US2666989A

US2666989A - Multiple spindle engraving and the like machine tools

Info

Publication number: US2666989A
Application number: US119281A
Authority: US
Inventors: Allen D Gunderson
Original assignee: George Gorton Machine Co
Current assignee: George Gorton Machine Co
Priority date: 1949-10-03
Filing date: 1949-10-03
Publication date: 1954-01-26
Anticipated expiration: 1971-01-26

Description

Ian. 26, 1954 A. D. GUNDERSON 2,666,989

MULTIPLE SPINDLE ENGRAVING AND THE LIKE MACHINE TOOLS Filed Oct. 3, 1949 ll Sheets-Sheet 1 Emu l ilmmmfili H91 I I" I N VEN TOR.

Jan. 26, 1954 A. D. GUNDERSON 2,666,989

MULTIPLE SPINDLE ENGRAVING AND THE LIKE MACHINE TOOLS Filed 001:. 3, 1949 ll Sheets-Sheet 2 quszu- MA dams ( ig 32 INvENfOR.

Jan. 26, 1954 A. D. GUNDERSON MULTIPLE SPINDLE ENGRAVING AND THE LIKE MACHINE TOOLS ll Sheets-Sheet 3 Filed Oct. 5, 1949 Jan. 26, 1954 A. D. GUNDERSON MULTIPLE SPINDLE ENGRAVING AND THE. LIKE MACHINE TOOLS ll Sheets-Sheet 4 Filed Oct. 5, 1949 Jan. 26, 1954 A. D. GUNDERSON MULTIPLE SPINDLE ENGRAVING AND THE LIKE MACHINE TOOLS Filed Oct. 5, 1949 ll Sheeis-Sheet 5 INVENTOR.

Jan. 26, 1954 A. 0. GUNDERSON 2,666,989

MULTIPLE SPINDLE ENGRAVING AND THE LIKE MACHINE TOOLS Filed Oct. 3, 1949 ll Sheets-Sheet 6 I a so Jan. 26, 1954 A. D. GUNDERSON MULTIPLE SPINDLE ENGRAVING AND THE LIKE MACHINE TOOLS Filed Oct. 5, 1949 ll Sheets-Sheet 7 I N VEN TOR.

Jan. 26, 1954 A. D. GUNDERSON 2,666,

MULTIPLE SPINDLE ENGRAVING AND THE LIKE MACHINE TOOLS Filed Oct. 3, 1949 ll Sheets-Sheet 8 0h aw L L wm 8.5L 8 m T a WW/WMVZ 4? P W w-$k m m Jan. 26, 1954 A. D. GUNDERSON MULTIPLE SPINDLE ENGRAVING AND THE LIKE MACHINE TOOLS ll Sheets-Sheet 9 Filed Oct. 5, 1949 Jan. 26, 1954 A. D. GUNDERSON 2,666,989

MULTIPLE SPINDLE ENGRAVING AND THE. LIKE MACHINE TOOLS ll Sheets-Sheet 10 Filed Oct. 3, 1949 Jan. 26, 1954 MULTIPLE SPINDLE ENGRAVING AND THE LIKE MACHINE TOOLS Filed Oct. 3, 1949 A. D. GUNDERSON 11 Sheeis-Sheet 11 INVENTOR.

Patented Jan. 26, 1954 MULTIPLE 'SPIN'DLE ENGRAVING AND THE LIKE MACHINE TOOLS Allen D. Gunderson,

George Gorton Machine 00., corporation of Wisconsin Racine, Wis., assignor to Racine, Wis., a

Application October 3, 1949, Serial No. 119,281

27 Claims.

This invention relates to certain improvements in multiple spindle engraving and the like machine tools; and the nature and objects of the invention will 'be readily recognized and understood by those skilledin the arts involved from the following explanation and detailed description of the accompanying drawings illustrating what I'now believeto-beapreferred embodiment or mechanical expression of the invention and the several featuresthereo'f, from among various other embodiments, designs, arrangements, adaptations, forms, combinations and constructions, of which the invention is capable within the broad spirit andscope thereof'as defined by the appended-claims.

By my invention I'have provided a tracer controlled machine tool organization particularly adapted, but not limited," to engraving operations, which is characterizedby-the'use of multiple cutter spindles with a work table mounted for universal lateral movements relative to the cutter spindles, and a movement "transmitting mechanism of the traceractuated, pantograph type coupled directly to theworktable for actuating the table to move simultaneously multiple work pieces mounted thereon relative to the multiple spindles, respectively, in sealed reproduction of the movements of-thetracer-in scanning a-master to be reproduced'on the work-pieces.

A general obj'ectof-th'e invention is to provide a design and arrangement of such a machine organization, and a-construction and combination of'thecomponents thereof, to present an extremely'stable and rigid machine which is highly sensitiveand responsive'in operation and capable of reproducing with precision and accuracy on a work :piece 'or simultaneously on multiple work pieces, a scaled reproduction in two dimensions of the' master design.

And a further general object-is to'provide such a machine with controls which substantially eliminate the possibility "of operator errors, so that reproducing'orengraving operations may be carried out on multipleworkpieces with a minimum of work spoilage and 'atrelatively high rates of production without requiring highly skilled operators.

Such a-machine organization, incarrying out the foregoing-general objects,.includes the following primary features:

A plurality (itself-contained motorized spin- .le units together with 'a' mounting therefor, by which such units maybe individually and independently "removed from "and replaced in mounted p'os'itions; -andbywhich; when mounted,

the units are capable of individual and inde-,- pendent adjustments'in directions axially and/or radially relative to each other;

Mechanism for feeding the multiple cutter spindle units simultaneously in precise synchronization to and from operative working positions relative to multiple work pieces, respectively, mounted on a universally laterally movable Work table.

Electra-pneumatic mechanism and operating controls therefor, for actuating the cutter spindle unit feeding mechanism.

The mounting directly on an adjustable sup.- porting knee structure of a table unit of the universally laterally movable work table type for movement as a unit with the knee-structure; and the design and construction of such a work table unit which provides an arrangement of slide rods mounted in linear, antifriction bearing assemblies to provide a minimum friction, highly sensitive mounting for universaLlateral movements of the work piece supporting table.component of the table unit.

The combination with such a sensitive" type work table, of a pantograph mechanism directly coupled therewith by which the work table is universally laterally movable in sealed reproduction of the movements imparted to the pantograph mechanism by the tracer in scanning a master;

The provision for the adjustment bodily of the work table unit with the supporting knee structure in either direction transversely of the gen eral plane of the pantograph mechanism, without changing the position of the pantograph mechanism or disconnecting it from the uni,- versally laterally movable-work supporting table component of the unit;

Mechanism for mounting onthe universally laterally movable table component of the work table unit, multiple work pieces in operativerelation with the multiple cutter spindles, respectively, and for indexing simultaneously in-precise synchronism, such multiple work piecesto present different portions thereof in operative working position relative to the spindle units.

