Abstract: A rotary workpiece treating apparatus is described particularly useful for depositing coating or adhesive materials within threaded fastener nuts. The device includes a continuously rotating turntable assembly having a plurality of workstation cylinders attached thereto. Installed within the cylinders are plungers having cam followers, which plungers move between a first and second position as the turntable assembly is rotated. A probe attached to the plunger is caused to enter within the internal bore of the nuts and release flowable material within the nut. The flow of such material is controlled by a valve stem protruding from the probe which is depressed against a stop surface when the probe is inserted within the nuts. A second clamping plunger within the cylinder clamps against the nut when the probe is being inserted, thereby positioning the nut and preventing flowable material from being deposited on the exterior surfaces of the nuts.