Knuckle Rep Lever Magic Line

[Phillip Ford]

At 08:51 AM 1/22/03 , you wrote:
>In my limited experience of checking the "Magic line" at the knuckle I've 

>noticed that even on the best of actions the only time the knuckle gets 
>close to the line is at the very end of the key /action stoke.  (I think 
>Ron Overs action is the exception.) So maybe the parameter is , that the 
>closer the knucle is to the line the better.......
>
>    Somebody else jump in here and tell me something I might be missing.
>       Dale Erwin
>
>

I know it's akin to heresy to suggest this on this list, but do you think 
the fact that the best actions (in the opinion of pianists) are set up
this 
way might mean that there's actually something to it?  Or is it just more 
outdated thinking by manufacturers stuck in the past?

Setting up the geometry so that the jack-rep lever contact point is on the 

'magic line' at half stroke should result in lowest overall friction 
between knuckle and rep lever.  If the only purpose of an action was to 
last as long as possible then this would be the obvious choice for how to 
set things up.

Setting up the geometry so that the contact point is on the magic line at 
the let-off point results in the top of the jack moving perpendicular to 
the direction of knuckle travel at the last moment of contact between jack 

and knuckle.  This should mean maximum power transfer from jack to knuckle 

at this point.  I believe this geometry is a deliberate choice by the 
manufacturer and that there is some logic to it.  I don't think it's 
arbitrary or a result of lack of thought or understanding.  Whether or not 

this gives superior feel or control vs. the setup for minimum friction I 
can't say.  That's for pianists to decide.  Perhaps the choice wouldn't be 

universal.  Some pianists might prefer one setup and others another.

Phil F



Phillip Ford
Piano Service & Restoration
1777 Yosemite Ave - 215
San Francisco, CA  94124