US2347558A - Drawing machine or layout table - Google Patents

Description

April 25, 1944. o. c; HEDIN 2,347,558

DRAWING MACHINE OR LAY-OUT TABLE Filed Sept. 21, 1942 5 Sheets-Sheet 1 INVEN TOR.

as? C flea/N Ap 25, 1944- o. c. HEDIN 2,347,558

DRAWING MACHINE OR LAY-OUT TABLE Filed Sept. 21, 1942 5 Sheets-Sheet 2 IN V EN TOR.

MWM

April 1944- o. c. HEDlN 2,347,558

' DRAWING MACHINE on LAY-OUT TABLE Filed Sept. 21, 1942 5 Sheets-Sheet 4 April 1944- o. c. HEDIN 2,347,558;

97 Q0 INVENTOR. I

k 15 BY Oscne C. H501 WQW Patented Apr. 25, 1944 A Oscar C. Hedin, Cleveland Heights, Ohio, assign- I or to The Weldon Tool Company, Cleveland, 7 Ohio, a corporation of Ohio Application September 21, 1942, Serial No. 459,102

28 Claims.

This invention relates to a drawing machine or lay-out table by which drawings requiring extreme accuracy can be made. By way of example, it might be stated that the invention is useful in producing large scale drawings of tools or the like which are to be ground or machined and which drawings can be applied to the screen of an optical inspection system and on which screen a shadow of the tool being ground or checked is projected for comparison with the drawing. The invention may be briefly summarized as consisting of certain novel features of construction and combinations and arrangements of parts which will be described in the specification. and set forth in the appended claims.

In the accompanying sheets of drawings showing a preferred embodiment of the invention,

Fig. l is a front elevation of the machine;

Fig. 2 is a top plan view of the same;

Fig. 3 is an enlarged perspective sectional view illustrating one of the scales of the machine with its saddle and associated slide, this section being taken substantially on the line 3-3 of Fig. 2;

Fig. 4 is an enlarged perspective sectional view showing another scale together with the saddle, slide and scriber associated therewith, this section being taken substantially on the line 4-4 of Fig. 2;

Fig. 4a is an enlarged detached perspective view of the slide which carries the scriber, the slide being shown in section;

Fig. 4b is a view on an enlarged scale of the end of the scriber or stylus; I

Fig. 5 is another enlarged perspective sectional view of the first scale taken substantially on the line 55 of Fig. 2;

Fig. 6 is an enlarged perspective view taken as "indicated by line 6-6 of Fig. 2 and showing a portion of the circular rotatable table with its annular scale and "the vernier associated therewith;

Fig. 7 is a view on-an enlarged scale taken as indicated by line 1- 'I of Fig. 2 and showing a clamp provided on the carriage for cooperation with the slide which is movable along the second Fig. 11 is an elevation of a microscope which is used interchangeably in place of the scriber assembly to accurately locate desired points on the drawing;

Fig. 12 is a partial 'plan view on an enlarged scale showing a trammel device applied to the slide of the firstscale; and

' Fig. 13 is a partial sectional view taken substantially On line l3-"l3 of Fig. 12 to further illustrate the trammel device.

Referring now to the drawings in greater detail, I0 represents a base with supporting feet II which rest on the floor. Secured to the top of the base "I is a spider I: which, as best shown in Fig. 2, comprises four laterally projecting arms Hi, the ends of which are turned outwardly toward opposite sides of the machine, as shown at l3a in Fig. 2. Braces l4 connect opposite pairs of arms I3 to provide a rigid supporting structure. To the outer bent ends of the spider arms l3 are secured two parallel rails I 5 to one of which is'secured a long way l6 which extends practical- 1y the full length of its rail and to the other of the rails is secured a shorter way I1.

A rotatable circular table It is located between the spaced ways l6 and I1, and, as will be described in greater detail hereinafter, is adapted to support the paper, plate or the like on which the drawing is to be made. The table has a depending central sleeve portion l9 surrounding a spindle 20 which projects upwardly from the base In above the spider I2. The table is rotatably supported by bearings 2| interposed between the sleeve and spindle.

