Abstract: An improved boring bar for machining bearings in an engine block or the like includes a plurality of circumferentially spaced wear pads which extend radially beyond the surface of the bar and form the sole points of support between the bar and the inner race of a bearing in which the bar is slideably received. Preferably, at least two of the wear pads are radially displaceable within slots on oposite circumferential sides of longitudinally aligned cutting tools which are secured to the bar. The pads are removably mounted in the slots within the bar by screws to allow rapid replacement of the pads due to wear. A thin layer of resilient material, such as neoprene rubber, is captured between the radially displaceable pads and the bottom of the slot, and urge the pads away from the bar, thereby biasing the bar in a direction away from the cutting tools and toward one side of the inner race of the bearing. The constant lateral biasing of the bar eliminates tool chatter and improves machining accuracy.

Abstract: A device adapted for use with electrical discharge machining apparatus generates tapped holes in a workpiece using a threaded, hollow carbon tool. The tool is releasably connected to a reversible hydraulic motor by a coupling which feeds dielectric fluid through the interior of the tool into the space between the machining tip of the tool and the workpiece. The motor is mounted on a vertically reciprocable slide arrangement carried by a support which is mounted on the head of the conventional electrical discharge machine. The tool extends downwardly through a threaded guide which is held in spaced relationship to the workpiece by the support, thereby allowing fluid emanating from the tip of the tool to carry machined fragments upwardly out of the tapped hole. The slide includes a slide plate mounted on a pair of upright guide posts carried by the support.

Abstract: A device adapted for use with electrical discharge machining apparatus generates tapped holes in a workpiece using a threaded, hollow carbon tool. The tool is releasably connected to a reversible hydraulic motor by a coupling which feeds dielectric fluid through the interior of the tool into the space between the machining tip of the tool and the workpiece. The motor is mounted on a vertically reciprocable slide arrangement carried by a support which is mounted on the head of the conventional electrical discharge machine. The tool extends downwardly through a threaded guide which is held in spaced relationship to the workpiece by the support, thereby allowing fluid emanating from the tip of the tool to carry machined fragments upwardly out of the tapped hole. The slide includes a slide plate mounted on a pair of upright guide posts carried by the support.