Abstract: A method and apparatus for imprinting high quality images on non-planar surfaces, including the surfaces of various types of three-dimensional articles, such as baseball bats, formed from a number of different types of materials. In the preferred method of the invention, the non-planar surfaces of the three-dimensional articles are printed using a uniquely modified ink jet image transfer technique. The apparatus of the invention includes a modified ink jet plotter coupled with a novel article positioning apparatus which functions to automatically maintain the surface of the article to be printed within a plan substantially parallel to and slightly spaced apart from the place within which the ink jet nozzles of the ink jet plotter reside.

Abstract: The invention relates to a method of producing concave, self-contained bearing surfaces, which are at least part of spherical indentations which extend beyond the sphere equator, by means of machining involving the removal of material of pre-formed indentations in workpieces by means of a tool having a tool cutting edge orbiting around a tool axis of rotation with an orbit diameter which is equal to the length of a chord extending up to a deepest point of the bearing surface, whereby the cutting movement is made up of the orbital movement of the tool cutting edge and a rotational relative movement between workpiece and tool around a vertical axis through the sphere center, and the feed movement is a movement of the tool relative to the workpiece along the tool axis of rotation which is obliquely set at the same angle of inclination relative to the vertical axis as is the chord set to the sphere equator.

Abstract: Apparatus for and method of automatically applying a lubricant to a gravure cylinder set in an gravure engraving machine. With a rotational drive mechanism of the gravure engraving machine biased to cause the gravure cylinder to be under rotation, a lubricant is discharged to and spread on the surface of the gravure cylinder. The lubricant application apparatus is moved axially of the gravure cylinder. Accordingly, the surface of the gravure cylinder is scanned such that the lubricant is applied onto the whole surface of the gravure cylinder. To move the lubricant application apparatus, an engraving head moving mechanism of the gravure engraving machine can be utilized.

Abstract: A method of producing an annular nonuniform groove (106) in the bore wall (104) of a casing (100) and a casing produced thereby is disclosed. The method includes the steps of forming a first portion (164), forming a second portion (172), and forming a third portion of an annular nonuniform groove. The first portion is formed by a first milling tool (168). The first portion defines a starting point (108) as the radial furthest point on the radially outer surface of the first portion. The first portion also defines a first intermediate point (166) as the radially closest point on the radial outer surface of the first portion. The second portion (172) is formed by a second milling tool (174, 180). The second portion is defined along the annular radial outer side wall from the first intermediate point to a second intermediate point (178). The second intermediate point (178) is defined as the radial closest point on the annular radially outer side wall of the second portion.

Abstract: A machine for carving workpieces having substantially similar configurations generally including a base member, means disposed on the base member for retaining at least one workpiece thereon, means for rotationally indexing the workpiece disposed on the retaining means, about an axis, a working tool operatively engageable with a workpiece disposed between the retaining means, supported on the base member and displaceable along x, y and z axes pursuant to a programmed sequence of motions coordinated with the workpiece indexing means for shaping the workpiece in a selected configuration, and at least one means for successively positioning a plurality of similarly configured workpieces in a selected orientation including a support member, a jointed linkage supported on the base member, supporting the support member and manipulatable to position the support member into a support relationship with an initial one of the workpieces disposed in the selected orientation and held by the retaining means, means for fixin

Abstract: A data encoding system for encoding input color pixel data and outputting encoded data. The data encoding system includes a reference pixel generating device which outputs reference pixel data corresponding to the input color pixel data to be encoded; a predictor having a color order table which sets the color ranks of color codes for every reference pixel pattern, reads and outputs the color rank of the corresponding color code from the color order table on the basis of the color pixel data to be encoded and its reference pixel data; and an entropy encoding device which converts the color ranking data into encoded data and outputs the encoded data.

Abstract: A tool carrier of a five-axis machine tool can be swivelled about a swivel axis which intersects a machining axis, about which a milling head is rotatable, in the region of the latter, at an acute angle which is preferably between 30.degree. and 60.degree., most preferably 45.degree.. As a result, during swivelling movements, only slight compensating movements, distributed over all the axes, are necessary, and yet the tool carrier can be kept short, so that deformations of the same remain small, which ensures high stability and great accuracy. In addition, large swivel angles of 90.degree. or more on both sides are possible without collision problems, which permits a great degree of adaptation of the position of the cutting edge to the workpiece surface and high surface quality as a result. The machine tool is especially suitable for milling turbine and engine blades as well as compressor impellers.

