[pianotech] Action ratio measuring

[Ron Nossaman]

On 9/22/2012 9:27 AM, Al Guecia/Allied PianoCraft wrote:
> Clarifying question. Ron, as I understand it, your Key-in measurements
> starts at 20mm from end of key, whereas some are referring to a line
> from balance rail pin to the end of the key. Trying to get an handle on
> this. What am I missing here?

I put together what I thought made the most sense (to see if any sense 
was to be had here), and Del's comment about key top wear indicating a 
lot of finger traffic at about 20mm from the key front corresponds to my 
observations. So if that's where the pianist is feeling what we're 
trying to build, it seemed to me like a good key front measuring point.

There are so many different recipes, and I never had much luck with any 
of them multiplying leverage moments and ending up with something close 
to direct key down, hammer up proportional measurement. So I put my own 
together and tried it. It might well be a total fluke that it came so 
close to the physical direct proportion measurement on my action model, 
but it's one more recipe to try. I'm waiting to see if anyone else is 
curious enough to try it and either shoot me down, or verify that it 
sort of works.

A point on direct measurement: The shorter the key, the more critical 
the fore/aft point of dip displacement at the key. We're splitting hairs 
with a broad axe however we attempt this.

And I changed the subject to "ratio" from "ration"
Ron N