Abstract: An apparatus for use in renovating tube systems, in particular, sewer tubes of a circular cross section. The apparatus includes a frame on wheel, with the frame being arranged so as to be moved inside a tube in such a manner that a position of the apparatus in the tube is determined. A motor-driven tool is arranged for cutting away items extending or protruding into the tube and/or for forming side openings in the tube wall or in a tube lining. The motor driven tool is mounted on a carrier arm extending beyond an end part of a rotatable portion of the apparatus. The carrier arm is pivotally connected, opposite the tool, to the rotatable portion at a distance from the end part thereof. An inflatable lifting member is arranged inside the rotatable portion between the end part of the rotatable portion and the pivot axis of the carrier arm. The lifting member is interposed between the rotatable portion and the carrier arm in such a manner that the tool can be moved diametrically within the tube.

Abstract: Disclosed is an improved inner surface shaper comprising, on a bed, a first reciprocating stock having a first working spindle and a drive screw, a servomotor to drive the drive screw for making a linear reciprocation of the first reciprocating stock, a second reciprocating stock having a second working spindle, a hydraulic cylinder to drive the second reciprocating stock toward and apart from the first reciprocating stock, and a tool rest placed between the first working spindle and the second working spindle. The first working spindle, second working spindle, drive screw and hydraulic cylinder are arranged along the center line of the bed, and the hydraulic cylinder and first reciprocating stock are connected by two joint rods which are arranged symmetrically with respect to the center line of the bed.This arrangement has the effect of directing undesired counter force to the joint rods and the longitudinal axis of the drive screw.

Abstract: A method is disclosed for finishing a roughly shaped elliptical cylinder bore to an accurate final shape of predetermined major and minor axis. A circular cutter body with an effective diameter equal to the desired major axis. Then, a tilt angle is determined at which, when the circle of the cutter body is tipped away from the bore axis with the bore axis running through the center of the circle, a projection of the circle into a plane perpendicular to the bore axis will yield the desired minor axis. Then, the cutter body is powered about a secondary axis, at the tilt angle, relative to a bore primary axis and advanced linearly into the bore along the bore axis.

Abstract: There is provided by the present invention a surface contouring tool useful for reaching otherwise inaccessible working surfaces such as large diameter gas turbine engine rotor inner surfaces, the invention including a machining head means extendable from a nonworking position to a working position relative to the working surface and when the machining head means is useful for EDM or ECM machining further includes a fluid flow path for providing a machining fluid to the working surface head and means for rotating the machining head means.

Abstract: The present invention relates to a boring device adapted to bore the lining material blocking a branched portion where there is an opening for connecting a main pipeline with a branched pipeline (33), after the inner surface of a pipe (31), such as a gas conduit, a city water conduit or a sewerage pipe, in particular, a conduit buried in the ground, has been lined with lining material (30) for maintenance, repairs and reinforcement purposes.The features of the boring device reside in improvements of the mode of attachment of the television camera (8) for projecting the position of the leading end of the borer (28) on its screen, the mode of attachment of the borer (28) to the body (9), the driving system of the borer (28), and also of the cutting blades of the borer (28) for cutting off the lining material.

Abstract: A machine tool to machine a workpiece includes linear slide blocks supported one by the other on a pedestal to present a mounting surface for supporting a workpiece, a support head includes a rotary indexing table that in turn supports an elongated cutter bar the support head to define an outwardly projecting cantilever end portion that is in turn supported by an outboard support, a cutter tool is supported for rotary movement about an axis transverse to the extended length of the cutter bar, a drive means extends along the cutter bar for rotating a cutter tool. The drive to rotate the tool in one embodiment takes the form of a belt extending between pulleys one of which drives the tool and the other is coupled to the electric motor in the drive head. A hydraulic motor is mounted in the cutter bar to rotate a tool according to a second embodiment.

Abstract: Disclosed is an industrial endoscope system having a rotary treatment member, attached to a hard top part at a distal end of an insertion unit, for effecting a treatment such as grinding by rotating this treatment member itself. The system includes a moving means for making a distal end of the treatment member movable in the axial directions of the insertion unit. This easily leads the treatment member to a target position via a lead-in port of an engine; or the treatment member can be set in a position suitable for the treatment.

