To meet this demand, engineers at Schneeberger Inc., Bedford, Mass. (www.schneeberger.com), have developed NDN-Series stainless-steel slides. Overall height can be as low as 4 mm, strokes range from 5 to 70 mm, and load capacities go from 5 to 85 lb.

The slides consist of equal-length saddle and base sections, ball bearings, and a unitized brass ball cage. The U-shaped cage surrounds the base and serves two purposes. It retains and properly spaces the two rows of balls between the saddle and base. Balls are preloaded between the saddle and base. The cage also works with the retaining screws as a recentering mechanism. In place of end stops or screws mounted on the ends of the rails to prevent cages from migrating beyond the rail, NDN slides use two small screws to retain the cage. The one installed from the outside protrudes slightly past the saddle and base into a rectangular slot in the brass cage. The slide can move back and forth, but the screws eventually hit the end of the internal slot, thus resetting the cage.