Abstract: A tool support for a hand tool machine includes a housing surrounding a drive spindle having a recess to receive a tool-receiving sleeve. This recess accommodates a compression spring which biases an end portion of the sleeve. The sleeve is also provided with a tool-facing portion receiving a tool to be used and an intermediate shaped portion which is arranged for a possible slidable movement within an adapter rigidly mounted to the drive spindle. A second sleeve is provided in the tool support which is threadably mounted on the tool-facing portion of the tool-receiving sleeve and is arranged so that its axial position may be adjusted. Said end portion of the sleeve has such a length that the length of contact of this end portion with the recess should be relatively larger than the combined length of contact of the shaped portion of the tool-receiving sleeve with the inner surface of the adapter and a possible path of the second sleeve in the axial direction.

Abstract: An apparatus for centering and indexing of milling machine parts, in particular angle milling heads on a spindle carriage of a milling machine. Cooperating indexing elements are arranged on the angle milling head and on the spindle carriage, which elements are simultaneously also the centering elements. These are constructed as four similarly constructed aligning units which are arranged offset to one another each at 90.degree. in peripheral direction. Each aligning unit consists of an aligning tab arranged on the one milling machine part, preferably the angle milling head and a fixing piece provided on the other milling machine part and has a groove therein. The angle milling head can be fixed in predetermined angular positions relative to the spindle carriage through the aligning units.

Abstract: A needle-roller type chuck for machine tools which includes a chuck body having a chuck barrel integral with the leading end portion of the chuck body. The chuck barrel has a leading end portion and an outer peripheral surface tapered to form a conical surface, and includes a plurality of holes extending from the leading end of the chuck barrel toward the chuck body. A rotatable clamping ring is positioned over the chuck barrel and has an inner conical surface extending in the axial direction of the chuck and parallel with the outer periperal surface of the chuck barrel. A needle-roller assembly having a plurality of needle rollers is positioned between the chuck barrel and the clamping ring in rotatable contact with the conical surface of the chuck barrel and the clamping ring.

Abstract: The chuck assembly and the collet for retaining an end mill tool against axial pullout. The collet includes a radially compressible body having a tapered outer surface, a central bore and a radial aperture extending from the outer surface into the central bore. The radial aperture has an undercut or larger diameter medial portion with a movable pin mounted therein, said pin being movably mounted and, adapted to extend into the bore to retain the tool. The pin has a hole drilled through with a spring bar mounted therein. The ends of the spring bar are compressed to a length smaller than the diameter of the radial aperture and inserted into the larger undercut portions where the expansion of the spring bar retains the pin. The hole in the pin is larger than the diameter of the spring bar to allow the pin to move along its axis (radially into the collet bar).

Abstract: In a draw-bar mechanism for moving the collet of a chuck or the like on a spindle of an automatic turning machine toward its axial clamping position and for thereafter closing the collet more slowly with greater force about a tool or workpiece to be clamped, motion is transmitted from an actuating sleeve to a draw bar or like control member by spherical thrust members movably confined between three faces obliquely inclined relative to each other. A first face is fixed relative to the spindle assembly and has one section parallel to the axis and another axially contiguous section obliquely inclined relative to the axis, the two sections merging in an exposed edge. A second face is fixed relative to the control member, and the third face is fixed relative to the actuating sleeve and has two axially consecutive sections obliquely inclined relative to each other.

Abstract: A cutting tool assembly having a cutter head including a pair of jaws defining a slot therebetween with a knife plate having a pair of axially symmetrical cutting edges being exchangeably mounted in the cutter head in the slot between the jaws is provided with a setscrew adjustably connecting the knife plate on the cutter head and with a pair of support members arranged at the base of the slot between the knife plate and the cutter head cooperating with the setscrew to enable adjustment of the knife plate. The support members are internally threaded and interconnected by a bolt having oppositely threaded portions with oblique abutment surfaces being formed on the support members for engagement with the knife plate.

Abstract: An improved tool for removing burrs formed on the edge of drilled holes is provided and comprises a first and second elongated arm member. Each arm member includes arcuate cutting lobes formed on one axial end. The other axial end of each arm member is received within a collet so that the arm members are spaced from but substantially parallel to each other and with the cutting lobes positioned on the outer periphery of each arm member. The collet includes appropriate locking means whereby each arm member can be individually attached to and detached from the collet, and, preferably, the collet is adapted for attachment to the outwardly extending end of a tool holding rod of a tool holder.