The ways I 6 and I! have inverted V-shaped top portions or ridges supporting a carriage 22 for movement forwardly and backwardly over the table IS. The carriage is slidable on the ways and is supported thereon by a pair of bronze shoes lBa engaging the long way l6 and a single bronze shoe Ila (see also Fig. 10) engaging the shorter way l1. As shownin Fig. 2, the left end of the carriage is of a triangular construction for maximum rigidity, this being obtained by providing a rigid connecting bar 22a which extends in an acute angular relation between the left end of the bar portion 22b of the carriage and the body portion 220 thereof.

As shown in Fig. 2, mydrafting-machine is provided with two straight or lineal scales 23 and 24 which are calibrated in inches and are arranged to extend at right angles to each other. The scale 23 is located on the body portion 220 of the carriage and is movable therewith over the table It. The scale 24 extends along the shorter way I! and is fixed or stationary.

For mounting the scale 23 on the body portion 22c of the carriage, I'provide the latter with a saddle 25 having a longitudinal groove 26 in which this scale is fixed (see Fig. 4). The sides of the saddle project laterally as longitudinally extending flanges having V-shaped edges .21. The scale 24 is similarly mounted on the front rail l by providing the latter with a saddle 28 having a groove 23in which this scale is fixed (see Figs. 3 and .The sides of the saddle 28 also project laterally as longitudinally extending flanges having V-shaped edges 36.

For making use of the scale 23, I provide the same with a slide 3| which is movable therealong and which carries a vernier 32 in a position to cooperate with the scale. The slide 3| also carries a scriber assembly 33 which will be presently described and which includes a scriber 34 (see Fig. 4) for engagement with the paper or plate during movement of the slide along the scale 23. The extent of movement which the' slide 3| is permitted along the scale 23, and hence the length of line to be drawn by the scriber 34, is determined by two stops 35 and 36 which are movable along.the saddle 25 and are adapted to be clamped at the desired setting by the screws 31. The slide 3| and the stops 35 and 36 have grooved sides which slidably engage the V-edges of the saddle 25. The slide 3| also has a clamping screw 33 by which it can be locked to the saddle 25 at a selected point along the scale 23 whenever this may be desirable.

The scriber assembly 33 includes a bushing 39 which fits in, and extends through, an opening 3|a in an arm 3|b of the slide 3|. The scriber body or holder 40 is slidable and rotatable in the bushing and its lower end embodies a chuck 4| which holds the scriber 34. In this instance the scriber is in the form of a stylus, but it should be understood that by a scriber is meant anything by which the drawing may be delineated, such as a pencil, pen or stylus.

The upper end of the bushing 39 is provided with two axially extending slots 42 and 43 which are spaced apart 90 and a relatively shallow slot 44 located between the first two slots. The scriber body 40 carries a radial pin 45 which, when engaged in the shallow slot 44, holds the scriber body in a relatively elevated neutral or inoperative position so that the scriber 34 will not contact the drawing. When the pin is moved into one or the other of the slots 42 and 43, the scriber will rest on the drawing and may be held thereagainst by a suitable weight (not shown) applied to the reduced stem 46 on the upper end r of the scriber body 40. As shown in Fig. 4b, the end of the stylus is in the formof a pointed pyramid, and when the pin 45 engages in one or the other of the slots 42 and 43, the stylus will be so held that one of its flat pyramidal faces 41 is at 90 to the direction of the drawing or scribing stroke so as to produce a clear, sharp line on the drawing.

