[eugenebrooks]

We use a pair of springs made of surgical tubing to cancel the
force on an arm that tilts at the base of the robot by means of a
screw. Because sin(x) is approximately x for small angles, we
get quite good force cancellation and the tilt motor runs at free
speed.

We also use surgical tubing to help lift the heavier section of
a telescopting tube setup, but in this case we tune the spring to
cancel the force at a spot we think we will likely spend a lot of time
at. We would need a constant force spring, lifting 16 pounds,
to do better than that.

Worm gear life is a problem, we have to do everything we can
to extend gear life.