Machine Design

Spaced-Out Ball Screws

Elastic spacers that separate recirculating balls inside ball-screw nuts improve fine and slow motion.

Conditions such as frequency oscillations or intermittent short strokes often cause balls in regular ball nuts to touch, resulting in interball friction and idling torque, which could potentially cause instability in servoloop control. The durable-plastic spacers resemble two Belleville springs back to back. Slight compression of each spacer between two adjacent balls ensures sustained close guidance during recirculation. A hole in the middle of the spacer lets adjacent balls touch each other (through the spacer hole) in the event of a jam. The spacers are suitable for use in precision machine tools, including grinders and electrodischarge machines (EDMs).

Steinmeyer Inc.,
11 DeAngelo Dr., Bedford, MA 01730,
(781) 275-6097,

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