Abstract: Heretofore, dimples or recesses that were distributed over the periphery of a cylindrical wall of a counterbore in a component had to be formed or inserted one after the other, which required complicated positioning work. According to the invention, in order to simultaneously form all of the dimples with a simple positioning device, a deflection body is provided through which at least two milling spindles pass in a planet-like disposition relative to a central control rod. The deflection body is connected to a centering piece facing the counterbore and to an intermediate piece facing away from the counterbore. The intermediate piece in turn forms a type of cylinder/piston connection with a gear housing. Each milling spindle is connected to an output shaft of a gear housing by a flexible shaft that is axially movably guided in between.

Abstract: The device for making a drilled hole with an undercut consists of a drilling machine and connected rotatable drilling tool, a supporting stand for the drilling machine having a holding device with a bearing bush secured in it, and a sleeve fixedly joined to the drilling machine. The sleeve is rotatably mounted in the bearing bush. A lever (35) is attached to the drilling machine (12), a cam plate (39,49) having a circumferential surface (40,60) is attached to the supporting stand (3) and a crank are provided for the lever. An end of the lever (35) remote from the drilling machine (12) is connected with the crank so that the lever can be pivoted and the drilling machine with the drilling tool swung out.

Abstract: A system for cutting lateral holes in plastic pipe liners at the locations of lateral taps in a surrounding pipe comprises a cylindrical body which is inserted into the pipe liner, and remote devices for observing and controlling operation of the body. A rotary cutter, having axial and radial cutting teeth, can be remotely translated in three dimensions with respect to the body, making it possible to cut non-circular holes; the body can be rotated about its axis within the liner as well. A video camera on the sled permits observation of the cutter. Lateral taps are precisely located by monitoring return signals from a microwave transmitter/receiver on the sled, and identifying points of maximum deviation in microwave reflection.

Abstract: A method for making monobloc points for a transporation rail is disclosed. The points include a profiled body having a groove for housing a point rail. The method includes selecting a steel bloom having dimensions at least equal to the outer dimensions of the body and machining the steel bloom to define the profiled body.

Abstract: An apparatus is shown for cleaning a pipe. The apparatus includes a rigid stem and a motor stationarily mounted on the stem. An outer body surrounds the motor and is rotatably mounted on the rigid stem. A fluid conduit is connected to the stem and to a source of fluid under pressure for supplying fluid to the motor for driving the motor. The fluid conduit also connected to a pulling unit for pulling the apparatus through the pipe to be cleaned. Fluid supplied through the fluid conduit to the stem and through the stem to the fluid powered motor provides rotational propulsion to turn the outer body as the apparatus is moved through the pipe to be cleaned.

Abstract: A system for cutting lateral holes in plastic pipe liners at the locations of lateral taps in a surrounding pipe comprises a cylindrical body which is inserted into the pipe liner, and remote devices for observing and controlling operation of the body. A rotary cutter, having axial and radial cutting teeth, can be remotely translated in three dimensions with respect to the body, making it possible to cut non-circular holes; the body can be rotated about its axis within the liner as well. A video camera on the sled permits observation of the cutter. Lateral taps are precisely located by monitoring return signals from a microwave transmitter/receiver on the sled, and identifying points of maximum deviation in microwave reflection.

Abstract: An apparatus (1) for work inside piping comprising an elongate clamping and/or moving unit (2) with a working attachment (8) at one end. The unit (2) is provided with two arrays of radially projectable feet (6, 7), suitably at either end thereof. The working attachment (8) includes radially projectable elements (22), all of which are adapted for being displaced to the same extent, and one array of feet (6) placed at the end of the unit (2) opposite the working attachment being adapted such that its feet are thrust out to the same extent. The unit (2) suitably comprises two parts (4, 5) which are mutually, reciprocally movable, there being an array of feet (6, 7) arranged in each part (4, 5).

Abstract: The present invention relates to an inside processing apparatus for performing operations of cleaning, grinding, cutting and the like toward an inside of piping of a water pipe, a gas pipe, a wire pipe and the like. The said inside processing apparatus is constituted by possessing a working head having the working member (tool) for performing a fixed work on the cylindrical wall surface, a driving mechanism for moving the said working member in the circumferential direction of the cylindrical wall surface and a cutting controlling mechanism for controlling a quantity of the movement in company with a fact that the said working head is moved in the radial direction of cylindrical wall surface by the said driving mechanism.

