[pianotech] Action ration measuring

[Ron Nossaman]

On 9/21/2012 8:21 PM, David Love wrote:
> Thanks Ron.  Question.  How did the jack knuckle contact point that you used
> compare to the jack center pin?  Were they close?

Nowhere near. Center pin spread was 99mm, where what I used was 82. I 
see I screwed up the description of wipout. It's a point on the wip 
beam, perpendicular to the point of knuckle contact, not level. My 
apologies.

It always annoyed me that the cumulative leverage of the presumed moment 
arms matched so poorly with Dale's 6mm in/out direct measurement. 
Something's wrong, and I'll take direct first. So this approach is based 
on perpendiculars to direction of travel. I know, it's rotational, but 
the rotational stuff is more suited to scholarly smoke generation and 
"dissembly" than practical math, because nothing rotates all that far. 
The hammer out is the exception, but then hammer mass is a really big 
part of the system, as I've tried to describe many times to the key lead 
removers. It seemed like a reasonable thing at the time. The surprise is 
how well it matched direct proportional measurement. I'd be interested 
in how this works on other actions and models. If you'd run it through 
yours and see how it matches, I'd like to see the numbers. This may be 
totally out to lunch, but it clicked pretty well with my model.

Ron N


> David Love
> www.davidlovepianos.com
>
>
>
> Keeping the measured levers close to parallel with one another, and the
> resulting force close to perpendicular to the levers - Try
>
> Key in: 20mm from front, along bottom to balance pin center Key out: balance
> pin center, along bottom to point below capstan position, perpendicular to
> key Wip in: center pin, parallel to wip beam to perpendicular line to
> capstan contact point Wip out: center pin, parallel to wip beam to
> perpendicular line to knuckle contact point Hammer in: knuckle core center,
> parallel to shank to center pin Hammer out: center pin to roughly center of
> mass of hammer
>
> With my old Teflon centered, felt knuckled Steinweigh action model, I get -
> sorry, no pretty formatting???
>
> Key In - bottom 20mm from end to bottom balance		220
> Key Out - bottom balance to bottom capstan position	114
> KeyRatio	1.93
> Wip In - capstan pos, level to flange center pin	65
> Wip Out - center pin level to knuckle contact point	82
> WipRatio	1.26
> Hammer In - knuckle core to center pin			16
> Hammer Out - center pin to center of hammer mass	130
> ShankRatio	8.13
> TotalRatio Distance Leverage	5.31
> 	
> 	
> Key Down at pin	6
> Hammer Rise	32
> Action Ratio	5.33
>
> Ron N
>
>