Jun 12, 2018 · The armatures measure 5-1/2 inches long by 3 inches in diameter and are mounted on pillow block bearings. A cut-out wooden board is bolted to each end of the hopper to contain the grain. “To make the rollers, I removed the commutator bar and winding coil from each armature, keeping the shaft. Then I used a cut-off wheel with a die grinder to