Abstract: A method and an apparatus for conducting predetermined operations in the interior of a pipe with a cutter, in which the cutter is shifted so that a rotary axis of the cutter is angularly displaced about an axis extending along the pipe and is displaced in the axial direction of the pipe while the cutter is rotated about an axis extending in the axial direction of the pipe or about an axis extending in the radial direction of the pipe.

Abstract: A method of and an apparatus for removing any burrs or other undesired defects from a workpiece having a bore therein is disclosed. Specifically, those burrs or other defects that are to be removed may be present on the marginal edge or interior of the bore. The method and apparatus are specifically designed to allow a rotary tool to meet the specific relationship requirements between the number of revolutions (n) and number of reciprocating motions (N), i.e., 1/3.ltoreq.n/M.ltoreq.1, when the rotary tool travels forward and backward within its specific stroke range.

Abstract: The apparatus comprises a carriage (2) which carries on one face a working head (8) for a tool such as a milling tool (18). The working head is fully rotatable about the longitudinal axis of the carriage by means of a drive (10) acting on a gear (11) and is held in a bearing (9) and supported by a rotating shackle (12). The milling tool rests on a shaft (17); a mounting flange (19) makes it possible to use various types of tools, and in particular wheel-type tools. The shaft (17) is driven by a hydraulic motor (16). The working head (8) comprises a feed cylinder (13) wherein is located the hydraulic motor (16) just mentioned and the shaft (17) and which can be radially extended with regard to the pipeline (1). On the bearing (9) a holder (7) with a television camera is attached.

Abstract: An apparatus for boring a hole, which affords communication between a first member and a second member connected to the first member, in the first member, comprises cutting means hvaing a rotary axis, first drive means for shifting the cutting means along a first axis extending in the direction orghogonal to the rotary axis, second drive means for shifting the cutting means along a second axis orghogonal to the rotary axis and first axis, third drive means for rotating the cutting means about the rotary axis, detecting means for detecting a load acting on the cutting means and control means for controlling the first and second drive means to correct the position of the cutting means on the basis of a detecting signal provided from the detecting means so as to prevent an overload from acting on the cutting means.

Abstract: Method for the non-destructive removal of tubes or of portions of tubes from heat exchangers, comprising:(a) the lengthwise cutting along at least one generatrix of one tube or of a plurality of tubes of said exchanger, to a depth at least equal to the thickness of the tube plate and to a width of up to 2% of the outer perimeter of the tubes;(b) the approaching to each other of the edges of the so-obtained cut section up to the complete release of the tube, or of the tubes, from the tube plate;(c) the possible crossways cutting of the tube, or of the tubes, to a height at least equal to double the thickness of the tube plate; and(d) the recovery of the tube, or of the tubes, by sliding same out of the said plate.

Abstract: A tool for cutting a keyslot in a workpiece bore for use with a numerically-controlled (N.C.) machine of the type having a plurality of tools for performing a number of machining operations on a workpiece. The tool includes a spindle which is insertable in the driving mechanism of the N.C. machine and a shaft fixed to the spindle for driving a cutter wheel responsive to spindle rotation. The spindle is received in a housing which is automatically locked against rotation relative thereto when the tool is not in the driving mechanism of the N.C. machine. An adjustable ring permits changing the cutting plane of the cutter wheel to vary the angle at which the keyslot is cut in the workpiece bore.

Abstract: Apparatus for cleaning the inside of a metallurgical vessel including an inclined foundation and ways on the inclined foundation to support the carriage of a mobile cleaning device. The mobile cleaning device has a carriage which moves along the ways on said inclined foundation. The mobile cleaning device has a pivotally mounted boom with a rotary shaft having a cutting head mounted on its end and bits on the cutting head. A support stand is located adjacent the upper end of the inclined foundation for holding a metallurgical vessel in a stationary position during cleaning.

Abstract: Apparatus for machining splines on the internal surface of a tubular member comprising cutter means for forming the splines on the internal surface; a carrier for the tubular member for enabling the tubular member to be moved in an axial direction relative to the cutter means; and means for angularly indexing the cutter means relative to the tubular member whereby splines at angularly predetermined intervals can be provided around the interval circumference of the tubular member.