Abstract: The invention relates to a feed device for machine tools with chuck arranged at the free end of a spindle, to which chuck the workpiece is fed axially through the inside of the spindle from the rear by means of compressed air from a compressed air nozzle through the spindle (1) into the chuck (2), having a tool station arranged in front of the head of the chuck and having a stop which comes in front of the head of the chuck (2) in synchronism with the machining for halting the movement of the individual workpiece (8). In order to increase the productivity, a brake member is arranged in the axial hollow (11) of the spindle (1) between the entrance end and the chuck (2).

Abstract: A machine tool more particularly for drilling and milling, possesses a machine bed, on which a power driven longitudinal slide is adapted to run horizontally on rails. A machining head having a rotary drive device for at least one table forming part of said head, is power moved on the longitudinal slide in at least one further direction movement. The machine bed possesses two spaced lateral walls, on which the longitudinal slide is at least partly guided and whose intermediate space is designed in the form of a machining zone. On each of the two lateral walls a fastening point is provided for at least one pivoting work holding device, the two fastening points being aligned in a horizontal line, which defines a pivot axis, athwart the longitudinal direction of the guide rails. In such an arrangement the work holding means is readily accessible and is easy to service and furthermore may be simply replaced.

Abstract: Wheels of rail vehicles are trued while the wheels are kept rotating about a wheel center of rotation that is continuously corrected to keep the center of rotation in a fixed position in response to eccentricities a wheel may have, especially in its outer circumference. For this purpose, a sensor for each wheel of two wheels forming a set senses a respective excursion of a center of rotation of each wheel being trued in a set to provide respective excursion signals which are supplied to a central processing unit that provides control signals to a power drive for wheel guide rollers which support the wheel set to be trued. The power drive applies wheel position adjusting force components, preferably directed radially relative to the respective wheel rotational axis in response to the control signals from the central processing unit whereby the excursions are compensated and the wheel rotation center is kept in a fixed position.

Abstract: In a plural-roll rolling mill having a pass line arranged by the respective sets of rolls, each having a caliber formed on the outside peripheral surface thereof, the outside peripheral surfaces being disposed close to each other, the calibers of the rolls being cut with a cutting tool of a three-dimensionally (forward and rearward, rightward and leftward and upward and downward) movable cutting machine. The rolling mill, which has a reference column disposed on the outside surface thereof at a position spaced apart from the pass line by a predetermined distance, is removed from a rolling line and fixed, and the positional alignment of the cutting tool is carried out by causing a contact sensor disposed on the cutting machine at a position spaced apart from the cutting tool by a predetermined distance to come into contact with the reference column. With this arrangement, there are provided a method and apparatus capable of cutting the rolls of the plural-roll rolling mill while mounted on the rolling mill.

Abstract: A hobbing accessory is disclosed for a vertical milling machine of a type comprising a column, a knee mounted to the column so as to be vertically positionable with respect to the column, a saddle mounted to the knee so as to be horizontally positionable with respect to the knee, toward and away from the column, a table mounted to the saddle so as to be horizontally positionable with respect to the saddle, in opposite directions across the column, a head projecting from the column, an arbor mounted operatively to the head and rotatable about a generally vertical axis, and a motor for rotating the arbor about the generally vertical axis.

Abstract: An uninterruptive power supply is connected to an engraving apparatus. When power failure occurs, with supply of electric power from a back-up power source which is disposed within the uninterruptive power supply, a blank line detection part detects a closest blank line yet to be engraved, based on detection of the power failure by a power failure detection part. An engraving machine controller then ensures continued engraving up to the closest blank line and stops engraving. Following this, engraving is resumed after power supply is recovered.

Abstract: Apparatus and method for operating a numerical control router in which two processing tables are employed such that when a process board on one table is being processed, another process board may be loaded on to the second table and when processing is complete the first and second tables exchange positions.

Abstract: A router accessory having a housing with a router attaching portion for adjustable attachment to a router. The router accessory also comprises a plate for fixedly holding a work piece. The work piece support plate has a plurality of arms extending therefrom. There is also a plurality of track mechanisms attached to the housing. The arms are slidably attached to tile track mechanisms so that the plate with attached work piece can be guided in a desired path relative to the router bit. The track mechanisms can be constructed to guide the plate in only the x and y directions or in a preferred embodiment tile track mechanisms can have a varying height in the z direction for actively varying the spacing between the router and the work piece as the plate is slidably guided by the track mechanisms during routing. In this manner, cuts can be made in the work piece which have a contoured depth.

