upright touchweight

[John Tonyan]

Again, my big questions are, how do I increase the friction in the upright 
action and can I do it without adversely affecting performance? If this were 
attainable, it seems the inertia in the keys would be easily resolved.

Yes, the keys need a predominance of weight in the rear, but once an 
acceptable DW/UW were achieved, key inertia could then be adjusted by adding 
a front and a rear lead at equal distances from the balance rail, giving the 
pianist the inertial-resistance that is desired when playing at forte - as 
opposed to just a static measurement of DW/UW which isn’t concerned with 
inertia.

I understand how the springs in the upright action affect the touchweight, 
but that doesn't affect the friction. What I am really looking for is that 
silky movement of the key that you find in a grand when the DW is 50 and the 
UW is 25.

I know this is not impossible in an upright; I have measured actions that 
have performed this way, but I haven’t studied them.

The only time I saw the Fandrich upright was long before I was doing 
touchweight work. Would that action shed any light on these questions?

Thanks,
John


Original message.

     Hello all.

I need some help with upright touchweight. I’ve searched the archives, with 
little gain.

I redesign grand touchweight on a regular basis, incl. leverage, friction 
and mass. The wonderful results I gain there leads me to want to understand 
the upright action better, especially for the sake of many gifted students 
who lack the resources to invest in a grand.

For example, a Samick upright, JS 115:

Downweights 	40-45gr
Upweights 	30gr
Keyleads	Bass 1 lead, 2” behind balance rail
		Mid  1 lead at back of key
		Treb 2 leads at back of key

My biggest question: Is it possible to widen the difference between the DW 
and UW (friction), or do you just shoot for an acceptable Balance Weight?

What do you do about the inertia of the keys? For feel, we should have more 
inertia in the bass than in the treble. It should be contiguous, therefore 
the butt springs would have to be adjusted after the keys are leaded.

I’ve considered double-leading the key (front and rear) to increase inertia 
in the bass without affecting the static touchweight, but would that affect 
repetition speed?

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