Motion-control systems that move fast or over long distances often lack repeatability. To overcome this, engineers at Bayside Motion Group ( in Port Washington, N.Y., use preloaded ball screws in their Luge LM Positioning Stages which maintain repeatability at 5 microns. A brushless servomotor built directly into the ball screw acts as a direct drive. This decreases overall length and provides better dynamic performance compared to conventional mounting methods. Eliminating the motor mounting and coupling also increases positioning accuracy and consistency, making the drive more reliable. Rotary encoder mounted to the ball screw eliminates build-up errors.