Abstract: A chamfer machine for providing a chamfer surface at the end of a workpiece. The machine includes a base and a guide member supported from the base for receiving the workpiece and disposed to enable the workpiece to move under gravity control. A rotary cutter is provided supported from the base with the cutter having a cutting surface adapted to engage the workpiece to provide a chamfering cut thereto as the workpiece is fed toward the cutting surface under substantially only gravity control.

Abstract: A device for making patches, especially of wood, and for patching resin galls on pieces of wood, comprising a rotatably drivable milling tool, which is rotatably driveable by means of a first driving unit and is held on a supporting frame. Also disposed on the supporting frame is a clamping device, which is rotatable about a rotational axis. A remnant of the workpiece to be patched can be clamped in this clamping device and, by means of rotation about the rotational axis, can be led past the milling tool during which the lateral surface of the remnant is milled. Afterwards the clamping device can be lifted, the remnant being again led past the milling tool, the lateral surface being milled. Afterwards the patch made in this way can be detached.

Abstract: In a wheelset processing operation, in which non-positive driving of the wheelset (1,1') is effected, the processing tools (2,2') act on the wheelset (1,1') at the same time in different directions such that the tangential components (3,3') of the tool forces are substantially compensated. This enables the wheelset processing time to be reduced and enables the machining accuracy to be improved.

Abstract: A system performing a conical transition from a shaft to the core diameter of a worm is disclosed. The disclosed system includes inserting a rough milling machine in an axial direction before a disk milling machine used for milling the worm. The rough milling machine is especially manufactured integrally with the disk milling machine. The teeth of the rough milling machine are shorter than the teeth on the disk milling machine, and the teeth of the rough milling machine preferably define a truncated-cone shaped covering.

Abstract: A method of processing a leading portion of a rotating workpiece is performed by rotating a tip mounted on a cutter shaft and facing an outer circumferential surface of the workpiece. The tip has a small radius of rotation for high precision processing with small cutting resistance. The leading portion is cut by the tip with the cutter shaft inclined to a side opposite to the leading portion of the workpiece with respect to a direction orthogonal to the axis of rotation of the workpiece.

Abstract: A repair apparatus 78 for repairing the combustion chamber assembly 32 of a gas turbine engine 20 is disclosed. Various construction details are developed which increase the speed of the repair process and the structural integrity of the repaired combustion chamber assembly. In one particular embodiment, the repair =apparatus has a support assembly 82 which is adapted by locating pins 98 to engage the lug mountings 48 of the combustion chamber assembly 32.

Abstract: Apparatus for turning and milling a workpiece includes a frame having a chuck and a spindle spaced laterally of the chuck mounting respective opposite ends of the workplace for rotation generally about its longitudinal axis. A carriage mounting the milling device is supported by a rail on the frame for movement generally side-to-side of the frame and longitudinally of the workpiece. A first variable speed electric motor operatively connected to the chuck for driving the rotation of the workpiece about its longitudinal axis is controlled by a first control, which is used to selectively set the rotational speed of the workpiece.

Abstract: The invention relates to a method for producing a cylindrical body comprising at least one stud having a cylindrical base portion projecting from its rotating surface in which a cylindrical body blank is produced comprising a peripheral collar of external diameter equal to that of the stud or studs to be obtained, and of width greater than the diameter of the base of the stud or studs to be obtained.

Abstract: A router accessory used in concert with a router attached to a router table. The accessory can be used to produce rosettes, model wheels, buttons, coasters, and other circular decorated projects, for example. In the preferred embodiment, a wooden workpiece can be positioned horizontally above a selected router bit. The workpiece zero point, which may be the workpiece center, can be off-set horizontally from the router bit. The accessory can then be used to lower the workpiece onto the router bit, so that rotation of the workpiece routs a circular cut equidistant from the workpiece zero point. The maximum depth of cut can be set. The off-set can be changed to make additional circular cuts into the workpiece, as desired.

