Abstract: Molding apparatus including a thermally transmissive mold liner and a packing nub having a spring biased positioning pin for uniformly forming and molding grinding wheels. A locating pin at a bottom mold plate secures the liner to the bottom plate and indexes a threaded arbor and the nub to the pin. The positioning pin positions the nub to the arbor. Upon leveling a charge of a mixture of resin adhesive and abrasive material, a top plate is concentrically fitted to the nub and liner. The pressing of the top plate and nub with the bottom of the nub aligning with the bottom of the positioning pin provides uniform compaction. The liner supports the molded green wheel during curing and after which the wheel is removed.