The bushing 33 of the scriber assembly 33 is provided with a collar 43 which seats against the arm 3lb of the slide 3| for supporting the assuch clamping engagement with the collar by first moving the bar endwise on the headed pin 53 toward the bushing 33 and then lifting the outer end of the bar by means of the thumb screw 54 which extends through a threaded opening of the bar. causes the bar 52 to fulcrum on the pin 53, thereby pressing the forked end-5| against the collar 43. When the scriber assembly is to be removed from the slide 3|, the thumb screw 54 is rotated in the opposite direction to lower the bar sembly in the opening 3|a. The collar 48 may and release the clamping pressure of the forked end. The bar can then be moved endwise on the pin 53 to withdraw the forked end from the bushing 39.

For cooperation with the scale '24, I provide a slide 55, as shown in Figs. 2 and 3, which is movable along the V-edges 30 of the saddle 28 and carries a vernier 56 and a clamping screw. 51 by which the slide can be clamped-to the saddle at the desired setting along the scale. The scale 24 is also provided with a clamp 53 which is movable along the scale and is adapted to be clamped to the saddle 28 by means of the screw 59. The clamp 56 serves as a stop for limiting the movement of the carriage 22 along the ways in the left-hand direction.

When the slide has been properly positioned along the scale 24 by means of the vernier '56 and clamped in place by turning the handle connected to the screw 51, the carriage 22 is moved forwardly (to the right) up to the slide 55 and is locked thereto by a latch 60 which is carried by the adjacent end of the carriage, the latch being normally held in elevated position by a spring 6|. The locking action is obtained in the following manner: The latch 60 has a downturned jaw 66a which the operator will lower into the vernier opening of the slide 55. The operator will then swing the lever 52 which is connected to an eccentric 63 so as to pull the jaw 60a against the inner side of the vernier opening. To release the carriage 22 from the slide 55, the operator will simply reverse the position of the eccentric 63, whereupon the spring 6| will elevate the latch 60. v

It might be stated in passing that a magnifying glass, shown at 64 in Fig. 1, may be employed with either the vernier 32 or the vernier 56, the magnifying glass being removable and so shaped that it can be applied to either the slide 3| or the slide 55.

Reverting to the turntable l3, this member is preferably constructed as a phosphor-bronze plate whose upper face provides a smooth surface on which the sheet material for the drawing (not shown) is secured by pieces of tape or other appropriate means. This sheet material on which the drawing is to be made or delineated may be paper, cloth, an emulsified plate, or even a metal plate. The outer edge of the turntable is provided with a circular scale 65 which is graduated in degrees and extends for the full periphery of the table.

A fixed arcuate vernier 66, preferably readable in minutes, is associated with the graduated edge of the turntable I 8. This vernier is mounted on an extension 51 (see Figs. 2 and 6) which is secured to the front rail l5 at the right-hand end of the stationary scale 24. For use with the vernier 56 and the scale 65 of the turntable, I provide an adjustable radial reference line 68 which enables the turntable to bet set very accurately. This reference line is scribed on a transparent medium 69 which is carried by a holder 10 The lifting action of the screw 54 extension 14 on the holder 18 and bearsagalnst the upper side of a slot 15 provided in the vernier support 81. A screw18- which at its lower end normally bears upon the short plate 13 retains the holder 18 with thereferenc'e line 88 thereon in agiven position. By loosening the screw 18, i the reference line and its hol'der can be moved along the arc-shaped groove H and the arcshaped groove 15.

- After the turntable i8 is adjusted, itis tightly clamped in position, and this is accomplished by the following means: Behind the support 81 for the vernier 88 is pivoted a lever '11 (see particularly Figs. 8 and 9), the rear end of the lever being shown in Fig. 6. At the free end of the lever is a O-shaped floating clamp 18, shown in Figs'. 6, 8, and 9, which is carried by the lever and overlaps the top and bottom of the turntable and extends about its outer edge. On the underside of the top of the clamp is a phosphor-bronze plate I9 which is adapted to be pulled into ongagement with the top surface of the turntable, and on the lower side of the clamp is a clamping block 80 which is adapted tobe simultaneously lifted into engagement with the lower side of the turntable. This clamp is adapted to be actuated by a screw'8i with an upstanding reduced portion 82 (see Fig. 9) which at its upper end is adapted to engage a depending lug 83 of the block 88. In Fig. 8 the clamp 18 is shown in released position, at which time the pin 8| of the clamp is held in engagement with a stop pin 85 projecting from the vernier support 61 by the action of the spring 86 (see Fig. 9) on the lever 11. After the turn table has been adjusted to a given position, the screw BI is turned so as to move the clamp 18 downward with the phosphorbronze plate 19 thereof engaging the top of the turntable and the block 80 simultaneously engaging the lower side of the turntable, thereby locking theturntable against rotation and, incidentally, causing separation of the pins 84 and 85. This clamping action is designed to be positive and at the same time to cause no stress and resultant distortion of the turntable on its bearings.

