[ Spencer Chase wrote in 050920 MMD:

> Pure white Teflon is difficult to machine to the precise tolerances
> required of a piano action.

They probably would have made up an injection mold for the bushings.
They're quite accurate, and there are lots of mechanisms far more
accurate than piano actions -- though not wooden ones.

> However, the main problem, as I have heard, was that they did not
> consider the effect of a rigid bushing in a wooden part that expanded
> and contracted with moisture. ... This problem could probably have
> been solved by using a bushing with an elastic component that would
> allow the wood to expand and contract without altering the precise
> fit of the pin to bushing.

But we all know about the mixed durability record of rubber products
used in piano actions.  In that regard, I don't blame them for not
considering that particular alternative.

I am forever amazed at the cleverness of the materials and design of
piano actions.  Everything is cellulose-based: wood, felt, leather,
glue.  There are only a few metal parts: the odd nail or pull wire or
adjustment screw, and these are made of soft steel whose composition
and heat-treatment is not at all critical; they remind me of cuckoo
clock parts.

The wood is light and stiff, an ideal material still unmatched in
modern technology.  It is not dimensionally stable, but the action is
designed such that this won't be a problem; the flexible felt takes up
the slack.  The wood parts cannot be made to the accuracy needed for a
critical touch, so the action is designed with multiple linkages and
ballistic hammers to compensate.  Even the cheapest action is noiseless
and very fast.

From what I've read in Mr. Reblitz' work and other sources, the robust
and simple pinblock is the cause of many more ills than is the
delicate, complex action.

Mark Kinsler
Lancaster, Ohio, USA
http://www.mkinsler.com/