Abstract: A remotely controlled, hydraulically operated cutter apparatus for use in a conduit includes control panel for generating a plurality of control signals for controlling the operation and a source of pressurized hydraulic fluid. Valves are provided for receiving both the pressurized fluid and the control signals, and for distributing the received fluid in accordance with the received control signals. A hydraulically powered cutter motor located within the conduit and including a cutting tool receives hydraulic fluid from the valves for driving the cutting tool. The cutter motor is supported within the conduit by a structural unit. A first hydraulically actuated cylinder is included for receiving hydraulic fluid from the valves and for centering and holding the structural unit in a fixed axial position within the conduit.

Abstract: The invention in question is a repairing machine, which is suited to repairing damaged conduits which are inaccessible for repair work. This repairing machine is remote-controlled and monitored with television cameras. At the head of the driving carriage, various devices, which are necessary for the repairs, can be attached to a motor-driven rotatable toolhead. A simple construction of the movable head has made it possible to accomplish all of the necessary movements with uncomplicated mechanics, and at the same time, to forego a tedious slide coupling for the control lines without letting them get tangled with the device. Therefore, with this invention, the production costs for the whole device could be lowered and, likewise, the proneness to repairs could be reduced.

Abstract: Apparatus for removing obstructions from pipelines, such as sewers, comprises support means, motor means carried by the support means, cutter means adapted to be operated by the motor means, and means for locking the support means in a pipe, adjacent an obstruction whereby the apparatus may be locked in a predetermined position, and the motor means operated to drive the cutter means and remove the obstruction. The motor means may comprise an hydraulic motor. The cutter means may be a rotary saw. The means for locking the support means in position may comprise at least one hydraulic jack.

Abstract: Device for the internal machining of a tube comprising a mobile assembly which can be located in the tube and having a first part with at least two centering bearings and two rotors, and a second part linked in radially sliding manner with the first part and having a machining tool able to machine the interior of the tube, one of the said rotors driving the machining tool via a transmission shaft and the other of the said rotors rotating said second part; as well as a fixed assembly arranged around the tube and having first and second magnetic devices, each establishing a rotary magnetic field able to rotate the two rotors and a third magnetic device establishing a rotary magnetic field able to displace the said second part radially with respect to the first part, while rotating in phase with the second part.

Abstract: Disclosed is apparatus and method for a system useful in establishing a metal to metal seal between conduit joints in wells. A milling tool having means controlling down force on and positioning the cutter is used to cut and/or finish a seat on a shoulder in a well conduit, which will mate and seal with metal seal surfaces on seal units lowered on conduits into the well. One seal unit has elastomeric seals in addition to the metal seals.

Abstract: The invention describes a cutter which is for positioning in an underground pipe which is too small for man entry. The cutter is for cutting holes in previously applied pipe lining which cover lateral connections. The cutting must be controlled from above ground. Flexibility and positionability is achieved by mounting the cutter head at the free end of a boom body, the other end of which is mounted through a universal joint to a mounting so that the boom can swing in any direction. The cutter is controlled in its movement by coupling it to a master unit located and controlled above ground.

Abstract: An elongate body (1) comprises an assembly of two body portions (2, 3) and contains a plurality of intermeshing gearwheels (12A to 12D) with the first gearwheel (12A) having teeth projecting through an end opening (10) to be driven by an external toothed wheel, and with the last gearwheel (12D) being disposed to drive a milling bit (15) which projects through a side opening (11).

Abstract: The de-burring tool is designed for the de-burring of the edges of holes preferably in curved or oblique surfaces of a work piece and consists of a rotationally-driven tool holder on which one or more cutters are arranged which are controlled in axial displacement. Control is achieved in that the tool holder itself is axially displaceably mounted in a fixed base body, in which the axial displacement of the tool holder is achieved through a cam which follows the curvature of the edge of the hole.

