"Tim Wescott" wrote in message
...

This is a pretty neat training gizmo for control loops. Sort of
like the
ball balancer, but better.

I considered doing a ball balancer, but I figured this would cost
less.

For that matter, I really wanted to do an inverted pendulum -- but I
couldn't see how to do the mechanism cheaply.

The wheel collars stayed tight on the flight home, yet the pot was
still
punched off the board. Not by as far -- but all leads broken is
still
all leads broken. I suspect that any sort of collar that rides
close to
the board to limit travel in that direction will either rub or have
too
much play to be safe -- but I could be wrong.

At this point what I see is a choice between some rotational slop
between
shaft and pot (which messes up the educational value of the thing),
the
current setup (which leaves it fragile, but possibly manageably so),
some
sort of a flex coupling or spring (assuming I can figure out how to
do
that well and cheaply), or some sort of a spring-loaded means of
holding
the shaft-pot joint to be snug in rotation, but still low friction
to
axial motion.

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com

http://www.dynapar.com/uploadedFiles...nting%20WP.pdf
#3, Direct mount with tether. The tether might be the connecting
wires.
jsw