Electro-pneumatic means for operating .the work piece indexing mechanism ,to effectsimultaneous indexingof multiple work pieces.

The system of interlocks for the work indexing actuating means and cutter spindle unit feedactuating means by which work indexing isprevented when the cutter spindle units are fed to and. are in positions inoperative working relation with the work pieces on the work table, andby which work indexingtmay :beefiected o rlmwhen the cutter spindle units are in positions removed from operative working relation with the work pieces.

The provision of an indexable master unit for mounting a plurality of different patterns with such master unit mounmd for selective indexing to position a desired pattern for scanning by a tracer style mounted for movements between position in scanning engagement with a pattern and position out of scanning engagement with the pattern.

The system of interlocks by which the master unit is locked against indexing when the cutter spindle units are fed to and are in positions in operative working relation with work pieces on the work table, and by which the master unit may be indexed only when are in positions removed from operative relation with the work pieces, so that, indexing of the master unit and indexing of the work pieces may be effected simultaneously and only when the cutter spindle units are out of work operating ositions relative to the work pieces;

The system of interlocks by which the cutter spindle unit feed actuating means is controlled by the operation of the tracer to and from pattern engaging position, to cause leed of the spindle units to working position with the tracer in pattern engaging position and to cause feed of the spindle units to non-working position when the tracer moves to pattern disengaging position; and by which the spindle unit feed actuating means is rendered inactive to lock the spindle units against feed when the tracer is in disengaged position.

With the foregoing and various other objects, features and results in view, which others will be readily apparent from the following explanation and detailed description of the illustrated example of the invention, my invention consists in certain novel features in design and construction and in combinations and sub-combinations of parts and elements, all as will be more particularly referred to and specified hereinafter.

Referring to the accompanying drawings in which similar reference characters refer to corresponding parts throughout the several figures thereof:

Fig. l is a perspective view of a tracer controlled, multiple spindl engraving machine embodying the invention, multiple work pieces being shown on the table supported work indexing mechanism and the multiple cutter spindles being shown in their lowered, operative positions relative to the work pieces.

Fig. 2 is a view in front elevation of the machine of Fig. l, a portion only of the master wheel being shown.

Fig. 3 is a view in side elevation hand side of the machine of Fig. 1.

Fig. 4 is a view in side elevation taken of the left hand side of the machine of Fig. 1.

Fig. 5 is a view in horizontal section taken as on the line 55 of Fig. 2, and showing in top plan the work table, work indexing mechanism, tracer controlled pantograph and master wheel.

Fig. 6 is a detail view in vertical section showing the pivotal coupling of the pantograph actuated linkage to the work table, and taken as on the line 6-6 of Fig. 5.

Fig. "I is a vertical section through the pantograph mechanism and a portion of hte pivotal coupling for connecting the pantograph with the work table, taken as on the line 'l---'! of Fig. 5.

Fig, 8 is a vertical section through a pivot of of the right 4 the pantograph, taken as on the line Fig. 5.

Fig. 9 is a vertical sectional view taken as on the line 9-9 of Fig. 5.

Fig. 10 is a vertical sectional view taken as on the line Ill-40 of Fig. 5.

Fig. 11 is a top plan view of the sensitive work table of the machine of Fig. 1, and showing in dotted lines the mounting and arrangement of slid rods and linear ball bearings for the table.

Fig. 12 is a vertical longitudinal section taken as on the line l2|2 of Fig. 11, showing particularly the mounting of the table directly on the supporting knee of the machine; the work indexing mechanism mounted on the table being shown p in front elevation.

Fig. 13 is a perspective view, partly in section, of one of the linear ball bearings of the mounting arrangement for the sensitive table.

Fig. 13a is a detail vertical section through a spindle unit mounting head showing the feed anti-backlash spring and plunger.

Fig. 14 is a view in vertical, transverse section through the work table and its antifriction slide mounting, taken as on the line I l-l4 of Fig. 11, and also showing in vertical, transverse section one of the work mounting units of the work indexing mechanism.

Fig. 15 is a vertical transverse section taken as on the line l5-l5 of Fig. 11.

Fig. 16 is a view in side elevation of the left hand end of the cutter spindle head mounting structure, and showing, partly in side elevation and partly in vertical section, the'electro-pneumatic spindle feed actuating mechanism.

Fig. 17 is a detail view in horizontal section through one of the cutter spindle unit mounting heads, a gear train of the spindle unit feed being also shown.

Fig. 18 is a view in vertical section through one of the cutter spindle unit mounting heads showing a spindle unit mounted therein in operative engagement with the spindle unit feed mechanism.

Fig. 19 is a vertical sectional view through the master wheel and its mounting, the indexing plunger and plunger lock, and the tracer arm and tracer of the pantograph mechanism.

Fig. 20 is a purely schematic diagram of the electrical circuits and controlling interlocks therefor, and of the electro-pneumatic spindle feed and work indexing mechanism operating means and the air line system therefor.

An example embodiment of the invention and of the various features thereof, is illustrated and disclosed herein in the form of a tracer controlled, multiple cutter spindle engraving machine, designed for engraving simultaneously on multiple work pieces a scaled reproduction of a selected pattern from a series of patterns mounted on an indexable master unit. The invention is not, however, limited or restricted as to all of its features or as to all combinations or subcombinations thereof, to the example machine hereof, or to embodiment in or adaptation to machine organizations of either the multiple spindle type or of the engraving type.

General organization The example machine is of the vertical column and knee type in which a vertical column It extends vertically upwardly from a base H and mounts at the forward side thereof a vertically adjustable knee K. A slide block Illa is mounted at the forward side of column In for horizontal attests adjustments in either 'difectionon 'a covetah slide lflb (see Fig. 4) "at the upper end-of the'column; Slide block Illa provides at the'forward side thereof a vertically disposed dovetail slide Hlc which fits into a complementary vertical slide way formed in the rear side of structure K for adjustment of the knee structure on the slide block upwardly or downwardly relative to column Iii. The knee K is vertically adjustable upwardly or downwardly by means of "a vertical feed screw Hid carried by slide block Illa and rotated from hand wheel we carried by the knee. Horizontal adjustment transversely of the knee K on column I is effected through the medium of a lead screw Inf rotated by 'a hand crank mg.

