One thing to know regarding Ball screws, is Ball Screws are not self locking (not the correct term). In other words, with a traditional ACME leadscrew putting pressure on the cross-slide or carriage will not case the screw to turn. Much like a worm gear driving a straight cut gear. The worm gear can cause the straight cut gear to turn, but not the opposite.
With Ball Screws, Force on the Ball nut can cause the screw to turn. Typical systems that use ballscrews have motors that apply a "holding" force that prevents rotation, even when the screw is not rotating.
So with Ball Screws, on a manual machine, one needs to lock the respective axis to keep it from moving when cutting.
