Fail safe stop for a drill press control device

摘要

Quality control attachment adapted to be fitted onto a threaded depth control bar of a drill press machine includes a sleeve having an axial opening for fitting onto the control bar and being longitudinally movable relative to the bar. The sleeve carries a pawl and an elastic O-ring which urges an edge portion of the pawl into engagement with the threads of the control bar for enabling one-way movement of the control bar downwardly through the sleeve. An actuator pin is slidably disposed in a bore which extends through the sleeve and is movable downwardly in response to contact with a stop-nut disposed on the bar when the drill press has advanced to a preset depth represented by the position of the stop-nut. The attachment serves to prevent retraction of the drill from a hole unless the control bar, which tracks axial movement of the drill, has moved downward sufficiently for the actuator pin to contact the stop-nut and shift the pawl outwardly of the control bar thereby ensuring that the hole has been drilled to its preset depth.