Abstract: A toolholder assembly incorporated in a portable power tool having a housing and a drive disposed therein. The assembly includes a toolholder body, a first releasable securing arrangement for attaching the toolholder body to the drive for oscillating the toolholder body in a longitudinal direction; a second releasable securing arrangement at the front end of the toolholder body for attaching a tool bit to the toolholder body, longitudinal guide faces provided on the toolholder body between the two releasable securing arrangements and a bearing member mounted in the housing and provided with longitudinal counterguide faces which slidably cooperate with the longitudinal guide faces of the toolholder body for taking up forces transverse to the direction of the longitudinal oscillation of the toolholder body.

Abstract: There is disclosed a tool retaining mechanism employing a nose piece including an axially extending, longitudinal bore which accepts the tool bit. The nose piece includes a first opening which is disposed so as to cut through a portion of the bore. Slideably disposed in the opening is a retaining pin which includes a first cutout which cooperates with the profile of the bore and the tool bit, in a first position, to allow insertion or removal of the bit. Means are described for urging the pin axially in its opening to a position where it cooperates with the contour of the bit to retain the latter in the tool once inserted.

Abstract: A mechanical system for allowing removable attachment of tools to a robot which is capable of accommodating positional and angular errors between the tool and the robot during attachment and release of the tool by using tapered attachments.

Abstract: Tool-fitting device characterized in that a clamp socket is fixed at the bottom of a hole bored in the spindle; a tool-fitting body with a clamp piece at one end is placed over the clamp socket; and through the connection of the clamp socket and the clamp piece, the rotation of the body caused by the cutting torque is restrained, the cutting thrust is borne, and pull-out is prevented; and through connection of a rotation-restraining engaged members which is restrained in rotation relative to the spindle and the rotation-restraining engaging member which is restricted in rotation relative to tool-fitting body, rotation of the tool-fitting body in a pull-out direction is restrained.

Abstract: An adjustable tool holder for securing a drill or like tool to the turret of a machine tool includes an axially extending body member, a tool receiving member positioned alongside the body member, and a radially contractible clamping member encircling both the body and tool receiving members. When the clamping member is contracted, the contours of its circular interior cooperate with the contours of the body and tool receiving members to result in an axial positioning of the members.

Abstract: A torquer/thruster with a hydrostatically actuated chuck assembly having an elastomeric bladder that is fitted about a cylindrical collet into which a flexible roof drill is received. The collet is formed with a series of spaced slits that are disposed in helical paths, portions of the collet between the slits drivingly engage the drill shaft when the bladder is urged against the collet. The collet and bladder are mounted for rotational movement within a piston assembly that is constrained for limited longitudinal movement and fixed against rotational movement. The collet and bladder are moved longitudinally by the piston assembly for applying thrust to the roof drill and are rotatably driven by a rotary driver for applying torque to the roof drill. A pair of driven biased members engage the shaft and provide thrust assistance and retraction of the roof drill.

Abstract: A tool holder has a socket to receive the shank of a tool, a transverse bore breaking into the socket, and a tool retaining device for insertion in the transverse bore comprising a rigid retaining pin bonded to a resilient member which urges the retaining member sideways so that part of the retaining pin projects into the socket to engage the shank of a tool inserted therein. An elongate element is bonded to the resilient element and includes, at opposite ends thereof, stop members which overlie surfaces of the tool holder surrounding the ends of the bore, and thereby prevent longitudinal movement of the retaining device in the transverse bore. The stop members may be moved, by deformation of the resilient member, to a release position where they lie within the cross-section of the transverse bore, so that the retaining device may be inserted into, or withdrawn from, the bore.

Abstract: A combined boring and milling tool has at least three triangularly shaped turnable cutter blades. The effective cutting edge of the first turnable cutter blade extends as bit (or drilling cutting edge) from the periphery of the shank at least to its axis. A second turnable cutter blade is offset 180.degree. peripherally from the first and its effective cutting edge extends as cutting edge on the periphery of the shank parallel to the shank axis. A third turnable cutter blade is offset axially from the first so that its effective cutting edge extends as a cutting edge parallel to the shank axis. The two effective cutting edges of the second and third turnable cutter blades lie on the same flight circle and their working ranges overlap axially. The first and third turnable cutter blades have a common chip space.