employ a microscope, such as shown in Fig. 11, to locate points on a drawing. This microscope has a conventional pair of cross lines not shown) which are carried by an ocular disk 88. To use the microscope, the scriber assembly 33 is re-.

moved from the opening 3la of the slide 8i and the microscope 81 isplacedin this opening so that the collar 89 rests on the arm Nb of the slide. The microscope is retained in the opening 3Ia by the clamping action of the bar 52 against the collar 89. Then the carriage 22 and the slide 3| with the microscope thereon can be co-ordinately moved over the drawing until the cross lines on the ocular disk 88 are in optical coincidence with the desired point, such location usually being determined by observation of lines previouslyv on the drawing the vernier 32.

In using my improved drawing machine, straight lines can be scribed on the drawing by moving the slide 3| along the scale 23 after this scale has been appropriately located at the deor by employment of sired point over the table i8. Other straight lines can be drawn at right angles to the first lines either by moving the carriage 22 bodily over the table I! after the slide 8| has been appropriately located on the scale 23 or by first rotating the table through 90 and then moving the slide 8i along the scale 23 after the scale 23 has been located at the desired point over the drawing by movement of the carriage 22. Straight lines extending at angles other than 90 to the first straight .lines can also be drawn by rotating the Under certain circumstances, it is desirable to I table I8 through the necessary angular distance and then moving the slide and scriber assembly 33 along the scale 23. when circles or other arcuate lines are to be scribed on the drawing, this can be accomplished in two ways. One way is to shift the paper or plate on which the drawing is being made to bring the center of the desired arc or circle exactly on the center or rotation axis of the table l8. The carriage 22 and the slide 3! are then appropriately moved to bring the scriber 34 at the desired radial distance from the center of the table, whereupon the table is rotated through the necessary angular distance to cause the desired are or circle to be scribed on the drawing.

The second way of drawing arcs or circles is by the use of a trammel device which is illustrated in Figs. 12 and 13 of the drawings. This trammel device comprises a beam or arm in the form of a saddle a carrying 'a graduated scale 90 and a slide 9i movable along such scale and having a vernier 92 thereon. The slide*9l is similar to the slide 3| in that it includes a clamping screw 93, similar to the. screw 38, by which it can be locked at a desired position along the scale and also has an arm portion 94, corre- .sponding with the arm portion 3ib, and in the opening 95 of which the scriber assembly 33 can be mounted as shown in Fig. 13. The inner end of the saddle 90a carries an arm 96 having thereon 'a pivot pin 91 adapted to be engaged in the opening 3ia of the slide 3i after the scriber assembly 33 (or microscope 81') has been removed from such opening. After the trammel device has been mounted on the slide 3|, the axis of the pivot pin 91 previously having been brought into exact coincidence with the center of the are or circle to be scribed by appropriate mechanically and/or optically controlled movements of the carriage 22 and the slide 3| and the slide 9| having been adjusted to bring the scriber 34 at the proper radial distance from such center, the trammel device is swung about the axis of the pivot pin for the necessary angular distance to scribe the desired are.

