Magnetic base drill

A drill unit for cutting holes in a metal workpiece, said drill unit having an electromagnet base with a generally flat bottom face for magnetically adherring the drill unit to a support surface on the metal workpiece when the electromagnet is energized, said drill unit having a pointed punch thereon adapted to be driven downwardly against and embedded into said workpiece support surface to resist lateral movement of the drill unit on the support surface, and means for driving said punch downwardly comprising impactor means including a vertically shiftable impactor operably connected with said punch to drive the punch downwardly in response to downward movement of the impactor, spring means acting on and biasing said impactor in a downward direction, a manually shiftable member on said drill unit engageable with said impactor means for raising the impactor and thereby increasing the bias of said spring means, and means for abruptly disengaging said manually shiftable member from said impactor means when the impactor is in a raised position to cause the impactor to move downwardly at a high velocity under the biasing force of said spring means and thereby impact the punch downwardly and against and embed it into the workpiece support surface.

In a drill unit for cutting holes in a metal workpiece, said drill unit being of the type having an electromagnet base provided with a generally flat bottom face for magnetically adherring the drill unit to a support surface on the workpiece and also having a vertically shiftable drill spindle spaced forwardly of the front end of said base, that improvement which comprises a bracket projecting rearwardly from the rear end of said base, a fixed stop projecting downwardly from the rear end portion of said bracket, said stop having a generally flat face at its lower end coplanar with the bottom face of said base, and a vertically disposed punch fixed on said bracket having an upper end and a pointed lower end, said pointed end extending downwardly below the lower end face of said stop, the upper end of said punch being free and unobstructed so as to be capable of being manually struck downwardly with a hammer.

In a drill unit for cutting holes in a metal workpiece, said drill unit being of the type having an electromagnet base provided with a generally flat bottom face for magnetically adherring the drill unit to a support surface on the workpiece and also having a vertically shiftable drill spindle spaced forwardly of the front end of said base, that improvement which comprises a bracket fixedly mounted on said drill unit and projecting laterally from said base, and a vertically disposed punch fixed on said bracket having an upper end and a pointed lower end, said pointed end extending downwardly below the plane of said bottom face, the upper end of said punch being free and unobstructed so as to be capable of being manually struck downwardly with a hammer while fixed on said bracket to drive the pointed end of the punch into the workpiece and thereby tilt the drill unit to a position wherein said bottom face of the base is in coplanar engagement with the support surface of the workpiece.

A drill unit for cutting holes in a metal workpiece, said drill unit having an electromagnet base with a generally flat bottom face for magnetically adherring the drill unit to a support surface on the metal workpiece when the electromagnet is energized, said drill unit having bracket means projecting laterally from said base and fixedly mounted thereon, a vertically disposed punch mounted on said bracket and having an upper end portion and a pointed lower end, said punch being slideable vertically on said bracket means from a position wherein the lower pointed end of the punch is disposed above the plane of said flat bottom face to a position wherein the pointed end of the punch is disposed below the plane of said flat bottom face, said upper end portion being adapted to be struck downwardly while mounted on said bracket to shift the punch downwardly on said bracket and thereby embed the pointed end of the punch into said work support surface to resist lateral movement of the drill unit on the support surface when the electromagnet is energized and means for retaining the punch in its downwardly driven position on said bracket embedded in said workpiece support surface.