Abstract: A method for machining a workpiece. The method includes the use of a rotary cutting tool mounted on the end of a movable arm. The arm is adapted to move in a plane perpendicular to the axis of rotation of the cutting tool. The cutting tool has cutting teeth to cut chips of material off of the workpiece in a predetermined size and shape to facilitate better removal of the chips from the workpiece. The teeth can be of different type and length to permit the tool to both rough cut and finish cut the workpiece during machining. The total depth of cut is divided by the number of tool teeth, so that the longest tool always performs the finishing cut.

Abstract: An under-the-floor lathe for re-machining the wheels in railroad-vehicle wheel sets. It has two assemblies for each wheel in the set. Each assembly comprises an upright, a swiveling head, an axle-bearing support, a hold-down, two friction rollers that can be positioned against one of the wheels, and a friction-roller holder. At least one of the friction rollers in each holder is powered. Each holder rotates around an axis that travels along the mid-plane of the lathe. The object is to accelerate the machining action without using brakes that engage the friction-roller holders. Two pressure-application devices that generate opposite torques in relation to their associated pivoting axis are attached to each friction-roller holder.

Abstract: The production of differential speed reduction apparatus, which uses a double-toothed gear including face cams having tooth profiles uniquely generated to secure efficient speed reduction. The speed reduction apparatus includes an input shaft carrying the double-toothed gear, a slant shaft wobbling in association with the rotation of the input shaft, a stationary face gear engageable with the face cams, a movable face gear secured to an output shaft, wherein the stationary face gear and the movable face gear have a roller-like or a convex-face contour.

Abstract: The spindle of a machine-tool is mounted on a carriage movable along a horizontal transverse member which is carried by the columns of a part of the frame of the machine having the shape of a closed porch, and which is situated in front of these columns. This transverse member moves vertically along the columns. The workpiece-carrying table, which can rotate on itself, is mounted on a carriage movable in a direction parallel to the spindle axis on a portion of the frame situated in front of the porch. Thus, the machine is compact and, whatever the extreme positions of its movable elements might be, no cantilever condition is produced which could generate machine deformations.

Abstract: Apparatus for monitoring or tracking the angular position of a rotating camshaft during grinding or milling of cams on the camshaft. The cams may be milled, but in the apparatus shown, they are ground by abrasive belts which are guided by actuators driven by CNC controlled motors, to obtain the desired cam contours. Monitoring is carried out by a pick-up member engageable with a locating pin on the camshaft. The pick-up member has a slot for receiving the locating pin between a locator pad and a leaf spring. The leaf spring clamps the pin against the locator pad. The pick-up member will closely follow the rotation of the camshaft despite variations in pin size, and feed back the exact rotative position of the camshaft to the CNC controlled motors consistently and accurately.

Abstract: A fly-cutter milling machine for the simultaneous milling of a plurality of profiled structures developed in the form of grooves, surfaces or the like in rotating workpieces by means of a fly cutter which protrudes radially outward on a rotating tool holder and which plunges through the cross section of the workpiece with a speed corresponding to the conditions of the fly-cutting, the speeds of rotation of tool holder and workpiece being in a ratio determined by the desired profiled structure, and in order to increase the range of use of the fly-cutter milling machine, the speed of rotation of the fly cutter over the emerged path differs from that over the plunge path.

Abstract: A fly-cutter milling machine for the simultaneous milling of a plurality of grooves (12) in rotating workpieces (2) by means of a fly cutter (3) which protrudes radially outwards on a rotating tool holder, the speed of revolution of the tool holder and the speed of revolution of the workpiece being in a ratio which is determined by the number of grooves of the workpiece. In order to obtain optimum operation with the groove profile precisely adapted to the tool cutting edge, the rotation of the workpiece (2) is briefly interrupted at the moment of the maximum depth of plunge of the fly cutter (3) by a phase of reduced speed of the workpiece (2).

Abstract: A method and apparatus for cutting a pair of circular grooves in the side edges of the periphery of a circular disk such, for example, as the stator of an alternator. A milling cutter having axially spaced cutting elements along its periphery is positioned so that its axis is parallel to the axis of the disk. The cutter is moved toward the disk while being axially rotated, to cause the cutting elements to cut into the side edges of the periphery of the disk. The disk is then rotated one full turn to cause the cutting elements to cut the grooves.

