Abstract: Detrimental buildup of tramp photoresist material upon the positioning pads of a stage plate for wafer printing machines is prevented by providing an arcuate point contact surface upon the positioning pads. The wafer is supported a predetermined focal length from the photoresist light curing source by said point contact support. The arcuate surfaces do not tend to collect deposits of adherent tramp photoresist material. The arcuate positioning surfaces are formed from a smooth, hard material. Preferably, the arcuate surface is provided by a hard ball bearing recessed into the surface of the pad and is adjusted during set up by a rod applied to the inside surface of the ball bearing which remains after adjustment of the arcuate surface to the proper position and serves as a reinforcement for the arcuate surface. The surfaces of the positioning pads are preferably mechanically cut back to accommodate the arcuate positioning surface in a retrofit installation.