The column 18 mounts 'or provides at its upper end a forwardly, horizontally extended cutter spindle unit mounting head structure "[2, which in this example is of greater width than the width of the column structure, as will be clear by reference to Fig. 2. At the forward, vertical side of structure [2, a series of vertically disposed spindle unit mounting heads H are adjustably mounted for receiving in vertically disposed position therein a plurality of motorized cutter spindle units S, respectively.

A work table unit T which provides a universally laterally movable work table mounting component, is mounted in horizontally disposed position directly on the upper side of the vertically adjustable knee K and is adapted to be carried by and moved vertically upwardly or downwardly as a unit with theknee toward or from spindle unit mounting heads H and the spindle units S mounted therein. The table unit T is sliclably mounted on knee K by a dovetail slide M which is received and slldably fitted into a complementary dovetail groove Ma formed in the under side of the base of table unit T. Thus, the table unit T may be adjusted on knee K in directions inwardly toward or outwardly from the column structure l0. Adjustments in or out of table unit T are effected by a usual feed screw Mb mounted on knee K, disposed longitudinally of slide I4, in threaded engagement with a usual feed screw nut (not shown) carried by table unit T. Feed screw Mb is rotated in either direction by a hand crank l lc at the outer end thereof at the forward side of knee K (see Figs. 1 and A. movement transmitting pantograph linkage mechanism P is pivotally mounted and hung from a fixed vertical pivot supported from column structure at, with the pantograph mechanism. P disposed horizontally and positioned at one side of the machine adjacent one end of the table unit T, in this instance the right hand side. Pantograph mechanism P is operatively coupled directly with the adjacent end of the universally laterally movable work piece mounting component of table unit T, for transmitting in sealed relation to such table component, the movements transmitted to the pantograph mechanism by a tracer style A mounted on and carried by a tracer arm of the pantograph mechanism.

At the forward, right hand side of the machine a master wheel M is mounted in vertically disposed position for rotation about a horizontal axis on the forward end of an arm structure H, which extends horizontally forwardly from the right hand side of column structure is (see Figs. 3 and 4); The master wheel M- is adapted to mount on and around the periphery thereof; a

series of "patterns ra selectiver'positioiiidg by indexing. rotation of said master wheel rd-r traciiig engagement by the 'tracerfstyle 'A. g

A multiple work met mounting and indexing rli'echanism B for indexing simultaneously work pieces mounted thereon, is mounted on the uni versa lly laterally movable work table forming component-or table unit "If. This mechanism 33 provides a pluralityof inclexable work holding fixtures on which" ma "be mouhted the work pieces W (see Figs. 1 and i). The work pieces W are positioned by the work holding fixtures with portions of the upper sides or edges thereof in vertical alignment'with rotary engraving or cutting tools C mounted in the lower ends of the cutterspindle's of the motorized spindle units S. U A pneumatic cylinder and piston unit D (see Figs. '4 and 16) is mounted on and forms a component of the work holding and indexing mechanism B, for operation to actuate the work indexing mechanism to index work pieces W mounted thereon into positions to present portions of the peripheral edges of such work pieces for work'- ing engagement with the engraving tools or cut-- ters C.

An air cylinder and piston] unit E is mounted on the left hand side or'end of head structure 52 (see Fig. 4) for operation to actuate the feed mechanism for the motorized spindle units S, to effect feed of these units simultaneously toward orfrom work table unit T to thereby project and retract the spindle mounted cutting tools C to and from working engagement with work pieces W mounted on the work holding and indexing mechanism B. The operation of the pneumatic cylinder unit D for actuating the'work piece indexing mechanism B, is controlled by as'olenoid operated air control valve unit F located in the air lines to the unit D -(see Fig. 3'). The actuation of control valveunit F is controlled by the e'nergiza tion and de-energizai'tion of the solenoid of the unit which in turn is controlled by suitable interlock switches, to be identified and described hereinafter, in the electrical circuits to the solenoid. of the valve unit.

The cylinder and piston unit E for actuating the feeding mechanism for the spindle units S, is controlled by a solenoid actuated air control valve unit G located in the air lines to unit E. The actuating solenoid of the air control valve unit G is energized and tie-energized under the control of interlock witches, to be identified and described hereinafter,- connected into the elec'- trical circuits to the solenoid of valve unit E.

Multiple spindle units and their mounting In the example machine "a series of four (4) self-contained, motorized spindle unit.- S are provided for mounting in vertically disposed position in the heads H1 The heads H are adjustably mounted on the forward side of structure 52 in vertically disposed positions above the work table unit T. n V

Referring now to Figs. 16, 17 and 18, in connection with Figs. lthe motorized spindle units S are identical in design, construction and dimensions and are interchangeable in the heads H. Each spindle unit S comprises a circular casing 20 within which there is mounted and contained a motorized spindle assembly 2|, which includes a motor and the cutter spindle 2 2 driven thereby and rotatively jou'rnaled therein position disposed axially of the casing. The-motorized-spindle assembly '2! slidably spindle unit mounting heads H within the casing 20 for mounted and contained movement axially in either direction therein. The position of the spindle assembly axially of casing 20 is adjustably determined by a micrometer adjusting mechanism 23 mounted at the upper end of casing 20 on an end cap 20a.

The arrangement of each motorized spindle unit S is such that the motorized spindle assembly 2| therein is located extending outwardly through one end (the lower end) of casing 20, with the cutter spindle 22 projecting outwardly beyond the assembly 2|. The outer end of cutter spindle 22 provides the operating end or nose of the spindle and mounts thereon any suitable cutting or engraving tool receiving and securing chuck or holder 22a, in which there may be mounted a cutting tool C.

Each of the cutter spindle unit mounting heads H is formed with an axial bore or passage 30 extending vertically therethrough and having a constant internal diameter which is substantially the same as the external diameter of the casing 20 of spindle unit S, so that, a unit S may be mounted therein in position extending therethrough with a slidable or running fit. A mounting base 3| is provided extending laterally or radially from the rear side of a head H, and this base 3| includes the opposite side vertical flanges 32 by which the head is adjustably mounted on the forward side of structure l2.

The forward side of the head mounting structure I2 is formed with a horizontal, longitudinally disposed channel |2a therein extending thereacross. Channel |2a is open at its forward side through the vertical, outer side surface |2b of structure l2. The surface |2b at opposite sides of channel |2a is formed to provide seating surfaces to receive and against which the base flanges 32 of heads H are adjustably secured. T-bolt slots |2c are formed in head structure l2 at opposite sides of channel In opening forwardly through seating surface IZb. T-slots |2c are disposed in parallel relation and extend longitudinally and substantially throughout the width, of the forward end of structure l2.