Abstract: A holder for a rotary metal cutter for use with a milling machine having a shouldered head portion, a cutter and a clamp member. The cutter is sandwiched between the clamp member and the shoulder of the head portion. Where it is desired that the cutter be adjustable on a horizontal plane, a variation of the holder is provided, which includes a clamp element cooperating with a clamp member to permit the required rotation and to assure a secure clamp on the cutter after adjustment. Variations of the holder are included for engaging two cutters set on opposite sides of the holder.

Abstract: Tool for drilling holes, such as cylinder head drill, woodworking drill, and the like, which includes a carrier member having at least one endwise arranged end face cutter, or first cutting means, and at least one precutter, or second cutting means, extending in endwise direction, and circumferentially beyond the carrier member, the precutter defining the diameter of the hole to be produced with the tool and including at least one cutting edge. At least the part adjacent the cutting edge of the precutter is approximately parallel to the pertaining circumferential portion of the carrier member. The outer side of the precutter includes at least one guide surface parallel to the outer circumferential portion of the carrier member. The end face cutter and the precutter are removably securable with at least one clamping element to the carrier member and can be in the form of reversible cutting elements.

Abstract: An indexable insert drill having a cylindrical body with two flutes and a cutting insert mounted at the end of each flute. The cutting inserts are mounted so that each presents a cutting edge of a length less than the radius of the drill with each edge being positioned to provide negative lead and effectively neutral radial and axial rake. The first of the cutting edges intersects the longitudinal axis of the drill body and extends radially outward to an end area spaced inwardly from the circumference of the drill body. The second of the cutting edges extends from an outer end area radially outward of the drill body circumference to an inner end area radially inward of the radial outermost end of the first cutting edge. Preferably, the first cutting edge extends over two thirds of the radial dimension of the body and has an effective cutting length of at least twice that of the second cutting edge.

Abstract: A tightening and clamping mechanism for the mandrel collar of a milling or boring spindle. The clamping elements are semi-circular devices with notches in their outer surfaces. By engaging the notches with retainer pins and tightening actuators, the clamping elements may be closed around the mandrel collar thereby securing it to the spindle housing.

Abstract: An adjustable boring tool including an axial shank and a socket for mounting a cylindrical boring bar with an offset axis clamped in adjustable position through transverse and longitudinally slotted segments on one side of the socket together with a transverse screw for clamping the slotted segments against the boring bar. A graduated dial fixed to the boring bar provides calibrated adjustment over a range equal to four times the offset.

Abstract: An indexable insert drill with a parallelogram shaped insert positioned at a negative axial lead, the insert having a slanted recess which provides an angularly oriented cutting edge extending from a face cutting corner through or slightly under and substantially beyond the drill axis, and a unique notch in the cutting edge providing chip interruption and stabilized lead.

Abstract: A clamp for a tool spindle for rapid interchange of tools without the need to raise the spindle or lower the work further than the end of the tool to allow clearance. The clamp is provided with a recess co-axial with spindle and the tool is provided with an adapter extension movable into the recess in a direction normal to the axis of the spindle or recess. A clamping gate hinged at one side of the recess is then locked to the other side of the recess to complete the recess and lock the tool adapter in position. A locking screw on the gate is then rotated into engagement with a flat on the adapter to integrate the clamping unit and tool. Means are also provided for axial positioning of the tool.

Abstract: A ball endmill comprises a cylindrical body and a cutting element secured to one end of the cylindrical body. The face of the cutting element is convexed and forms a part of the surface of an imaginary cone, the axis of which is inclined to the axis of the cylindrical body. The cutting element is constituted by one or more parts and has at least one arcuate cutting edge. The cutting edge has its starting point located near the axis of the cylindrical edge and cuts in a workpiece a spherical concave as the cylindrical body is rotated.To cut a deep hole with a spherically curved bottom, the ball endmill may be provided with an auxiliary cutting element. The auxiliary cutting element is secured to the periphery of the cylindrical body and has a straight cutting edge extending parallel to the axis of the cylindrical body. The straight cutting edge cuts a straight cylindrical hole in a workpiece as the cylindrical body is rotated.

Abstract: A machine tool arrangement comprising a main electric motor including a rotor having a hollow cylindrical rotor shaft intergral therewith and extending therethrough. A hollow driving spindle is disposed coaxially with the rotor shaft and the spindle is inserted in the rotor shaft at one end thereof for relative axial and rotation movement. The spindle is driven in rotation by the rotor and it is provided at its opposite end with an arbor-receiving opening. A draw rod extends through the rotor shaft and the spindle and has an externally threaded end engageable in the internally threaded opening in the arbor for securely attaching the arbor to the spindle. A positioning mechanism serves for adjusting the position of the arbor relative to a workpiece.

