Action Geometry Consistency

[Bill Ballard]

At 11:10 PM -0500 5/14/03, Bradley M. Snook wrote:
>Bill, could you please explain [again] why pianists will not notice the
>discrepancies when they are placed in the key dip, but pianists will notice
>them when they are placed in the blow distance?

I'm not sure I said that pianists would notice the error if parked in 
the blow. (Unless they looked down through the strings and saw a 
kinky hammer line.) What I did say with some assistance from Terry, 
that what ever the error might be if left at the front end of the 
action (either dip or aftertouch), if left at the blow it would be 
multiplied by the action ratio.

>By how much do you vary your key dip?

I don't know. Once I've decided that I'm going to put the error into 
the aftertouch, I don't really care what the dip is. As I said, 15 
mils of error at the front of the key is ten times more noticeable to 
the pianist in the aftertouch than in the dip, which is why I put it 
in the dip.

I don't routinely measure it. However the next time during a 
regulation I see a bump in the line of LO buttons and jacks (a sure 
sign of some kind of SBR deviant), I can measure it. 1.) set 
absolutely equal dip between adjacent notes in disagreement (here's 
where I'd use a dead weight). 2.) measure the FR punchings removed or 
added to set absolute equal aftertouch between the two (here's where 
I'd use finger pressure).

>If I wanted to store all that excess in the key dip I would need to raise
>the key dip by .015"; there is a 1:1 ratio between key dip and aftertouch.

Agreed.

>That is WAY too much don't you think?

Not if it allowed you to achieve simultaneously straight-line LO, 
blow and aftertouch. Three out of four is not bad. The error has to 
be parked somewhere. As said before, 15 mils error in a .390" dip is 
3.8%. As far less dangerous place to park the error than the 
aftertouch, which is very noticeable to the pianist (they actually 
base their touch on it) and is far more important to deep, fast 
repetition than dip.

Way too much? 15 mils was just a "for-example" number.

>I've tried the finger pressure method, the problem is that I don't find that
>this method allows for any consistency in setting aftertouch.

We're probably doing it differently. You should describe your technique.

>In the end, however, I would feel much better if I could actually fix the
>real problem at hand.

My pianos are all perfect creatures, sounds like you've got a 
personal problem. <g> Seriously though, the list has give you some 
things to look for. When the problem doesn't fix, this is the 
bad-aid. I happen to prefer the solution which allows one to hold LO, 
blow and aftertouch steady. With the error so easily parked in dip, 
there's not reason to be looking at a ragged hammer line.

Bill Ballard RPT
NH Chapter, P.T.G.

"All God's Children got Rhythm"
     ...........Ivy Anderson in "A Day at the Races"
+++++++++++++++++++++