Action Geometry Consistency

[BobDavis88@aol.com]

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Bradley Snook writes:

> Every once in a while I come across a note where something in the action 
> geometry is obviously wrong (e.g. to get everything else correct, the blow 
> distance would need to be in excess of 1/8" higher/lower than the rest of 
> the hammer line).
>   
> What do I do to fix this problem?

The cause is almost always knuckle [roller] placement, as a tiny error has 
such a huge impact on leverage. If you're going to compromise, almost 
everyone will spot uneven hammer line, even though it is functionally 
probably not an issue. More pianists will find differences in letoff and 
aftertouch than dip, if you keep it within .010 or maybe a little more. At a 
certain point you've just got to fix the knuckle. 

In some cases, though, it isn't the knuckle that's misplaced - it's that the 
flange has been placed carelessly on the screw, especially on non-shaped-rail 
types. It can be as simple as moving the flange a little under the screw. 
There's often plenty of room in the screw hole. This may disturb the in/out 
line of the hammer, but you can decide at that point whether to correct or 
ignore that.
Bob D  

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