[CAUT] fulcrum of a key

[Keith Roberts]

>
>        Another question, and one I was trying to get at, was having to do
> with the ability to analyze an action geometrically. When I have tried to
> measure all the lever arms (key, wipp, and shank) and do the fairly simple
> multiplication and division, I have come up with a ratio that is a good bit
> different from what I get with measurement of dip versus hammer rise, or of
> variation by weight (adding a known weight to the hammer and measuring how
> much heavier BW is at the front of the key). So I'm thinking that some point
> in back of the balance hole should probably be used when calculating the key
> ratio for this purpose. Maybe it should be as far as the edge of the
> punching.
>
>
> Regards,
> Fred Sturm
> University of New Mexico
> fssturm at unm.edu
>
You have three moving points, all of which are changing as the action goes
through its cycle. Only at the crossing of the magic line is the force
directed entirely along the axis of the jack or capstan. Total distance
moved is less than theoritical because of the scrub caused by the two arcs.
Action ratios change differently with different parts or alignment of parts.


By measuring hammer rise using a mm by mm depression of the key and graphing
the key ratio in rise vs dip can you see the changes of ratio.
Keith
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