US Patent 7343685 Thread verification and chasing apparatus and method

A thread checking apparatus and method for threaded bores in small plastic parts, in which a threaded tap is mounted to rotate on a fixed axis at a workstation, the workstation having guide structure associated with the rotating tap to slidingly engage and guide a part with a threaded bore onto a free outer end of the rotating tap. The rotating tap draws the part down the length of the tap in sliding, rotation-preventing engagement with the guide structure, until the part's threaded bore is fully verified and chased, at which point the part engages a reversing limit switch to automatically reverse the rotation of the tap and drive the chased and verified part back off the tap.