The spindle mounting heads H are adjustably mounted side by side in positions spaced along and extending forwardly from head structure l2, with the bores or openings 30 therethrough disposed vertically and in parallelism, by securing the base flanges 32 of each head to the seating surfaces I22) by the T-bolts 33 which are received and secured in the T-slots |2c. Thus the are independently adjustable relative to each other horizontally along head structure H, and radially or laterally relative to each other, by loosening the T-bolts 33 of a unit, and then sliding the unit the required distance to the right or to the left to its desired position of adjustment on structure l2.

A motorized spindle unit S is mounted in a head H in vertically disposed position extending through and slidably received in the vertical bore 30 of the head and with the operating nose end 22 of the motorized spindle assembly 2| projected downwardly a distance below the head. A spindle unit S is maintained in mounted position in the head H against rotational movements relative thereto by a positioning pin 34 which is secured extending through the lower forward or front portion of head H into and disposed radially of a spindle unit mounting bore 30. Each spindle unit S is provided in the for ward side of its case 20 with a vertically disposed slot 24 into which the inner projected end of the positioning pin 34 of the head H is slidably. received. The positioning slot 24 of each spindle unit opens at its lower end through the lower end of casing 20 to permit of lifting a unit S vertically upwardly to remove the unit from a mounting head.

Vertical bores 35 are formed in each mounting head H opening through the upper side edge thereof and extending a distance downwardly into the head. These vertical bores 35 are located in diametrically opposite positions in a head H between the base 3| and the forward side of the head. A coiled expansion spring 36 is positioned in each of the bores 35. Plunger forming rods 31 are mounted in bores 35 and at their upper ends are engaged by the end cap 28 of the unit. Rods 31 are formed at their lower ends to provide the heads 31a of an external diameter to be received in and form a free fit with the bores 35 of the heads H for vertical reciprocation thereof in bores 35.

In mounted position of a spindle unit S in the bore 36 of a head H, the rods 31 extend downwardly into head bores 35, respectively, with the heads 31a thereof engaged with the upper ends of spring 35 and with these springs confined under compression between the lower end walls of bores 35 and the plunger heads 31a, so that, the rods are spring biased upwardly in engagement with cap 23. By this arrangement there is provided an anti-backlash means for the spindle unit feeding mechanism, as will be referred to hereinafter.

The casing 28 of each motorized spindle unit S is provided with or has machined therein, vertically disposed rack teeth 38 in the rear side thereof disposed in the vertical plan of the diameter which passes through the positioning slot 24 in the forward side of the casing.

Spindle unit feed mechanisms Each head H mounts in a gear train consisting meshed gears 40 and 4|. Referring to Fig. 17, the gear 4| is located in a bore 4|a in base 3|, which bore is horizontally disposed transversely relative to the base. Bore 4|a opens through one side of the base 3|, and a circular block or plug 42 is threaded into the open end of the bore. Plug 42 has an axial bore which slidably and rotatably mounts and receives therein one end of a shaft 43 on which gear 4| is fixed for rotation with the shaft. The opposite end of shaft 43 extends through and is slidably and rotatably received in a bore in the opposite side of base 3|, and projects outwardly a distance therebeyond to provide a push button or plunger 43a. A coiled expansion spring 44 is mounted on and around shaft 43 under compression between block 42 and the adjacent side of gear 4|. Thus, gear 4| is spring biased inwardly and normally maintained in position in mesh at its forward side with the rack teeth 38 of spindle unit S mounted in the head H, and at its rear side with the gear 4|.

By the foregoing arrangement, a motorized spindle unit S may be readily mounted in and removed from a head H by pressing inwardly on the push button end 43a of shaft 43 to thereby displace that shaft and the gear 4| outwardly from its position between and in mesh with gear 40 and rack teeth 38 of the spindle unit, to a position out of mesh therewith. With gear 4| in displaced, disengaged position clear of spindle unit rack teeth 33, a cutter spindle unit S may then be readily inserted in or removed from a mounting head H.

the flangedbase thereof of a pair of normally Gear til is rotatably ounted on a shaft 45 which is mounted in the inner, flanged portion of base 3| of a head H, in horizontal position parallel with shaft 43a. The gear 40 is rotatably received in a vertically disposed slot or passage 40a formed through the inner flanged portion of base 3|. Passage 35a opens at its forward side into bore Ma and at its rear side into the channel In in the forward side of head mounting structure i2. Gear 55 has a diameter such that it projects a distance inwardly into the channel |2a when the head H in which it is mounted, is attached in mounted position on structure I2, as will be clear by reference to Figs. 17 and 18.

A long gear 55 in the form of a toothed shaft or spindle, is mounted in horizontal position extending longitudinally through channel |2a of structure it, and is journaled at its opposite ends in end walls at the opposite ends, respectively, of the channel. This long gear 45 is formed, in this example, with longitudinally disposed teeth forming ribs or splines 46a therearound which extend throughout the length of the gear within the channel |2a. Shaft gear 46 is mounted in position with its axis in the horizontal plane passing through the axes of gears 55 and 5|, for meshing engagement by the inner side of a gear 45 in mounted position of a spindle unit head H on structure I2.

With the multiple spindle heads H in mounted adjusted position on and along the seating surfaces l2b, each of the gears 40 of a head carried feed gear train is thus engaged in driven connection at its inner side with the long shaft gear 45, so that, rotation of gear 45 Will effect rotation simultaneously of the head mounted feed gear trains. With cutter spindle units S mounted in the heads H with the rack teeth 38 of such units in mesh with the inner gears 5| of the feed gear trains, rotation of shaft gear 45 in a clockwise direction will rotate gears 4| of the feed gear trains in a clockwise direction to feed the cutter spindle units S downwardly to operative, working positions, while rotation of shaft gear 46 in a counterclockwise direction will effect feed of the spindle units .3 upwardly to raised, non-working positions.

The arrangement of the spindle unit carried rods 35 and head mounted springs 35, is such as to function to eliminate backlash in the feed gear trains and shaft gear 56, and thus insure precise synchronization of the feeding movements imparted simultaneously to the spindle units S by rotation of the shaft gear 45. With the shaft gear 45 toothed throughout the length thereof within channel |2a by the unbroken, parallel teeth Mia, any mounting head H may be individually adjusted in either direction horizontally along the mounting seats I21) of structure l2, with the inner gear 55 of the feed gear train merely sliding along shaft gear 45 in continuous mesh therewith. Such an adjustment of a head may be effected independently of the other heads H, and without disconnecting the driving connection between the gear 40 of the adjusted head and the shaft gear 46, so that in any adjusted position laterally of a head H the feed gear train thereof will be automatically maintained in driving connection with shaft gear 46.

