upright touchweight

[ed440 at mindspring.com]

John-

The vertical keys must be back weighted to be sure the keys fall back and the wippen drops enough for the jack to reset.  The inertia that matters most is that of the hammer head.  I suggest you explore increasing the hammer weight by adding a paper clamp or small loop of solder wire at the top of the hammer shank.
Static measurements aren't going to help much here. Add a little bit of weight to the hammer, play, feel and listen.  A small amount of added weight may produce a notable change in the sense of control in playing a vertical, and it also may give the instrument a warmer voice.

Ed Sutton

-----Original Message-----
>From: John Tonyan <tonyanj at hotmail.com>
>Sent: Dec 18, 2006 4:27 PM
>To: pianotech at ptg.org
>Cc: tonyanj at hotmail.com
>Subject: upright touchweight
>
>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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