio	
jim at grandpianosolutions.com
978 425-9026
Shirley Center, MA