In the machine of the example, four (4) mounting heads H are shown, but the width of head mounting structure may be considered to be such as to present seating surfaces |2b of a length to accommodate and mount six (6) of the heads H. Obviously anylessernumber of the heads H may be employed if desired, and spindle unit mounting heads of smaller width dimensions than those of heads H of this example, may be utilized, so that, a greater number of heads may be mounted on the seating surfaces 222 of structure l2. Conversely heads of greater dimensions may be employed, so that the maximum mounting capacity of structure |2 will be reduced. Or a greater width may be provided for mounting structure It to form head seating surfaces of greater length to accommodate a greater number of heads H.

Spindle unit feed actuating means The shaft gear :35 which drives the feed gear trains lu-4| of each spindle unit mounting head H, is rotated in either direction by the pneumatic cylinder and piston E. Referring to Fig. 16, this unit E is mounted at the left hand side of head mounting structure l2, being suitably enclosed or encased, and comprises an air cylinder 50 dis posed in a forwardly, upwardly inclined position and mounting therein a piston 5| with a piston rod 52 extending outwardly therefrom through the forward head 55 of the cylinder.

The outer, forward end of the piston rod 52 is pivotally coupled by a link 52a to the upper end of a crank arm 53 which is attached to and extends upwardly from the outwardly extended, adjacent exterior end of the shaft gear 46. The coupling linkage of piston 52 to shaft gear crank 53 is such, that with piston '52 at the end of its rearward, downward stroke, shaft gear 45 is rotated counter-clockwise to position with spindle units S in heads H fed upwardly to raised, nonworking positions, while with piston 5| at its limit of forward, upward movement, shaft gear 45 is rotated in a clockwise direction to feed the cutter spindle units downwardly to operative, working positions.

The inner, lower end of cylinder 50 is closed by a head 54. Head 54 is provided with an air intake-exhaust passage 51 therethrough, opening at its inner end into cylinder 5| and at its outer end opening through the peripheral side wall of head 54 where it is connected with an air supplyexhaust line 58.

A collar 59 is secured on rod 52 adjacent the forward upper end thereof. This collar '59 provides at the inner side thereof an annular abutment surface 59a therearound which is precisely machined or formed to fit and engage against a complementary abutment surface 551) formed at the outer side of the upper end cylinder head 56. Surface 56b thus forms an accurate and precisely located abutment stop for engagement by surface 59a of collar 59 to limit the inward stroke of pis ton 5| to thereby determine accurately the maximum raised positions of spindle units S. v

A coiled expansion spring 55 is mounted on and around piston rod 52 between piston 5| and the inner side of the outer end cylinder head '56. Spring 55 acts to continuously bias piston 5| and rod 52 rearwardly and downwardly in cylinder 50 to its limit position with abutment surface 55a of collar 59 engaged against stop surface 56b of head 55.

Forward, upward movement of piston 5| is effected by admitting air under pressure into the lower end of cylinder 50 through passage '51, to develop pressures acting on piston 5| of a magnitude to overcome the biasing forces of spring 55 to thereby force piston 5 and rod52 upwardly to effect feed downwardly of the spindle units S to operative, working positions. The inner side of cylinder head 56 provides an accurately formed abutment surface 56a. for engagement by a complementary surfacev Bib. formed on and around the adjacent side of piston 5|, an abutment stop for accurately limiting forward movement of the piston and downward feed thereby of the spindle units S in the head H. These abutment or stop surfaces 511) and 56a are accurately located and positioned to give the cutter spindle units S a precise, predetermined maximum lowered or depth position.

It is to be noted that in Fig. 16 the cylinder and piston unit E is shown in air pressure actuated position with the cutter spindle units S fed downwardly and being maintained by air pressure in cylinder 58 in lowered, working positions for engaging cutter tools in the spindles 22, with work pieces W on the work holding and indexing mechanism B. When it is desired to feed the spindle units S upwardly to raised positions, the air supply through supply line 58 is cut oh and the line is then opened to atmosphere for. release of pressure in and exhaust of air from cylinder 50, under the action of biasing spring 55, which then acts to force piston rearwardly to rotate shaft gear 46 in a direction to raise the cutter spindle units S through the operation of the feed mechanism.

Each of the cutter spindle units S is a selfcontained, motor driven unit and each in mounted operative position in its head H is supplied with electrical current by a flexible conductor cable L. These individual circuit cables L to the spindle units S, are each detachable from electrical connection with the motor of its unit and from the unit, when it is desired to remove a unit from a mounting head H. The cables L extend to a switch panel LS which mounts a series of four (4) switches, SI, S2, S3 and S4, for selectively opening and closing the supply circuits through the cables L to the units S, respectively. Thus, the motorized spindle units S may be individually, selectively operated or cut off by the operator from the switches on the switch panel LS. In this instance this panel, with the switch actuating levers of the switches, is mounted on the right hand side of the head mounting structure [2, with. the switch operating levers in position accessible at the exterior thereof, as will be clear by reference to Fig. 3. The switches of switch panel LS are connected with a suitable source of electrical current (not shown) in the usual manner for supplying current through cables L to the motors of the spindle units S.

The sensitive work table unit The work table unit T which is mounted directly on and is vertically adjustable as a unit with the knee K, is of the sensitive or socalled duplicator table type and provides at its upper side the movable work piece supporting and translating table component 80 mounted for universal lateral movements in a horizontal plane. Referring now to Figs. 11 through 15, in connection with Figs. 1 and 4, the table unit T includes a base plate 61 which is directly mounted on knee K for adjustment thereon in the transverse or in and out direction relative to the machine, bythe dovetail slide M on knee K, which is slidably received in the dovetail groove [4a at the under side of base plate 6!.

The base plate 6| is provided along and adjacent each opposite, transverse side edge. thereof with a series of upstanding lugs, which in this to thus providev aeeaese instance include a forward lug 62, an intermediate lug 63, and a rear lug 64, as will be clear by reference to Fig..11. The

lugs

62, 63 and 64 of each series, are spaced and aligned transversely of base 6! and are provided with transversely disposed, axially aligned horizontal bores therethrough. A rod member 65 is secured extending through the bores of the aligned lugs at the left hand end of base 6| with the opposite ends of the rod secured in the forward and

rear lugs

82 and 64,, respectively, and with the intermediate portion of the rod extending through and intermediately supported by the lug 63. An identical rod member 66 is similarly mounted and secured inthe series of base lugs 62, 63 and G5 at the right hand end of the base plate 6!. Thus there is provided at opposite ends of base 6| the

rods

65 and 65 which are disposed horizontally in parallelism with their axes in the same horizontal plane and extending transversely of base plate 6! to. define straight line paths.