Abstract: A remote cutting tool for insertion into an underground sewage pipe for trimming branch line stub ends that extend into the sewage pipe. The cutting tool comprises a sled adapted to be drawn through the interior of the pipe by cables attached thereto. A cylindrical cutting bit is driven by a hydraulic motor, the motor and bit being retained on the sled through a hydraulic jack ram. The jack ram facilitates the axial movement of the motor and bit with respect to the sled as required to effect branch stub cutting. Expandable pneumatic sleeves are provided on the sled which, when inflated, lock the sled in fixed orientation in the pipe prior to each cutting operation. A guide member is positioned over the pneumatic sleeve adjacent the point of intended cutting to deflect the sleeve in the opposed direction and to align the cutting bit in close proximity to the sewer pipe wall at the point of stub pipe entry.

Abstract: A manipulator head for the remotely controlled positioning and operation of a tool in the interior of a pipe includes:first support flanges having guiding elements and clamping devices;a tubular tool holder frame having second support flanges interconnecting the first support flanges and being rotatably supported thereby;a rotating tool including a milling cutter at an assembly opening in the tool holder for machining the inner wall surface of a pipe;a first guide rail attached to the inner wall surface of the tool holder, a first slide axially movable on the first guide rail, a first driving device coupled to the first slide for axially moving the tool;a second guide rail fastened to the first slide, a second slide radially movable on the second guide rail, a second driving device coupled to the second slide for radially setting the tool;the milling cutter being fastened to the second slide, a third driving device coupled to the milling cutter for a working motion of the tool; anda fourth driving device disp

Abstract: A remotely controllable travelling robot for operation inside a pipe or bore-hole has a tool mounting assembly (22) which is rotatable in support structure (14, 16) about a longitudinal axis. The support structure (14, 16) is mounted on a pair of skids (10, 12) by means of a hydraulically driven elevator mechanism including rams (32) mounted on the skids 10, 12 which lift the support structure (14, 16) to a required height so as to place the longitudinal axis approximately in coincidence with the axis of the pipe or bore-hole. A tool mounting head (80) forming part of the tool mounting assembly (22) is itself hydraulically powered for tilting about a transverse axis and for moving transversely relative to the longitudinal axis along a transverse bar (88) fixed in a tool mounting assembly casing 60.

Abstract: A remotely controlled, hydraulically operated cutter apparatus for use within a conduit includes a control for generating a plurality of control signals for controlling the operation of a source of pressurized hydraulic fluid. Valves are provided for receiving both the pressurized fluid and the control signals and for distributing the received fluid in accordance with the received control signals. A hydraulically powered cutter motor located within the conduit and including a cutter tool receives the hydraulic fluid from the valves for driving the cutter tool. The cutter motor is supported within the conduit by supporting members. A first hydraulically actuated cylinder is included for receiving hydraulic fluid from the valves and for holding the supporting members in a fixed axial position within the conduit.

Abstract: A cam controlled grinding machine in one embodiment of which the spindle is supported for rotation and lateral movement within a nest of three annular rings. Advantageously, roller bearing arrays between the spindle and the first annular ring, the first and second annular ring, and the second and third annular ring permit the spindle and first and second annular rings to rotate relative to one another while the third annular ring is fixed in position. In order to permit lateral movement of the spindle, the centers of each roller bearing array are non-coincident. In a second embodiment the spindle is in effect mounted on an articulated arm having two degrees of freedom. As a result, the spindle can be moved laterally in two dimensions in response to movement imparted to it by the action of a drive follower and cam. In a third embodiment, an annular bearing plate is attached to the spindle and is supported for lateral movement by a plurality of balls contained underneath the bearing plate.

Abstract: A method for re-establishing side connections to an underground pipe after the same has been lined with a rigid lining of synthetic resin is disclosed, and in the method a cutter of the unit located in the pipeline moves in accordance with a pre-programmed contour which matches the contour of the side connection, thereby effectively and quickly to re-establish the side connection.The pre-programmed arrangement may be generated by sensing the side connection profile prior to the lining operation.

Abstract: The attachment is to be fitted to a lathe or a milling machine. It is designed for slotting (keyway cutting) and grooving operations. It comprises an elongated boxshape housing having a longitudinally extending shaft journaled therein. The rear end of the shaft is operatively connected to an electric motor, while the front end carries a first bevel gear which meshes with a second bevel gear fixed to a hollow spindle and perpendicular thereto journaled in the front end of the housing. A rotary cutting tool is removably fixed within the spindle and projects laterally of the housing. The attachment can be detachably secured to the carriage of a lathe or to the head portion of a milling machine.