To prevent deflection or sagging of the trammel device due to the weight thereof, I may provide this device with an auxiliary support which is engageable with the surface 015 the table Hi. This auxiliary support may comprise a slide 98 which is shiftable along the saddle 98a and has on or more headed stems 99 glidingly engaging the surface of the table. The slide 98 may also b provided with a clampingscrew [00 by which it may be locked to the saddle 99a at a desired point thereof.

For the convenience of the operator, I may on paper, emulsified or metal surfaces, of the most complicated mathematical or geometrical nature, with a flexibility of method and to a degree of accuracy heretofore unattainable with such devices.

The scriber (pen, pencil, or stylus) point and microscope optical axis are common, due to their mechanically accurate interchangeability as to operating position. By means of the sliding membersstraight lines may be generated or drawn. By means ofappropriate scales and verniers the lines may be accurately located in terms of thousandths of an inch. The sliding members in combination with the appropriate scales, verniers and stops permit drawing lines of predetermined lengthand position, truly parallel and spaced to a repeatable accuracy of thousandths of an inch. Employment of the 90- degree co-ordinately sliding members permits lines to be drawn, accurately located and/or spaced, at'right angles one to another. The rotatable table with its 360 graduated circle and associated angular vemier permits the drawing of lines at other various mutual angles, determinable and repeatable in increments of 5 minutes of arc. The rotatable table may be used for the scribing of circular lines about a center common to the axis of rotation of the table. By means of the microscope which, by means of the Vernier slides, may be positioned with its optical axis common to the axis of rotation of the table, predetermined or laid-out locations on the drawing is to be made, a framework, a carriage movable on said framework over the table, said carriage having a scale and a scriber-canying slide movable along said scale, a stationary scale supported by the framework, 9. vemier slide movable relatively to said stationary scale, and means for clamping the carriage to said vernier slide;

4. A drawing machine or lay-out table comprising a base, a table supported by said base and adapted to receive the material on which the drawing is to be made, a framework provided with ways, a carriage movable on said ways over said table, said carriage having a scale, a scriber slide movable along said scale, a stationary scale supported by said framework, a vemier slide movable relative to'said stationary scale, and a the drawing may also be positioned common to the axis of table rotation for the purpose of scribing circular lines about said location points, the radii of said circular lines being accurately attainable by either of the co-ordinate verniers. Additionally, the axis of rotation of the trammel device, because it is common to and interchangeable with the microscope optical axis, may, by employment of the sliding members and verniers, be so located at any desired points on the drawing as to permit the describing of circular lines about said points and of radii attainable by the sliding members and vemier scale of th trammel beam.

Having thus described my invention, I claim:

1. A drawing machine or lay-out table comprising a base, a drawing table supported on said base, a carriage movable on said base over said table, said carriage having an arm having a scale thereon, a sighting slide guided on said arm and overlying said scale and carrying a line-generating medium, a stationary scale supported by the frame and having a sighting slide directly thereover and guided therealong by means on said frame, a part of said carriage being adapted to abut said last mentioned sighting slide, and each slide having means to clamp it at any desired position on its scale.

2. A drawing machine or lay-out table comprising a base, a drawing table rotatably supported by said base, a carriage movable on said base over the table, said carriage having an am having a scale, a sighting slide guided on said arm over said scale and having thereon a scriber disposed close to said arm and scale, a stationary scale supported by the base, and a sighting slide adapted to be clamped relative to said stationary scale and movable therealong, said carriage being adapted to be limited in its movement by said last mentioned slide;

3. A,drawing machine or lay-out table comprising a base, a table supported by said base and adapted to receive the material on which adapted to'be clamped in various positions of adjustment.

6. A drawing machine of the character described comprising a frame, a table on the frame adapted to support the material on which the drawing is to be made, a carriage supported by the frame for movement over said table, a scale mounted on said carriage, a slide movable along the scale on said carriage, and having an opening adapted to receive a scriber and a trammel having a projection releasably pivoted in said opening and carrying a slide also having an opening adapted to receive a scriber, said openings being of the same diameter.