Abstract: Router jig apparatus includes a base portion, a router positioning portion, a workpiece orbiting portion and a workpiece positioning portion. The base portion includes a quadrangular frame section disposed generally horizontally and a supporting stand extending downwardly from the frame section. The router positioning portion includes a plate section slidably engageable with the frame section, the plate section includes a central first opening of a shape to pass a motor of an inverted router and retain a work surface surrounding a bit thereof. The workpiece orbiting portion includes a guide section disposed above and closely adjacent to the frame section, the guide section including a large circular second opening therein. A disc member is rotatably positioned within the guide section opening, generally in a common plane therewith, the disc member including a central third opening.

Abstract: An apparatus for retracting the tool from a machined piece on a machine comprising a movable assembly for holding the tool or the piece having a guide means for taking up play by lateral biasing.This apparatus involves means intended for providing lateral displacement of the said movable assembly away from its position for taking up play so as to separate the tool from the piece after machining.For a machine tool with an indexible rotating tool-holding spindle, the tool is indexed in a plane approximately parallel to that of the means for taking up play prior to activation of the above mentioned means which is utilized to separate the tool from the piece.

Abstract: A machine for tapering the ends of lengths of fiberglass pipe is disclosed. The machine includes an enclosing cabinet having mounted therein an electric motor and a vacuum system. A grinding wheel is rotated by the motor within the cabinet and preferably the vacuum system is wired for operation at all times when the electric motor is operated. One or more stationary mandrels mount in spaced relationship to the grinding wheel and are slightly angularly oriented relative thereto. Portions of the mandrel extend exteriorly of the cabinet to provide a positioning projection to receive one end of a length of fiberglass pipe in sliding engagement. The pipe is manually fed over the mandrel toward the rotating grinding wheel and is rotated as it is inwardly urged to form a circumferencial taper in the end of the fiberglass pipe.

Abstract: A clamping ring for use in pipe joints has an inside surface which is formed with generally peripherally extending indentations for axially fixing a pipe. In order to prevent an occurrence of dangerous stress concentrations in pipes in contact with such clamping rings and to permit such rings to be manufactured economically, the clamping ring is formed on its inside surface with a multiplicity of generally peripherally extending indentations, each of which extends only along part of the periphery of said inside surface, and said indentations are offset from each other in said peripheral directions and adjoint or overlap.

Abstract: A fine grinding machine for crankshafts, camshafts and the like, has a fixed headstock housing in which the spindle carrying the workpiece chuck is rotatable and axially reciprocatable. The chucking action is effected by an axial displacement of the spindle by a setting mechanism which acts upon the spindle via the same member as that which transmits the axial reciprocation thereto for the oscillating drive. A flexible connection in the rotating drive permits the axial movement.

Abstract: This invention relates to metal cutting and more particularly to method for manufacturing constant velocity universal joints. A construction is disclosed wherein spherical turning, milling and grinding of the races and grooves of the joint members of a universal joint are performed on common machines without removing the workpieces and the workpieces are held in common workheads. During the machining operations, relative movements between the tools and workpieces are referenced to common axes thereby duplicating the relative positions and movements between the workpieces during actual service. The inventive concept provides a means for achieving consistent product quality and is adaptable to the automated manufacturing of constant velocity universal joints.

Abstract: The present invention relates to a method and apparatus for reprofiling the wheels of a railroad wheelset by circumferentially milling the wheelset while the wheels are driven and partly supported by drive rollers, the wheelset being partly supported at its bearing housing. Before profile milling, a reference surface is created by a turning operation as base for measuring the radial infeed of the profile milling cutter. The turning tool required is disposed on the profile milling cutter which is lockable secure against rotation. By coordinating the position of the milling devices with the position of the respective turning devices a positional relation is automatically established between the milling device and the axis of the wheelset.

Abstract: The present invention is a work piece holding device for use with a work table having a power tool positioned adjacent a work station on the work table. The holding device comprises a pedestal, an elongated arm having first and second opposite ends, a universal hinge connecting the first end of the arm to the pedestal for pivotal movement about both a horizontal and a vertical axis, and a handle on the second end of the arm. A work piece holding device is rotatably mounted to the arm intermediate the opposite ends thereof, and is adapted to rotate about a vertical axis. A crank handle is connected to the work piece holding device for causing the rotation of the holding device about its vertical rotational axis with respect to the arm.

Abstract: The machine comprises a support surface for a reference surface on the body of the workpiece, and a device for fixing the body on the support surface and releasing the body. A withdrawable device is provided for angularly positioning the blank on the support surface. The device comprises a V-shaped recess facing the support surface. The machine permits a center-less grinding of cylindrical surfaces in overhanging relation and in particular trunnions of tripods for homokinetic joints.