A carriage or cradle ll! of generally rectangular plan form is provided having longitudinal and transverse dimensions such that the cradle may be supported in position between rods 65 and 66 for limited movements in either direction transversely thereon above base plate 6| in directions in or out relative to' the machine. At its opposite ends cradle 10 includes the upstanding flanges H forming vertical end walls from the outer side of which extend the spaced arms 12 providing at their forward lower ends the antifriction bearing mounting bolsters 13. Each pair of bearing bolsters I3 is formed with axially aligned, horizontally disposed bores therethrough.

The bearing bolsters 13 at the left hand end of cradle Til mount therein the linear, annular form antifriction bearing assemblies 653 which are mounted on. and slidably receive therethrough the rods 65 at the. left hand end of base plate 61 with the forward bearing bolster I3 and its contained linear bearing positioned intermediate rod supporting lugs 62 and 13 and with the rear bearing bolster 13 and its contained linear hearing mounted on the rod 65 between the intermediate rod supporting lug 63 and the rear lug B4. The spaced bearing bolsters '53 at the right hand end, of cradle 10 mount therein the linear, annular form antifriction bearing assemblies 663 which are mounted on and slidably receive therethrough the rod. 66 at the left hand end of base plate El, with the forward bearing bolster l3 and its linear bearing positioned between the forward and intermediate

rod supporting lugs

62 and 63, and. with the rear bolster 13 and its linear bearing mounted on the rod 65 between the intermediate and rear rod supporting lugs 63. and 54.

By the foregoing mounting and arrangement, the cradle 10 is mounted. and supported at its opposite ends in a horizontal position from the spaced parallel rods. 65 and. 66, constrained or limited to straight. line movements on the rods transversely across base MI, in directions in" and out. relative to the. machine. The linear bearing assemblies. 653 and BBBv provide minimum friction. slidable mountings. for the cradle 10 on rods 65 and 66, so that, the cradle is highly sensitive and responsive to. movement by the application thereto of forces of relatively small magnitudes.v

Adjacent the rear, longitudinal side of cradle 10 there is mounted, extending. between the opposite, upstanding. flanges H... a rod. member 14. Rod 14 is secured at its opposite ends in aligned bores 14a in opposite end flanges 1| with the rod in horizontal position with its axis perpendicular to the axes of the parallel, transversely disposed rods 64 and 66. The rod end receiving bores 1 3a are located at the rear sides of and opposite bearing bolster supporting arms 12, respectively, and these bores may be extended outwardly through arms 12 for ready assembly and removal of rod 1 1 to and from mounted position. Suitable set screws 1401 may be employed for securing the rod ends in flanges H.

A rod member 15 identical with rod 14, is mounted in position along and adjacent the forward longitudinal side of cradle 16 in horizontal position parallel with the rearwardly mounted rod 14. Rod 15 is secured in mounted position with its opposite ends received in bores 15a of flanges 1! by set screws 15:2. The bores 15a may be extended outwardly through the adjacent arm 12, respectively, to permit of ready assembly and removal of the rod. The cradle 16 may be provided with upstanding lugs 16 intermediate the opposite end flanges 1| for receiving therethrough and providing intermediate support to the forward and

rear rods

14 and 15, respectively.

The work piece mounting and translating table component of member 80 of the table unit T, is slidably mounted on the

parallel rods

14 and 15 and is constrained by these rods to straight line movements in opposite directions in directions longitudinally of the machine and perpendicular to the path of in and out, transverse movements of cradle on the rods 65 and 66.

The table 80 is provided with spaced lugs 8! depending therefrom adjacent the rear longitudinal side thereof with each of these lugs mounting therein a linear, annular type antifriction bearing assembly 14B. These bearing assemblies are mounted on and slidably receive therethrough the rod 14 with lug 8i and its bearing 14B located between the left end flange II and intermediate supporting lug 16, and the other lug 8i and its bearing 14B positioned on rod 14 between the right hand end flange 1| and the intermediate rod supporting lug 16.

A pair of depending, spaced lugs 82, identical with lugs 8|, are provided at the under side of table 80 adjacent the forward longitudinal side thereof. Each of these lugs 82 mounts therein a linear, annular type anti-friction hearing assembly 153, with these bearing assemblies mounted on and slidably receiving therethrough the forwardly located rod of cradle 10. One lug 82 with its linear bearing 15B is positioned on rod 15 intermediate the left hand end flange 1| of the cradle 10 and the intermediate supporting lug 16, while the other lug 82 and its linear bearing 15B are located on rod 15 intermediate the right hand end of flange H and the intermediate supporting lug 16.

Each of the bearing

assemblies

65B, 65B, 14B and 15B is identical and in this example, is comprised by a known commercial type of linear, annular or sleeve form of antifriction bearing assembly. The construction of the example bearing assembly is illustrated in Fig. 13, and comprises a sleeve 11 within which there is con centrically mounted and confined a tubular retainer 18 which receives and through which a rod or shaft is mounted. The retainer 18 is provided with and mounts a plurality of oblong circuits of antifriction balls 19. Each of the ball circuits 19 presents two (2) straight sides,

with one straight side 1911 in bearing contact between an inner surface of the ball bushing 14 sleeve and the rod or spindle extending through the assembly. The antlfriction balls in the remainder of each circuit are free to roll unloaded, in clearance provided in the sleeve.

The horizontally positioned work piece mounting table component or member 86 of table unit T is thus movable transversely with the cradle 10 as a unit, in and out relative to the machine on and with the table 86 and cradle 16, constrained to straight line paths by the spaced, parallel rods 65 and 66. Table 86 is also movable on and independently of cradle 10 in either direction longitudinally of the machine, on and constrained to straight line paths by the spaced,

parallel rods

14 and 15 which are positioned with their axes perpendicular to the straight line paths of transverse movements of the table and cradle 10 on rods 65 and 66. And, by simultaneous compound movements of the table 80 and of the cradle 10 along the pairs of rods 6566 and 14-15, respectively, the table is thereby universally laterally movable on base 6! in one plane, in this instance, a horizontal plane.

The table 80 is provided with the usual T- slots 80a in the upper side thereof extending longitudinally across the table for the purpose of mounting on the table, work pieces or work piece holding fixtures.

