in reference to fig1 - 3 a portable flange facer according to one aspect of the present invention comprises a spindle 10 having at its lower end 12 , and integral therewith , a mounting mechanism 14 . lower end 12 of spindle 10 is held within a bore 16 of pipe 18 by mounting mechanism 14 having upper clamp jaws 20 and lower clamp jaws 22 which are extended radially to contact the interior of pipe 18 in order to secure spindle 10 centrally within the bore 16 of pipe 18 ; the upper and lower clamp jaws 20 and 22 are horizontally and slidably disposed within bores 19 in spindle 10 . in the presently described embodiment there are four upper clamp jaws and four lower clamp jaws ; however , it is understood that a greater or lesser number of clamp jaws could be used without departing from the scope of the present invention . further , the upper and lower clamp jaws are equiangularly distributed ; however , such a relationship is not essential to operation of the present embodiment . upper and lower clamp jaws 20 and 22 are generally cylindrical , slightly rounded at an end 24 with which contact is made with the interior of pipe 18 , and cut angularly , in this embodiment at 45 degrees , at an opposite end 26 interior to spindle 10 . upper jaw actuators 30 are vertically and slidably disposed within bores 31 in spindle 10 , have a substantially flat upper end 32 , an angularly cut lower end 34 similar to that of upper jaw clamps 20 , and are positioned such that the lower end 34 of actuators 30 faces the end 26 of the corresponding upper jaw clamp 20 . forcing upper actuators 30 downward and against upper clamp jaws 20 causes upper clamp jaws 20 to move radially outward toward the interior of pipe 18 . this forcing action is performed by push rods 36 which are vertically and slidably disposed within bores 37 in spindle 10 , positioned to contact upper ends 32 of respective actuators 30 , and moved vertically downward by upper jack screws 38 threadably engaged within spindle 10 . note , as is illustrated in fig8 that the cross sections of bores 31 and 37 are overlapped in the area of actuators 30 . bores 31 are dimensioned such that actuators 30 may only move vertically . a recessed area 40 is provided for each of the upper jaw actuators 30 to allow actuators 30 to extend slightly below upper clamp jaws 20 thereby increasing the radial extension of jaws 20 in response to the downward motion of actuators 30 . lower clamp jaws 22 are each spaced below and vertically aligned with a corresponding upper clamp jaw 20 and are caused to move radially outward by lower jaw actuators 44 in a manner similar to that of upper clamp jaws 20 except that lower jaw actuators 44 are angularly disposed within spindle 10 and are acted upon directly by lower jack screws 46 which are threadably engaged within spindle 10 , i . e ., no push rod is employed . upper and lower clamp jaws 20 and 22 would suitably be provided in a variety of lengths corresponding to various pipe diameters . spindle 10 is secured centrally within the bore 16 of pipe 18 in a one step setup by selecting a set of upper and lower clamp jaws of suitable length , placing them within bores 19 of spindle 10 , and placing the lower end 12 of spindle 10 within pipe 18 . proper adjustment of upper and lower jack screws 38 and 46 will result in alignment of a central axis 50 of spindle 10 with a central axis 52 of pipe 18 and will as well secure spindle 10 within the bore 16 of pipe 18 . the upper clamp jaws 20 are set by turning upper jack screws 38 , accessible at the top of spindle 10 , while lower clamp jaws 22 are set by turning lower jack screws 46 , accessible near the opening of pipe 18 . when spindle 10 is secured in such manner to pipe 18 it may be considered to be stationary with respect to pipe 18 , that is to say spindle 10 does not rotate with respect to pipe 18 but does provide a structure about which rotary portions , discussed hereinafter , of the flange facer may rotate . a rotary union 60 is rotatably mounted on an upper end 62 of spindle 10 and employed to supply compressed air from an external air hose 64 , via air fitting 63 rigidly affixed to spindle 10 , to a pneumatic motor 66 via a bore ( not shown ) in spindle 10 , an annular channel 61 defined between spindle 10 and rotary union 60 , and a local air hose 68 . pneumatic motor 66 is mounted upon a main body 70 and used to rotate main body 70 about spindle 10 upon rotational bearings 72 . pneumatic motor 66 provides torque to a motor drive gear 74 . as best seen in fig2 motor drive gear 74 is meshed with a lower jack gear 76 . upper jack gear 78 , rigidly affixed to and sharing a common axis of rotation with lower jack gear 76 , is meshed with stationary bull gear 80 which is rigidly affixed to spindle 10 . actuation of pneumatic motor 66 results in rotation of main body 70 about spindle 10 while rotary union 60 prevents twisting of external air hose 64 during such rotation . a feed pump 90 , having a feed pump piston 92 , is secured to the main body 70 . a feed cam 94 fixed to spindle 10 acts upon a cam follower 96 , attached to the feed pump piston 92 , as main body 70 rotates about spindle 10 while the cam follower is held against the feed cam 94 by a follower return spring 98 . feed pump 90 suitably includes a reservoir 100 ( fig3 ), a spring loaded reservoir piston 102 , a 1 - 2 psi refill check valve 104 , and a 300 psi relief check valve 