Abstract: A non-circumferentially relieved surface is ground on the spiral cutting edges of an axially elongate tool using a grinding attachment mounted on a tool supporting table for linear movement to the peripheral edge of a grinding wheel having a fixed finger adjacent the revolving grinding wheel edge adapted to engage behind the portion of the cutting edge being ground to guide the rotary and axial travel of the tool relative to the grinding edge. The tool is supported on a centerless support on the attachment and a top roll is pressed down on the tool shank. The attachment and tool are moved manually forwardly on the table in a grinding pass at a speed dictated by the "feel" of the operator, and while moving the attachment and tool axially and manually revolving said roller at a speed dictated by the "feel" of the operator in timed relation to the forward movement of the attachment and tool.

Abstract: A machining center for machining the interior of an elongate tubular workpiece includes a bed on which a rotatably indexable member is slidably mounted for movement on the bed along a first axis. Removably fastened on the indexable member in spaced parallelism are a first and second hollow bore spindles each engaging the exterior surface of a tubular workpiece whose interior is to be machined. The first spindle is rotatably driven to rotate the tubular workpiece about its axis responsive to machine tool control system commands slidably mounted on the bed for movement thereon along a path perpendicular to the path of member movement in an upright. Extending from the upright parallel to the axis of upright movement for insertion into the workpiece bore is an arm which is movable along the upright along a vertical direction. At the distal end of the arm is a right angle, high speed rotary driven cutting tool carrying spindle.

Abstract: A true centering steady rest for rotatably supporting an elongated cylindrical workpiece for a metal working operation on the outer diameter of the workpiece, such as a grinding operation. The steady rest includes a housing in which is slidably mounted a pusher arm carrying a workpiece center wear pad. A pair of side arms are slidably mounted on said pusher arm. Each side arm carries a replaceable wear pad engageable with a workpiece at a point in the range from 90.degree.-140.degree. from the center wear pad. The center and side wear pads are moved into operative engagement with a workpiece when the pusher arm is moved toward the workpiece, and they are disengaged from the workpiece when the pusher arm is moved away from the workpiece.

Abstract: An apparatus and method for making a belt construction having a plurality of alternating annular belt projections and grooves along its axial length are provided wherein the apparatus comprises an open ended building drum for building a tubular uncured structure, a curing device for curing the structure to define a belt sleeve, a cooling device for cooling the sleeve with the sleeve disposed around the drum, and a device for supporting and rotating the drum and sleeve to enable cutting thereof with a rotatable cutter wherein the supporting and rotating device comprises a plurality of rotatable support shafts including a driving shaft, with the shafts being adapted to be disposed within the hollow open ended drum and into pressure engagement against the inside surface thereof to support such drum, a drive for rotating the driving shaft with the shafts in pressure engagement against the inside surface to provide rotation of the drum and sleeve, and a cutter control apparatus for controlling the cutter during ro

Abstract: In a process of milling a multiple-throw crankshaft comprising mainshaft portions and crankpins in alternation, two outer crankpins of three axially consecutive crankpins are milled at the same time while the crankshaft is supported at its ends and at the mainshaft portions which connect said three crankpins.

Abstract: A machine for simultaneously milling several grooves in rotating workpieces by means of a rotating one-toothed milling tool, whereby the rotational speeds of the milling tool and workpiece stand in a ratio determined by the number of grooves, and whereby the milling tool in the longitudinal direction from the free end of the workpiece--freely-cutting--is plunged in the workpiece which is advanced in the longitudinal movement. The tool carrier is pivotable about an axis lying perpendicularly to the rotational axis of the workpiece such that the rotational plane of the cutter tool is able to be brought in an acute angle relative to the rotational axis of the workpiece.

Abstract: A flat, elongate workpiece such as a knitting-machine needle, stamped from sheet metal with a transverse lug whose narrow faces require precise machining, is clamped in a workpiece holder with its lug centered on an axis about which the workpiece holder and an associated tool mounting are relatively rotatable. The tool mounting includes two symmetrically positioned supports, carrying respective power-driven shaping tools such as grinding wheels or millers, which are limitedly movable in a plane including the axis and are interconnected by a tension spring drawing them toward each other. An interposed cam disk, engaged by rollers mounted on these supports, determines the extent to which the two shaping tools can approach the axis in machining respective lug faces during a relative rotation of up to 180.degree..