I was wondering what others thought about wheather or not to convert to a ballscrew on the knee of a Bridgeport. As far as I know, and I am very likely missing something, the big advantage to the ball screw is that you can get zero backlash and you can lock the axis with just locking the motor. Neither one of these advantages are really show stoppers on the knee. I assume that the reduced friction will allow the use of a smaller motor, but not by that much unless you also do a gas spring or counterweight. If you use a good sized spring or counterweight then the zero backlash becomes more important, but still not sure it is necessary. Easiest is just to use the acme screw and bigger motor.

Thoughts, opinions?