106 . a hose 108 couples feed pump 90 and a removable feed slave unit 110 . feed slave unit 110 includes a slave piston 112 . pistons 92 and 112 move simultaneously due to their being coupled by hydraulic fluid in hose 108 . a pin 114 is held against piston 112 by a return spring 116 , having a spring cap 117 . spring 116 is disposed upon a feed rate adjustment knob 118 threadably engaged with feed slave unit 110 . cam 94 initially causes piston 92 to be moved to the right of fig2 compressing spring 98 and causing piston 112 to move to the right of fig2 . pin 114 is moved to the right , and spring 116 also is compressed . subsequently , cam 94 allows follower 96 to move to the left , and spring 98 urges pistons 92 and 112 to the left . spring 116 urges pin 114 to the left . the position of the feed rate adjustment knob 118 determines the extent to which pin 114 moves to the left of fig2 when piston 112 moves to the left . pin 114 comprises an end of a lever arm 120 coupled , via a unidirectional roller clutch 122 , to a sleeve 123 which is vertically and rotationally disposed within feed slave unit 110 . as slave piston 112 moves back and forth in response to the flow of hydraulic fluid in hose 108 and the pressure of return spring 98 , pin 114 is similarly caused to move back and forth . in response thereto roller clutch 122 , being unidirectional , causes the sleeve 123 to rotate in only one rotational direction , clockwise as seen in fig2 . ( in fig4 and 5 , arrow 126 indicates the direction of rotation of arm 120 due to return spring 116 while arrow 128 shows the direction of rotation of arm 120 due to slave piston 112 .) to disable rotation of sleeve 123 by the action of pin 114 , knob 118 may be adjusted such that pin 114 is no longer held against piston 112 . in reference to fig4 and 5 , a feed input shaft 124 is seen to be disposed rotationally within sleeve 123 . shaft 124 is provided with a removable crank handle assembly 130 for manual rotation thereof . crank handle assembly 130 includes an engagement box 132 having pins 134 engageable within slots 136 on sleeve 123 . crank handle assembly 130 is slidable on feed input shaft 124 between a disengaged position , fig4 and an engaged position , fig5 . in fig4 sleeve 123 is disengaged from shaft 124 and crank handle assembly 130 may be used to rotate feed input shaft 124 in either rotational direction as indicated by arrows 138 . in fig5 sleeve 123 is engaged , by virtue of insertion of pins 134 within slots 136 , with shaft 124 . manual rotation of feed input shaft 124 is thereby restricted by roller clutch 122 to a direction indicated by arrow 140 . as best seen in fig6 at an end opposite crank handle 130 , feed input shaft 124 includes a feed worm 150 meshed with a feed worm gear 152 . feed worm gear 152 is mounted upon a pinion drive shaft 160 . rotation of feed input shaft 124 , in either rotational direction , results in rotation of feed worm gear 152 and pinion drive shaft 160 . returning to fig1 pinion drive shaft 160 is rotatably disposed within main body 70 and has a pinion gear 162 mounted thereon . a turning bar 164 is slidably and horizontally disposed within main body 70 and has a longitudinal rack gear 166 formed therein , the rank gear 166 being meshed with the pinion gear 162 . the diameter of spindle 10 is decreased in the vicinity of turning bar 164 to form a peripheral groove 167 . turning bar 164 is received in groove 167 so as to place turning bar 164 close to the central axis 50 of spindle 10 . a tool head 168 ( fig2 ) is mounted upon an end of the turning bar 164 and secures a cutting element 170 ( fig7 ) thereat for the purpose of machining a flange surface 180 . radial positioning of the cutting element 170 is accomplished by rotation of feed input shaft 124 . specifically , rotation of feed input shaft 124 in a first direction causes the turning bar 164 to move rightward , as viewed in fig2 while rotation of feed input shaft 124 in a second direction causes turning bar 164 to move leftward , as viewed in fig2 . referring again to fig7 tool head 168 suitably includes a depth shaft 190 coupled by internal gear means ( not shown ) to a vertically disposed rack gear 192 having cutting element 170 mounted thereon . depth shaft 190 is rotated to adjust the depth of cut , i . e ., extension of cutting element 170 toward flange face 180 . rack gear 192 is mounted upon a rotatable member 194 which may be rotated to adjust the angle of cut and set in a particular position by set screws 196 . automatic down feed capability is provided by removing feed slave unit 110 and crank handle assembly 130 ( fig2 ) and mounting them on tool head 168 . feed slave unit 110 receives depth shaft 190 in a manner similar to that in which it receives feed input shaft 124 and causes depth shaft 190 to rotate automatically as main body 70 is rotated about spindle 10 . in addition , crank handle assembly 130 may be utilized to manually turn depth shaft 190 . the feed slave unit 110 is adapted to be mounted at various locations on the portable lathe in order to provide automatic radial feeding and automatic axial feeding . radial feeding is provided when the feed slave unit 110 communicates with feed input shaft 124 while axial feeding is accomplished by mounting the feed slave unit 110 on the depth shaft 190 . although the feed slave unit 110 is unidirectional in nature , it can be employed conveniently