A drill tool comprises a drive shaft (2) that is arranged to allow rotational movement to be transmitted from a drill to a drill bit holder (10) even when the opposite ends of the drive shaft are not axially aligned. The end of the drive shaft housing the drill bit holder (10) can be inserted into a guide member (14) that includes a planar element (18, 42) that is arranged to ensure that the drill bit is maintained at substantially 90.degree. to the surface of a work piece being drilled even if ...

A twist drill including a cutting tip having a front flank face, a substantially cylindrical tool body extending rearwardly from the cutting tip, and a shank. The tool body includes a rotational axis therethrough and at least one flute formed on an outer peripheral surface thereof and extending to the front flank face. The at least one flute includes a first helical portion opening to the front flank face and a second helical portion extending from the rear end of the first helical portion towar...

A drill bit for drilling a well bore using solid material impactors comprising a nozzle and a cavity for accelerating the velocity of the solid material impactors and directing flow of the solid material impactors through the nozzle. The drill bit may also comprise a junk slot for return flow of the drilling fluid and solid material impactors.

A sonic drilling apparatus having a work piston within a cylinder chamber to provide a vibratory force through the alternate application of fluid under pressure into the bore above and below the piston in a manner that the piston will be forced to reciprocate within the bore. The cylinder chamber includes an inlet gallery to allow fluid under pressure to pass into the bore above a first face of the work piston and an exhaust gallery to allow fluid to escape from the bore below the second face of...

A tool for a power drill allows fast and convenient loading and unloading of a screw bit, drill bit, or other implement. The user preferably loads the tool with the necessary implements which are then carried with the tool. Each received implement is movable from a storage position to an in use position in drive engagement with the power drill or power screwdriver. The desired implements can rapidly be changed from one to the other, while the implements are retained on the tool.

A driver drill that can effectively prevent erroneous clutch operation in a drill mode is provided. A flat washer positioned between steel balls for locking an internal gear and a coil spring is rotatable by rotative operation of a mode-change ring. Also, protruding streaks are provided on a small-diameter unit of a second gear case around which a flat washer is externally mounted. The protruding streaks interfere with internal projections on an inner circumference of the flat washer at its pred...

A concrete drill for drilling concrete or the like by a diamond bit (5) attached to a front end of a bit drive shaft (4) projected forward from a main body (1) by driving to rotate the bit drive shaft (4) by a drive source (2) contained in the main body (1) in which the main body (1) is provided with a vibrating apparatus (8) for exerting a vibrating force a magnitude which is pulsated to change along the bit drive shaft (4) to the main body (1).

A drill bit has a pair of cutting teeth with cutting elements extending from a cutting end portion of the drill bit. Each cutting tooth extends radially, outwardly parallel to a longitudinal axis of the drill steel. The cutting teeth are juxtaposed with one another on the longitudinal axis. Each cutting tooth includes a plurality of raised cutting elements connected to a plurality of lowered edge portions. The cutting elements produce concentric circular channels in the working surface of a rock...

An impact drill includes a first ratchet together with a spindle and movable in an axial direction, and a second ratchet engageable with the first ratchet. The second ratchet can be moved in the axial direction, and rotated with a predetermined range in a rotational direction.

A drill chuck has a chuck body centered on and axis, and a tightening element surrounding the body and rotatable thereon about the axis. The tightening element has a front sleeve formed with jaw-holding guides and a rear sleeve releasably coupled with the front sleeve. A retaining ring bears axially forward on the sleeve. Releasable locking formations on the ring and body are relatively displaceable between a retaining position preventing axial rearward shifting of the ring and sleeve on the bod...