' 7.'A device of the class described, comprising a support having thereon a table, a carriage slidable on the support over the table and having a scale and a tool-carrying slide having a vernier and movable over and along the scale, a stationary scale on the support, a stop-slide having a vemier and movable over and along said stationary scale, each slide having means by which it can be clamped in any adjusted position in reference to the scale, and the support and carriage respectively having means for so guiding its slide as to prevent vertical motion thereof.

8. A device of the class described, comprising a frame slidable on a support, said frame having an arm pointing toward the operators station, a tool holder slidable on said arm in a direction perpendicular to the direction of slidingof the frame and in relation to a scale also on the arm, said holder having means for rigidly but releasably holding a tool, a sighting-slide adjustable along a scale fixed on the support at its front and at the operators station and parallel with the direction of sliding of the frame, said slide having means for clamping it at any adjusted position along said fixed scale, a table on said support below said arm, and means carried by said arm and slide cooperable for releasably locking the arm to the slide.

9. A device of the class described, comprising a frame movable on parallel ways of a support, a combined tool holder and sighting slide slidable on said frame in adirection perpendicular to the ways, and in relation to a scale on'the frame and having an opening adapted to releasably receive a x tool, a sighting slide on said support adjustable along a scale in a direction parallel to one of said ways and having means to clamp it at any adjusted position in reference to the scale, a table rotatable on said support. at .a level below but close to the under side of said toolholder slide, said table having peripheral gradu'ations, means on the support for clamping the table in any position 'after rotation, and means carried by said frame and slide cooperable for releasably locking the frame to the slide, which moves over the stationary scale.

10. A device of the class described, comprising a support having front and rear parallel horizontal ways, a frame having widely spaced portions sliding on the rear way, and having an arm having its outer end sliding on the front way, said arm having parallel ways, one at each opposite side and lying in the same horizontal plane and perpendicular to said front and rear ways, a first scale on the top of the arm, a tool holder held in sliding relation with said ways and against vertical motion and overlying the scale and having a 4 sighting opening downwardly through which the scale can be viewed, and further having an axially vertical opening close to but disposed laterally of one of the ways of the arm and adapted to rigidly hold a tool, means for clamping the tool holder to the arm, an auxiliary way on said support parallel with the front way and having a scale, a slide overlying the second scale and slidably connected with the auxiliary way and having a sighting opening downwardly through which the scale can be viewed, and having means for clamping it at any adjusted position along the way, and a table .on said support below the arm and close to the opening of the holder for supporting an element in operative relation to a tool held by the holder.

11. A device of the class described, comprising a frame slidable on a'support, said frame having an arm, a first tool holder slidable on said arm, a scale also on the arm, said holder having an opening for rigidly holding a tool, said holder having means for clamping it to the arm, a table on said support below said arm, a second or auxiliary arm overlying said table and having a pivot lug releasably engaged in the opening of said holder to allow horizontal swinging motion of the arm over the table, said second arm havin thereon a second tool holder slidable along a scale also on the second arm, said holder having means for clamping it 'to the second arm and having an opening of the same diameter as that of the first mentioned opening for rigidly holding the tool, said second arm having auxiliary supporting means which slidably engages the table to hold the arm parallel therewith, whereby the pivot lug of the second arm can be removed from the opening of the first tool holder, and the tool can be inserted in said opening and whereby the opening of the first tool holder is used for swingingly mounting a second slidable tool holder, the opening of which can then receive the same tool.-

12. A device of the class described, compris ing a frame slidable on a support, said frame having an arm, a first tool holder slidable on said arm and over a scale also on the arm, said holder having an opening for rigidly holding a tool, said holder having means for clamping it to the arm, a table on said supportbelow said arm, a second or auxiliary arm overlying said in the opening of said holder to allow horizontal swinging motionof the arm over the table, and said second arm having thereon a second-tool holder slidable along ascale also on the second arm, saidholder having means for clamping it to the second arm and having an opening for rigidly holding a tool, said second arm having auxiliary supporting means which slidably engages the table to hold the arm parallel therewith.