Abstract: The disclosure relates to a combination of a tool holder having a socket member with a cylindrical axial bore, and a tool shaft releasably received therein. A driving element is displaceably mounted in the socket member so as to be movable between an extended position in which part of the driving member extends into the axial bore, and a retracted position in which the driving member is retracted from the bore, and the driving element is biased towards its extended position by spring means. The tool shaft received in the tool holder has a transversely extending recess receiving the driving element in its extended position, whereby the tool shaft is locked in the tool holder. Adjacent to the free end of the tool shaft the said recess defines an abutment surface cooperating with an inner surface part of the driving element in its extended position so as to prevent axial withdrawal of the tool shaft from the axial bore of the socket member.

Abstract: A clamping device, especially for clamping tools in a turret or the like, in which each tool is provided with radially outwardly movable clamp elements and an actuating element carried by the tool movable axially for actuating the clamp elements. The turret in which the tool is mounted includes mechanism for driving the actuating element in actuating direction and for releasing the actuating element from actuating position to release the respective tool from the supporting turret.

Abstract: A combination tap and die wrench is provided having a center portion with an aperture extending through the thickness thereof for receiving and retaining tapping apparatus and at least two oppositely extending arm portions extending outwardly from the center portion, each of said arm portions including a plurality of receptacles for receiving and retaining dies. An extension handle is also provided and may be secured to either of the arm portions at their outwardly extending ends. Storage means for tapping apparatus may be provided in the handle.

Abstract: An improved cutting tool includes a tool holder having a recess in which an insert is held by a retaining screw. The retaining screw has a head end portion which extends into an open recess formed in a side of the insert to press the insert against bottom and side surfaces of the tool holder recess. To maximize the length of a threaded opening engaged by the retaining screw, the screw has a central axis which extends at an acute angle to a central axis of the tool holder. The bottom and side surfaces of the tool holder recess extend at acute angles to the central axis of the tool holder to firmly support the insert during a cutting operation. An outer end portion of a shank of the tool holder has a generally oval cross-sectional configuration which provides clearance for chips cut from a workpiece and also provides a relatively strong support for the insert.

Abstract: A reamer having a tool shank and a detachable reamer head in which the shank is provided at one end with means to be engaged by the spindle of a machine tool and at the other with a sleeve defining a conical socket and the reamer head has an integral conical butt for engagement in the shank socket, the butt being detachably secured in the socket by means of a rigid force transmitting member extending lengthwise of the tool shank and connected at its ends to the reamer head butt and an axially movable screw threaded counterpiece engaged in screw threaded fashion on the shank so that rotation of the screw threaded counterpiece exerts a longitudinal force to draw the reamer head butt into and out of the conical head socket. Cooperating detent means are provided on the reamer head butt and tool shank sleeve to prevent relative rotation therebetween.

Abstract: A combination tap and die wrench is provided having a center portion and a pair of opposite arm portions extending outwardly from the center portion. The wrench is preferably fabricated from a material with a high strength per weight ratio such as aluminum. The center portion which is circular with a pair of opposed flat surfaces includes a central aperture extending through the thickness thereof from one of the opposed surfaces to the opposite surface. The central aperture is adapted to receive and positively retain tapping apparatus. At least one round, depressed receptacle is provided on each of the surfaces of the center portion about the central aperture for receiving and positively retaining a threading die.

Abstract: Holder for a threading die. A die holder is provided for threading elongated items of circular cross section, particularly pipe or rod, which can utilize dies of either hexagonal or circular external contour, which can be arranged to reach otherwise awkward places, which can be rotated either by a wrench or by handles and which under certain conditions of use permits a long article such as rod material to pass entirely therethrough. A generally tubular body part has a recess, preferably hexagonal, in one end thereof for the reception of either a hexagonal or a circular die. If a circular die is used, same can be held in position by a set screw. The other end of said body member is externally contoured for receiving a wrench and has an end opening of normally rectangular cross section which is on a common center with the axis of said die. Thus, said die holder can be rotated by a wrench either directly on said last-named end thereof or through an extension inserted into said rectangular opening.

Abstract: A cordless electric drill has a housing formed by two clam-shell sections secured together by a plurality of fasteners. These housing sections define a closed motor and gear compartment which receives a sub-assembly, the latter including a generally U-shaped gear box frame mounting a small D.C. electric motor, a plurality of reduction gears and a spindle. A drill chuck is mounted on the spindle. The sub-assembly and the housing sections include co-operating mounting formations, defined in part by projections and cavities, which mounting formations serve to mount the sub-assembly in place in response to securing the clam-shell housing sections together by the aforesaid fasteners.