Abstract: An internal grinding machine comprising a work head adapted to rotate about a selected axis and to be displaced in a direction perpendicular to that axis. The work head includes a workpiece holding fixture having a fixed lower jaw and an upper jaw displaceable from an open position to a closed position for clamping the outer periphery of a cylindrical workpiece having a longitudinally extending slot along the length thereof. The fixed jaw has a longitudinally extending key to be located within the keyway of the workpiece. A grinding spindle adapted to be rotated about and displaced along its axis includes a grinding wheel having a plurality of annular, outwardly projecting tapered grinding portions for effecting stock removal from a clamped workpiece and cutting the workpiece into a selected number of annular rings, as the workpiece holding fixture is advanced relative to the grinding wheel from a start position to a finish position.

Abstract: The invention provides a cutter device for use especially in an underground pipeline or passageway such as a sewer which has been lined with a rigid resin lining, the cutter device serving to cut the lining where it covers lateral connections which must be re-opened. The cutter device according to the invention provides a cutter with a cutting bit which can be moved in an orbital fashion to enable the line of action of the cutter bit to maintain its angularity with respect to the angularity with which the lateral meets the main pipeline or passageway. The cutter bit preferably is a rotatable cutter bit, but in the alternative it may be for example a jet of liquid.

Abstract: A milling tool for forming recesses, such as an undercut in a borehole, in masonry, concrete and similar material structures includes a tool shaft with a bearing pin extending outwardly from one end of the shaft and with the axis of the pin offset eccentrically to the axis of the tool shaft. A freely rotatable annular milling head is positioned on and encircles the bearing pin. The outside surface of the milling head has cutting edge members.

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: An apparatus for in-place grinding of the inner surface of huge cylinders mprises two adjustable spider ring assemblies which support a rotating rail assembly. A cage assembly is mounted on and rotates with the rail assembly and carries a grinding unit for grinding the inner surface of the cylinder.

Abstract: The invention is directed to an improved boring and facing apparatus for performing in-situ machining on nuclear reaction feedwater inlet nozzles. The apparatus comprises a boring machine mounted upon a main frame which main frame is suspended from a structure mounted above the plane in which the inlet nozzle is located. Means are provided for adjusting the boring machine to permit a tool to operate along the center line axis of the inlet nozzle.

Abstract: A grinder is supported within a pipe, the support being arranged to adjust the movement of the head of the grinder radially and axially of the pipe axis to bear against internal cracks in the pipe wall.

Abstract: A thermoplastic corrugated drainage tube comprising annular peaks and valleys and a plurality of drainage openings internally cut about the circumference of each valley, the openings in each valley aligned with the openings in successive valleys along helical lines described by said openings. The method of forming the drainage openings comprises placing a cutting tool in the interior of the tubing and rotating the tool while moving the tubing axially past the tool. The cutting tool comprises a body having a plurality of radially projecting cutters spaced equidistantly about the cutter body and means for rotating the tool.

Abstract: An apparatus for forming a port in a liner installed in a conduit having a lateral opening inwardly overlaid by the liner so that the port coincides with the lateral opening, including a carriage adjustably positionable longitudinally within the liner adjacent to the lateral opening in the conduit; a brake for locking the carriage in fixed position in the conduit; a power driven port forming tool borne by the carriage in substantial radial relation to the liner for adjustable movement outwardly to liner engagement and inwardly to retraction therefrom, for adjustable movement longitudinally of the carriage, and for adjustable rotational movement about an axis longitudinally of the carriage; control means for controlling the position of the tool on the carriage from a position remote from the carriage; and a television system having a camera mounted on the carriage having a view of the tool and a viewing screen at said remote position.

Abstract: A cutting apparatus with a vertical drive mechanism for in place machining f a valve seat which may include an annular turntable adapted to be rotatably mounted on the valve above the valve seat. A feed shaft is mounted through the turntable so as to be rotatable therewith, and a bottom of the feed shaft is adapted to receive a cutter for machining the valve seat. The vertical drive mechanism is mounted on the feed shaft and includes a nut threaded in the feed shaft and a gear combination. The gear combination may include a first portion which is fixedly connected to the nut, a second portion which operatively engages the first gear portion, and a third portion which operatively engages the second gear portion, the third gear portion being mounted for rotatable slidable friction engagement about the nut.