Due to the mounting of the cradle 10 and the table 80 by means of the linear,

antifriction bearing assemblies

65B, 66B, 14B and 15B slidably mounted on the respective supporting track forming rods 6566 and 14-15, the table 80 is rendered extremely sensitive and highly responsive to table moving forces and to the directions of such forces, applied to the table. The construction and mounting of the base 6|, cradle 10 and the table 80, together with the mounting arrangement of the base carried rods 65 and 66 and the cradle carried

rods

14 and 15, together with the use of commercially available types of linear, antifriction bearing assemblies, make it possible to construct and to assemble such table units at relatively low manufacturing costs by eliminating the necessity for manufacturing specially designed and constructed antifriction bearing slide arrangements for the table unit components, while at the same time providing a construction and assembly which is precise and highly sensitive under production conditions of operation and use, with long wear and with maintenance reduced to a minimum.

The table unit itself, together with the combination thereof with the supporting or knee structure K, by which the table unit T is directly mounted on the knee, provides compactness in the direction transversely of the unit, in this instance in the vertical dimension, so that a machine with which the unit and its supporting structure are used, has an increased capacity for mounting a wider range of sizes of work pieces.

A table unit T of the invention is in no sense limited or restricted to adaptation and use with the machine of this example, or to the combinations in which it is found in this example machine. Table units of the invention are intended for and are adapted in the form here shown, or in various modifications thereof, to general use as a universally, laterally, movable sensitive type of work table.

No claim to the sensitive work table unit per 'se,

except as a'component in the combinations in claims hereof, is made herein, as such sensitive work table unit and the construction and comfined on slide bar 92 in blnations of elements thereof, is disclosed and claimed in my copendingfU- S. patent application SerialNo. 359,581, filed as. a division of this application.

The pantograph and sensitive table combination The pantograph mechanism P is of the parallelogram linkage type, and is suspended from a fixed pivot supported from the machine frame structure at the righthand side of the machine, with the pantograph positioned in a horizontal plane parallel with the plane of the universally laterally movable, sensitive work table 80. The pantograph mechanism P so positioned is operatively coupled with the right hand end of table T for translating and transmitting to the table 89 in sealed reduction, the movements of the pantograph controlling. tracer A as this tracer scans the pattern on the master unit M.

Referring to Figs. through. 10, in connection with Figs. 1 2 and 3, the pantograph mechanism P comprises the spaced, parallel, inner slide bar 99 and outer bar 9i, and the spaced, parallel forward and

rear links

92 and 93, pivotally coupling and connecting bars 90 and 9! to form the parallelogram linkage in the usual manner. The forward link 92 constitutes a slide bar, while the outer bar 9| is forwardly extended to constitute a tracer arm 94 which mounts at its forward end the tracer unit A.

The pantograph P is pivotally supported and hung from a vertically disposed pivot pin or stud 95 which is carried in and depends from the outer end of a forwardly and outwardly extended hanger arm 96 of a bracket structure 91 which is supported on the horizontally disposed upper side surface of the mounting base l9, by which the master wheel mounting arm 15 is attached to the right hand side of the frame structure of the machine. Base I6 is provided with a T- slot "5a in the upper horizontal surface thereof which is disposed transversely of the machine. Pantograph mounting bracket structure 91 is adjustably secured in position on base l6 by a T-bolt 91a attached in slot id, to permit of adjustment of the bracket structure with the pantograph P hung therefrom, in either direction transversely relative to the machine.

The vertical pivot stud 95- is journaled in an anti-friction bearing assembly 95a (see Fig. 7) in the bracket arm 96, and this stud mounts at its lower end the slide block 98 within which the slide bar 96 of the pantograph is adjustably secured. Thus, the pantograph mechanism P as a unit, may be adjusted relative to pivot stud 95 to thus adjust the position of the axis of that stud longitudinally of bar 99.

The forward link of slide bar 92 is positioned below bars 90 and 9!, and the forward end of bar 99 mounts a fixed pivot pin 90a which depends therefrom and which is journaled in an antifriction bearing assembly 992) mounted in bar 92, for relative pivoting or rotation of

bars

99 and 92, as will be clear by reference to Fig. 7. A slide block 99 is slidably mounted and conposition at the underside of that bar and being slidable longitudinally in either direction therealong. I

The rear link 93 of the pantograph mechanism P is positioned below end of link 93 is pivotally coupled to the rear end of link 99 by a pivot pin 99c fixed in and depending from bar 99 and journaled in an antiiriction bearing; assembly 9311 mounted in link 93,

bars 90 and 9!. The inner.

=aswill be clear; by reference to. Fig. 8. The outer end of'link 90 ispivotally coupled to the rear end of outer bar 9| by a pivot pin 91afixed. in and depending frombar9l andv journaled in an antifriction bearing assembly 93b mounted in the outer end of link 93, as shown in Fig. 9. The outer end of forward link or slide 92 is pivotally coupled to bar 91 by a pivot stud 9lb fixed in and depending from bar 9| and journaled in an antifriction bearing assembly 92a mounted in the outer end of link or slide bar 92, as shown in Fig. 10.

The pantograph mechanism P is thus adjustable in the usual manner to vary the ratio of scaled reduction of the movements transmitted to the mechanism by the tracer arm 94, by adjusting the

bars

90 and 92 in the slide blocks 98 and 99, respectively, to relatively position the axes of pivot pins 95 and 9011 along and relative to the longitudinal axes of

bars

99 and 92, respectively. In the example hereof, movement in scaled reduction of the movements of the tractor T at the outer end of tracer arm 94, are taken off from the pantograph mechanism at the slide block 99 which adjustably, slidably receives pantograph bar 92.

The slide block 99 is coupled with the universally laterally movable sensitive table 89 by means of a coupling mechanism which permits of vertical adjustment upwardly and downwardly of table with table unit T and knee K as the unit, without displacing or moving pantograph mechanism P from the horizontal plane in which it is hung and supported by the hanger bracket 96. In the particular adaptation of such a coupling mechanism for the example machine, referring now to Fig. 7 in particular, in connection with Figs. 2 and 5, the slide block 99 mounts therein an annular antifriction bearing assembly 99a of the double bearing type, with the axis of the assembly vertically disposed. A sleeve member 99b is mounted and journaled in its upper end in bearing assembly 99a and depends vertically downwardly therefrom a distance below slider block 99. A headed stud 990 is mounted and received in sleeve member 9912 and extends downwardly therethrough to provide an externally threaded lower end on which there is mounted a fastening nut 99d to engage and secure the stud and sleeve together as a unit assembly journaled in bearing 99a.