Abstract: A machine tool having a tool-supporting hollow spindle has the tool mounted in fixed relation to a draw bar which slides axially within the spindle between a tool retaining position and a tool release position. A barrel cam within the spindle is adapted to be engaged and rotated by a cam driver member secured to an actuating shaft longitudinally movable within the spindle. The spindle rotates with the cam until a predetermined angular position is reached, after which additional longitudinal movement of the actuating shaft causes movement of the draw bar downwardly within the spindle from its tool retaining position to its tool release position, where the tool is resiliently supported until it is removed, either manually or by automatic means.

Abstract: Cutting tool assemblies each of which includes a cutting head attached to the end of a shank holder and a drill adjustably mounted to be moved longitudinally of the shank holder and projecting through the cutting head. In one form the cutting head is a chamfering tool which produces a countersink in the top of the hole in a workpiece bored by the drill. In another form the cutting head is a spot-facing tool which produces an annular flat surface around the hole bored in the workpiece by the drill. The cutting head is fixed to the shank holder and is driven thereby. The drill is clamped to the cutting head so that it is driven with the cutting head by the shank holder. Adjusting means is provided to move the drill axially in the shank holder so that the cutting head completes its cutting operation when a hole of the proper depth is drilled, or shortly thereafter.

Abstract: A single flute drill having a single, replaceable cutting insert which can drill from the solid, as well as being used for other single point machining operatings such as turning, internal and external diameter boring, contouring and facing. The insert is configured and related to the drill body so as to provide a single, radially extending cutting edge which has an effective neutral rake and negative lead. A specific insert structure is also provided for use in the drill. The disclosed insert comprises a solid body having parallel upper and lower faces each generally in the shape of an equilateral parallelogram and joined along their peripheral edges by side walls. One cutting edge is formed along the juncture of one side wall and the upper face and is inclined along its length toward the lower face. A second cutting edge is formed along the juncture of the lower face and a second side wall which intersects the first side wall at a corner.

Abstract: The invention deals with a quick-change-device for a conical, hollow bore spindle of a machine tool in particular a milling machine, for the quick releasing and clamping of tools or tool holders that have conical shanks and which have a ring groove on the end which is facing away from the tool, into which radially movable projections of a clamping element engage, and which projections are part of a longitudinally shiftable drawbar in a spindle, which under the effect of clamping springs act on the drawbar, the clamping element engaging and pulling the conical shaft of the tool holder into the spindle cone of the machine tool; and the clamping element is detachable due to compressing the clamping springs through a power means.

Abstract: An indexable insert for cutting internal and external grooves in a workpiece is adapted for mounting and securing upon a tool holder having a pocket therein; whose bottom edges define an obtuse angle. The insert comprises an elongated body of rectangular cross section having a flat top surface along one edge of the body and a pair of angular bottom surfaces extending from a central point of the body and inclined toward and extending to said top surface at a corresponding included obtuse angle. These inclined surfaces define a pair of separately usable transverse cutting edges at the opposite ends of said body which is adapted for snug registry within said pocket. Said pocket also defines within the tool holder a back up plate against which the insert bears. The insert, one or more, is held down within said pocket by a clamp which bears across the top edges of said inserts. A cam lock device is also mounted upon said holder to apply lateral pressure to the insert holding it snugly against the back up wall.

Abstract: A cutting or drilling spindle and a tool unit supportable within the spindle for rotation with the spindle wherein the tool unit is provided with radially extending protrusions which can be received within corresponding inner radially spaced recesses within the spindle. The radial protrusions of the tool unit comprise balls support adjacent the exterior surface of the axial neck of the tool unit by a cage and which operate in such a way that during axial insertion of the tool unit into the spindle and locking, the radially outwardly extending portions of the balls will be engaged in the spindle's recesses. The balls are relatively movable such that if they are not properly aligned with the recesses when the tool unit is inserted into the spindle, the balls facilitate correction so that the protrusions of the tool unit will match the indentations of the spindle.

