A bearing block assembly for a plant-trimming machine having a rotatable perforated tumbler, a rotatable reel and a bed bar assembly. The bearing block assembly comprises an outer bearing plate having a bearing-receiving bore for holding a reel bearing to rotatably support an end of the reel, and an inner bearing plate affixed to the outer bearing plate. The inner bearing plate has a pocket for receiving the bearing-receiving bore of the outer bearing plate, the pocket having a tolerance permitting the bearing-receiving bore to be set at a selected position within the pocket. The bearing block assembly has connectors for affixing the outer bearing plate to the inner bearing plate. The bearing block assembly sets the positions of the reel, bed knife and tumbler correctly during assembly of the plant-trimming machine, reducing the time and skill required for maintenance.