An outwardly extended, horizontally disposed rod member 83 is clamped at its rear end on the sleeve in stud assembly 99b-99c, with its axis parallel with the transverse axis of the machine. The forward end length rod member 93 is formed of a reduced external diameter. A link member 84 is pivotally mounted on the reduced diameter portion of rod member 83, and a coiled expansion spring 85 is mounted on member 83 between the shoulder 83a formed at the inner end of the reduced diameter portion and the inner side of link 84.

The outer end of the reduced diameter portion of rod 83 is provided with external screw threading 83b thereon (see Fig. 5), and a micrometer barrel 83 is threaded onto rod 99 and provides a reduced diameter scale bearing hub portion 86a at the inner side thereof for engagement by the adjacent forward side of link 84. A micrometer scale 86s is provided on and around hub portion 8911 with an index line 86b being provided on the upper side of link 34 for selective alignment by rotation of barrel 86 with the micrometer divisions of scale 98s. A lock nut 890 is also threaded on red 83 at the outer side of micrometer barrel 86, for releasably looking barrel 86 in an adjusted position. The spring 85 continuously biases link 84 outwardly on rod 83 into adjusted position engaged against microrneter barrel hub 86a. The position of link 84 axially on rod 83 is thus adjustable by adjusting the position of the micrometer barrel 86 inwardly or outwardly on the rod 83.

The inner end of link member 84 is provided with a forwardly extended crank pin or shaft member 87 which is disposed radially relative thereto and which extends forwardly and horizontally therefrom. Shaft 8? is accurately formed and positioned so that its axis is in substantially precise parallelism with the axis of rod member 83 on which the outer end of link member 84 is rotatably mounted.

The right hand end wall of table as has the horizontally disposed T-slot 80b therein opening outwardly therethrough, and a bearing block member 83 is adjustably secured in the T-slot 80b in position attached to table 80 for movement therewith as a unit. This bearing block 88 provides a horizontally disposed bearing 88a therein which receives and in which shaft 81 of the coupling link member 84 is journaled for pivoting. Thus table 8-9 is coupled with the slide block 99 of pantograph mechanism P and is universally laterally movable by universal lateral movements of the slide block by the panto'graph mechanism under the control of the tracer T at the forward end of pantograph tracer arm 94. The position of coupling link member 84 relative to slide block 99 and pantograph mechanism P, along the axis of rod member 83 is adjustable by the micrometer adjusting mechanism which includes the micrometer barrel 86.

By the foregoing coupling arrangement, the table 88 may be vertically adjusted upwardly or downwardly without interfering with or changing the position or level at which pantograph mechanism P is hung and supported. On upward or downward adjustment of table 88, the coupling link 84 merely pivots or swings about the horizontal, parallel axes provided by rod member 33 and the shaft or pin 81 which is journaled in the bearing block 88 carried by table 89.

The table unit Tis also capable of adjustment transversely and/or longitudinally with the knee as a unit on the knee slide I4 and on the column slide ifib, while the pantograph mechanism P is adjustable transversely of the machine by a"- justing the supporting bracket 9% on base member 55.

The combination of the universally laterally movable table with its minimum friction mounting comprised of the rods and linear antifriction ball type bearing assemblies, together with the pantograph mechanism P with its antifriction bearing pivots, substantially eliminates all looseness and play to thus insure precision reproduction with minimum inertia and highly sensitive responses as precise movements in sealed reduction by the table 30, to movements of the pantograph mounted tracer'on the pantographcontrolling tracer arm 94.

Tracer and indemable master units Referring to Fig. 19, the tracer unit A embodies a tracer stem I Elli which is slidably mounted in a vertically disposed tubular hub or sleeve member I GI formed, in this instance, integral with tracer arm as at the outer end thereof. Tracer stem Ilia has a plunger head I02 at the upper end thereof forming an operating'button thereupper end of stem I09 under compression between a shoulder provided by housing I DI and the under side of button I02, so that, the tracer stem is normally biased to raised position out of tracing or scanning engagement with a pattern on the master wheel M therebelow. At its lower end tracer stem Hid removably mounts a stylus I8 3 depending therefrom for tracing engagement with a pattern on master wheel M, when the tracer stem is depressed. Tracer stem I90 also mounts at its lower end a cap member providing an upwardly extending annular flange I therearound which slidably extends up over and around the exterior of housing IOI and provides a camming surface for a purpose to be hereinafter described. I

The indexable master unit is constituted by a master wheel M having a laterally forwardly projected annular flange III] therearound providing a peripheral surface III for receiving and removably mounting thereon a series of patterns IIZ (see Fig. 1). These patterns i I2, in the present example, are individually removable and replaceable on the surface III, which surface may be suitably formed to provide seats or bases spaced therearound for mounting the patterns. The master wheel M, referring now to Fig. 19 in connection with Fig. 5, is rotatably mounted in vertically disposed position at the forward side of arm structure I5 for rotation about a horizontal axis disposed transversely of the machine, in position with the highest portion of the upper side of rim IIO located directly below the tracer unit A at the outer end of tracer arm 94. The rotatable mounting for pattern wheel M embodies, a spindle II l journaled in antifriction bearing assemblies Ilsa carried in a hub portion l5a at the forward end of arm structure I5. 'The hub portion IIiiA of master wheel M is secured to the forward end of spindle H4 by a suitable securing bolt or the like member Illlb. A circular shield is mounted on the hub I5a and provides a forwardly extended flange Ilia spaced outwardly from and around and concentric with the pattern mounting flange III) of wheel M, with this flange IISa cut away at the upper side thereof to form a tracing station at which a selected pattern H2 is positioned and exposed for tracing engagement by tracing style Hi l of the tracing unit A. In the instant example, pattern wheel M is manually rotatable in either direction to position a selected pattern H2 at the tracing station at the upper high side of the wheelM.

An indexing mechanism is provided for re' leasably locking master wheel M in position with a selected pattern at the tracing station. The master wheel M at the rear side thereof is provided with a spaced series of indexing notches N therearound extending radially inwardly from the periphery of the wheel (see Figs. 2, 5 and 19), with each of the notches N lying in a radial plane which passes through the center of a pattern mounting base on the surface II I of wheel M. A supporting housing structure II 6 is se cured at the upper side of hub I5a of arm structure I5 on the rear of shield I I5 and this housing structure mounts a horizontally disposed casing I I! within which there is slidably mounted an indexing plunger H8. Plunger II8 projects forwardly from casing H I in position for engaging and seating at its forward end into an indexing notch N of wheel M. Indexing plunger 8 is spring biased by a spring I I Ba to forwardly projected. indexnotch engaging position.

A coil spring m3 is mounted around the r