I need to make a pair of very low friction pivots for a measurement
system. I don't need much range of motion, say +/- 20 degrees. It's the
sort of application where a knife edge would work. I've seen reference
to using carbide for knife edge bearings, and was thinking about using
carbide lathe inserts for the "knives". However, that still leaves me
with what sort of material to groove for the knives to rest in. This
supposed to be a "quick and dirty" job, and I'd prefer to avoid having to
heat treat the grooved parts.
I'm basically building a pendulum system for measuring the moment of
inertia of some irregularly shaped objects. The items to be measured
will be suspended just below a pair of pivots, and set swinging. By
knowing the mass and location of the center of gravity, I can estimate
the moment of inertia by measuring the period of the resulting pendulum.
Any drag will damp the swing and screw up my readings. I've thought
about just hanging them by a string, but that seems a bit too crude.
Anyone know what sort of string has the lowest flexing losses?
Any suggestions for the knife edges, or some other sort of low friction
pivot? The things I'm testing weigh several pounds, so the forces on the
pivots aren't tiny, but they aren't enormous either.
15 years ago