Key Pin Friction - was Heavy Playing S&S C

[David Stanwood]

Farrel writes:

>And then how do techs evaluate key pin friction? I have never seen anything 
>in print regarding any definitive procedures to evaluate key pin friction.

Terry,

I published the method in the PTG Journal in my atricle:

"Standard Protocols of the New Touchweight Metrology"
PTG Journal February 2000

Excerpt:

"The new measurement called Key Friction Weight (KF) tells us precisely how 
much of the Friction Weight is from the key bushings. Place the key on the 
front weight jig and follow the protocol for measuring negative Front Weight 
(FW).  With the key on the jig, place temporary weights on top of the key 
and slide them back and forth until a position is found that makes the Front 
Weight (FW) zero.  Then, without disturbing the position of the temporary 
weights, place the key back on the key frame and push the back of the key 
down onto the back rail cloth. Then find the minimum amount of weight placed 
on the front of the key at the Measuring Point that causes the key to drop 
(Fig 8).  Another way is to place the key on the frame and attach a key 
leveling lead to hold the back of the key down. Then measure Up Weight and 
Down Weight (with stack off) and apply the formula (DownWt - UpWt)/2.  The 
value found is Key Friction Weight (KF)."

Newton... taking three grams off the strike weight takes it down and out of 
the concert weight (High) zone.... I would not recommend that although it 
will make the action feel better after taking out loads of lead....

Tone is the primary concern... touch is secondary.  In nice pianos both are 
nice....

David Stanwood


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