The pneumatic lift version of the Lapmaster Model 36 is based on the Open Face design, but the pressure weights are attached, through selfaligning bearings, to the rods of three pneumatic cylinders. These are mounted vertically on sliding rails within a fabricated hollow assembly, known as a “spider bar”. This fabrication is cantilevered over the lap plate and is mounted onto a tubular upright column bolted to the machine frame. The free end is restrained by a tie rod to prevent excessive bending stress when high lapping pressures are used.