Action Geometry

[Paul S. Larudee]

Richard Brekne wrote:

> It seems to me that Stanwoods approach is what I will call a  "weight
> priority" approach. That is to say that certain component weighting factors
> can take precedence over geometrical concerns.

You hit it on the nose, Richard.  I took David's all day class at the PTG
convention in July, and while I'm very glad I did, that is exactly what
occurred to me.  At the same convention, however, I ran across an action
weighting system which absolutely blew me away.  It uses adjustable paired
magnets and permits action charactersitics that ought to be impossible.

It is called the Magnetic Balanced Action and is the brainchild of Evert Snel
and Hans Velo (Netherlands).  It is available through Fazioli and was mounted
in a Fazioli at the convention.  Although what drew the most attention at the
convention was the capability to change the touchweight of the instrument
uniformly in about 30 seconds with a few adjustments from the front of the
action, a more significant feature, in my opinion is that it completely
eliminates the need for key leads, and therefore vastly improves the inertial
characteristics.  It also makes the hammer weight independent of the key
weight, which allows you to select or even design hammers according to other
criteria.

Prefer more inertia?  No problem.  Just add weights on both sides of the
balance hole or put them in the front and reduce the strength of the magnets by
turning the regulating screws to which they are mounted.  Once the system is
installed, the entire action can be touch regulated to perfect uniformity
without any disassembly.

No, I don't sell the system.  Wish I did.  This doesn't directly address the
issue of weight vs. geometry (I consider distance part of geometry), but it
allows geometry, weight and inertia considerations to be addressed
independently, with relatively little regard for their interaction.

Paul S. Larudee, RPT
Richmond, CA