Virtual Capstan

[Ron Nossaman]

>It is lessening the friction a lot probably, that may change under
>real play modes, while I don't understand how the magnet force act
>verse the inertial mass of the parts (what are the elements involved
>?)

I doubt any significant friction effect, though there may be. It's 
primarily just leverage. Using a random action model I have on hand for 
dimensions, 1g placed on the key where the magnet would be adds 0.79g to 
the touch weight. 1g on the wippen where the magnet would be adds 1.27g to 
the touch weight for a net +2.06g to the touch weight. 1g of magnetic lift 
adds 0.79g, and removes 1.27g, for a net loss of 0.48g to the touch. So 1g 
magnets must produce at least 2.06g lift to break even.

Setting this up, the lighter of the magnets should go on the wippen, and 
the adjustment and doubled magnets (if any) on the key because the weight 
penalty is greater on the wippen, where the lift wouldn't change.

>A couple magnets in the whippen rail and whippen lever should more
>work as assist springs (and with the same pitfall in regard of the
>help given only at the beginning of the stroke).

The boost isn't only at the beginning of the stroke, but it does lessen as 
the key goes down and the magnet gap widens.


>I bet that only once installed in a real action one can evaluate what
>it really gives, but if it help to break the initial inertia that is
>yet great, as this is what pianist tend to complain the most.

Yes, it will require a real fully working prototype or two.


>The effort is given in the same direction of the whippen lever spring
>also, so is the lesser friction at the heel  meaning more friction at
>the roller/lever interface, or does it stay the same under the same
>global force applied ?

Don't know.


>I wonder if a magnet is not exactly acting in the most optimum way
>against inertia lessening it far better than a spring because of its
>permanence.

It won't lessen inertia. It will increase it. The question is how it feels 
in play.