All North Star slab rollers have two rolls, much like the wringer of an old-fashioned washing machine. Both rolls have a small diamond pattern ("knurling") machined directly into the metal to grip the canvas. The bottom roll is turned by the handle, but cannot move vertically. As it turns, it drives the top roll through a train of gears. The upper roll both turns and can be adjusted up and down. The two rolls turning together pull slabs through easily, and the vertical adjustment of the top roll gives an easy-to-set and infinitely adjustable thickness from paper-thin to over 2 inches. A reference scale allows setting and repeating openings to within 1/100 of an inch.
The design gives great flexibility in making slabs. Very thin, translucent porcelain slabs and thick, heavily textured architectural slabs are equally easy. A wide variety of other texturing materials and objects can be passed through the machine along with the clay. Slabs can be rolled either direction or reversed on all North Star machines.