teflon

[Don Mannino]

Richard West wrote:

>>What is the general opinion about teflon?  Is everyone out there
replacing teflon parts with every opportunity to do so? (Iam.)
Is there any redeeming value to keeping teflon?  (I don't think
so.)  I'm curious if there's anyone out there still defending teflon.<<

Don Mannino's reply:

There _are_ benefits to the teflon bushing, but obviously the drawbacks
outweight the benefits or it wouldn't have been withdrawn from production. The
advantages are the combination of low friction with extremely tight control of
the action part's motion. The centers can be fit with close to zero measureable
friction, yet have essentially no play and little flex. This arrangement is the
ultimate for power transfer and minimum energy loss, although setting the
friction that low (especially with massive hammers) presents problems in
regulation. My experience with Teflon bushed concert grands is that they are
often exceptionally powerful instruments, and somewhat finicky to regulate at
times.

Fortunately, piano history has shown  that similar results can be obtained with
excellent, thin, firm bushing cloth, properly fit with a large center pin. Some
form of lubrication (I hate that word! For newer techs, I am NOT referring to
oil!) helps as well.   Teflon impregnation, graphite, or silicone are all used
by various manufacturers to achieve the firm but low friction fit, while
maintaining the resiliency of the wool bushing.

The drawback of Teflon for action center bushings is that it is unnacceptably
service intensive for many situations. The teflon is not sufficiently resilient
to take the forces presented to it during use, so it "bruises" and changes
shape, resulting in clicking, loss of control  and inneficiency.  We technicians
somehow prefer actions that don't need new bushings installed every few years,
as do the piano owners. Actually, maybe we technicians should reconsider - as
long as we're being paid, why complain???? ;-)

If I may plagiarize a bit: Takes a lickin' and soon starts clickin'

Don Mannino RPT
74473.624