upright touchweight

[John Tonyan]

Hello all.

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

I redesign grand touchweight on a regular basis: 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?

Many more thoughts and questions on the subject, but this would be a good 
beginning.

Thanks.
John Tonyan

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