Abstract: A cutting tool holder includes an elongated holder body having a first end face through which passes a shaft receiving bore which extends longitudinally through the holder body to receive an elongated tool mounting shaft therein. The tool mounting shaft has an end collar at one end and is threaded at its opposite end to be releasably fastened to the holder body with the shaft extending through the holder body, and the tool mounting portion of the shaft protruding therefrom. A plurality of substantially disc-shaped shaft mounted members, including cutting tools and spacers, have opposite faces and are received in face-to-face relationship on the tool mounting portion of the shaft, between the end collar and the holder body end face. The end collar and each shaft-mounted member is provided with locator means comprising complementary-shaped recesses (holes or grooves) and protrusions (pins or bars) formed, respectively, on the adjacent faces thereof.

Abstract: There is disclosed a spindle unit for machine tools in which there is a spring operated drawbar in the spindle having finger hooks for engaging the adapter of a toolholder for drawing the latter into a tapered socket at the nose of the spindle with means for locking the finger hooks in engagement with the toolholder adapter and automatically operated means for relieving the pressure of the hooks against the toolholder adapter and providing push rod means to cause the finger hooks to move clear of the adapter and apply a force to the toolholder so that the latter, with the tool carried thereby, may be removed from the spindle socket. The spindle is advanced toward the work and retracted therefrom by a tubular quill provided with a helical groove to cooperate with a ball-nut means formed integrally with a pulley which is connected by a timing belt driven by a pulley on the shaft of a stepper motor, the advancement of the spindle depending on the number of step-like movements of the motor.

Abstract: A counterbalance mechanism for a vertically movable machine tool headstock in which the net counterbalance force applied to the headstock is the same for both upward and downward movement of the headstock so that the accuracy of the spindle alignment is not disturbed by such movement. The counterbalance mechanism includes a hydraulic control system which automatically provides a greater pressure to a hydraulic counterbalance cylinder during raising movement of the headstock than during lowering movement so that difference in forces exerted by the counterbalance cylinder as a result of said pressure differential compensates for frictional resistive forces in the counterbalance mechanism and thereby enables the same net counterbalance force to be applied to the headstock.

Abstract: A rotary spindle of a drill mount has a free end provided with a thread whose angle of rise is so selected that its tangent is at least equal to the coefficient of static friction of steel on steel.

Abstract: The invention is concerned with an improvement in a machine tool gripping assembly of the type which comprises a housing with a bore therewithin and a collet slidable toward and retractable from a spindle facing end portion of said bore, the collet having extending from a spindle facing end thereof a plurality of resilient leaves each attached at one end to said collet and separated at a spindle gripping end thereof, each of said leaves having a first annular cam surface adjacent said spindle gripping end thereof, said surface being formed at a selected angle with respect to the longitudinal axis of said collet.

Abstract: A combination extension and compression tool holder having a cylindrical outer housing adapted to be inserted into a chuck of a rotary drive machine. A tool holding rod is axially slidably mounted in a cylindrical recess formed in the housing for rotation about its axis of elongation. Two opposing helical springs are disposed within the cylindrical recess and bias the tool holding rod towards an intermediate position within the cylindrical recess. During the feed-in of the machine chuck during a deburring operation, one of the helical springs can be compressed to permit the deburring tool to be retracted when the deburring tool engages an unfinished hole resulting from drill breakage to thereby prevent the deburring tool from being forced into the unfinished hole and thereby broken. During the deburring operation of a normally formed hole, the compression spring will permit the deburring tool to dwell at the opening of the hole for a better deburring operation.

Abstract: A compression tool holder for use with deburring tools or the like, the tool holder having a cylindrical outer housing adapted to be inserted into a chuck of a rotary drive machine. A tool holding rod is axially slidably mounted in a cylindrical recess formed in the tool holder. A spring loaded piston is mounted behind the rod and urges the rod to its extended position. A cap member, however, defines the limit of the extended position for the rod. The rod has an outside diameter somewhat smaller than the inside diameter of the cylindrical recess in the tool holder so that the rod may compensate for misalignment by pivoting relative to the housing within the cylindrical bore, utilizing the cap member as the fulcrum point for its pivot. The end surface of the piston coacts with the end surface of the tool holding rod so as to return the tool holding rod to a central aligned position when misalignment compensation is not required.

Abstract: A spade drill characterized in that the slotted blade clamping end of the holder has non-symmetrical oppositely disposed blade clamping faces, each of which extends close to the cutting end and cutting diameter of the blade on the side of the blade opposite to the side containing one cutting edge thus to provide firm support for said one cutting edge and is beveled at its end to provide a wide divergent passage for free passage of chips from the other cutting edge to the longitudinal obtuse angle groove of the holder which intersects such divergent passage at its wide end.