to provide selectively either outward or inward automatic radial feeding as well as either upward or downward automatic axial feeding . the feed slave unit 110 may be mounted in a non - inverted position to provide either outward radial feed or downward axial feed , or it may be flipped over to an inverted position , to reverse its output direction , to provide either inward radial feed or upward axial feed when coupled to the appropriate shaft . thus , the versatility of the hydraulic feed system provides a multitude of functions while requiring but one feed source or feed pump . to operate the portable flange facer , end 12 of spindle 10 is secured centrally within bore 16 of pipe 18 as hereinbefore described . this one step setup operation can be performed by an experienced operator in less than ten minutes . if a re - surfacing operation is to be performed , then the radial position of cutting element 170 is manually set to the inner diameter of the area to be resurfaced and the depth and angle of cut are set by appropriate adjustment of tool head 168 . feed rate adjustment knob 118 may be adjusted to set an infinitely variable feed rate within the range of 0 to 0 . 0813 centimeters per revolution . actuation of pneumatic motor 66 causes rotation of main body 70 about spindle 10 as well as automatic and incremental outward radial movement of cutting element 170 . when the radial position of cutting element 170 reaches the outermost diameter of the area to be resurfaced , then the operation may be repeated to effect a deeper cut or may be terminated if the previous cut resulted in satisfactory resurfacing of the flange face 180 . grooves for o - rings and angle chamfers may be formed in flange face 180 by first selecting a suitable cutting element , adjusting the proper cut angle , and mounting the feed slave unit 110 on tool head 168 , as hereinbefore described , for automatic down feed . actuation of motor 66 then causes a circular groove to be formed in flange face 180 while the feed slave unit 110 automatically increments the depth of cut according to the current setting of adjustment knob 118 . in reference to fig9 an alternative clamping mechanism 220 is suited for large diameter pipes and includes upper jaws 222 and lower jaws 224 which are slidable within radial bores 225 in a lower section 226 of a spindle 228 . lower section 226 is bolted to an upper section 230 of spindle 228 . each of upper and lower jaws 222 and 224 is provided , at its radial outer end , with a jacking bolt 232 threadably engaged therein and having a head 233 . jacking bolts 232 are adjustable to move heads 233 radially outward of spindle 228 to bear against the interior of a pipe ( not shown ) to be machined . jaw spacers 234 may be inserted in bores 225 so as to radially extend the adjustable range of bolts 232 . in this particular embodiment , there are four upper clamp jaws 222 and four lower clamp jaws 224 with both upper and lower clamp jaws being equiangularly distributed . however , such an arrangement is not essential to the operability of the lathe . a balance arm 236 having a counter - weight 238 , positionable along the length thereof , is horizontally and slidably disposed within a main body 240 . the balance arm 236 allows smooth chatter - free turning while machining vertical flanges . this second embodiment is in all other aspects , both structural and operational , substantially identical to the previously described embodiment with the exception of the modified clamping arrangement and the balance arm . although lower section 226 of spindle 228 is bolted to upper section 230 thereof , the portable flange facer is operated without detaching lower section 236 from upper section 230 . sections 226 and 230 are bolted together solely for ease of manufacture . the portable lathe described herein has a number of advantages and among those advantages are the following : the feed rate is infinitely adjustable and thereby provides greater feeding precision , the lathe is compact and is therefore more readily adaptable for tight working space , and the motor and gearing are all completely inside the main body and are therefore protected from metal shavings and contaminants present on most work sites . by placing the motor on the main body and not on the spindle , the overall height of the lathe is reduced . because all clamp jaws are individually adjustable in length , centering of the spindle is more easily accomplished . also dual level clamping provides the spindle with greater rigidity when mounted inside the pipe bore . in either embodiment , there is no need to mount a separate clamping mechanism ; the entire lathe is mountable in one step . the flange facer , in either embodiment , may be operated in whatever vertical , horizontal or angular position is necessary on a flange face . it should be understood that reference herein to vertically and horizontally disposed elements and reference to element names such as upper and lower clamp jaws are for convenience and clarity . while plural embodiments of the present invention have been shown and described , it will be apparent to those skilled in the art that many other changes and modifications may be made without departing from the invention in its broader aspects . the appended claims are therefore intended to cover all such changes and modifications as fall within the true spirit and scope of the invention .