a support having front and rear parallel horizontal ways, a frame having a substantially elongated portion sliding on the rear way, and having extending from a point near one of its ends, an arm having its outer end sliding on the front way, said arm having two parallel ways perpendicular to said front and rear ways, a first scale on the top of the arm, a cutting tool holder sliding on the corresponding ways and overlying the scale and having a sighting opening downwardly through which the scale can be viewed, and further having axially an opening close to but disposed laterally of one of the ways of the arm and adapted to rigidly hold a cutting tool,'a pair of ways on said support parallel with and near and in front of the front way and having a scale, a slide overlying the second scale and slidably connected with the corresponding ways and having an opening downwardly through which the scale can be viewed, and having means for clamping it at any adjusted position along the scale, and means respectively on the arm and on the slide cooperable for releasably locking the arm rigidly to the slide, and a table on said support below the arm and close to the under side of the tool holder for holding an element on which a delineation is to be cut.

14. In a device of the class described, a support having a circular table rotatable thereon, said table having peripheral graduations, said support having a block having thereon an arcuate vernier associated with said graduations of the table, a slide on the block movable in an arcuate path and having a window overlying the vernier and graduations, and having a reference line by which to facilitate registration of vernier and table graduations, means for clamping the slide to the block in any arcuately adjusted position, said block also having means thereon for releasably clamping the table, including a clamp-operating element accessible at a point near the slide.

15. A device of the class described, comprising a support, a table on said support, a frame movable over the table, a scale on said frame, a pair of coplanar parallel horizontal ways for said scale, one at each side thereof, a slide rigidly held by the ways against vertical motion, said slide having a sighting window downwardly through wmch the scale can be viewed and having a vernier on the margin of the window, and also having means to clamp it to its ways, and having means for releasably but rigidly holding a'tool against vertical motion and in delineating relation to the table, the said ways of said slide 081118 01088 to said table.

16. A device of the class described comprising a base having thereon, a frame comprising first and second arms arranged in L-shaped relation, as viewed from above, a pair of tracks front and rear, parallel with the rear arm and over 13. A device of the class described, comprising and upon which the arms are respectively slidably guided, and a turntable disposed intermediately of the tracks and in substantially tangent relation therewith and over which the -front arm of the frame is movable, the arms being so arranged in relation to the table that one of the arms can be moved to a substantially tangent relation with the table, and when so I related leave the entire area of the table exposed to view.

. table, one of the arms of the L being parallel with and sliding on the rear track and the other arm being perpendicular to and sliding on the front track and extending toward the operator's station, said arms being so arranged in relation to the operator as he stands near the front track, and to the table, that when the frame is at one limit position the entire area of the table can be visible.

18. A device of the class described comprising a base,'front and rear parallel tracks on the base, a drawing table between said tracks, an L-shaped frame slidable on said tracks over the table, one of the arms of the L being parallel with and sliding on the rear track and the other arm being perpendicular to and sliding on the front track, said arms being thus so arranged in relation to the operator as he stands near the front track, that when the frame is at one limit position the entire area of the table can be visible, the last mentioned arm having a scale on its top arranged lengthwise thereof and having a slide guided on the arm over said scale, said slide having asighting opening, means to clamp the slide, and said slide having means for clamping a tool thereto in delineating relation to the table.

19. A device of the class described having a base, having front and rear parallel slide ways, a frame composed of first and second arms arranged in L-shaped relation, a first arm being arranged lengthwise of and sliding on the rear way, and the second arm being arranged perpendicularly to, having its outer and front end sliding on the front way and extending toward 3 the operator's station, a drawing table disposed between the ways and over which the frame moves, the upper surface of said table being substantially in the same horizontal plane as the tops of the slides, and the bottom of said second arm being close to the top surface of the table, a scale on the top of the second arm toward the table, and releasable means on the slide engaging with said annular shoulder to prevent motion of the holder away from the table.

21. A device of the class described, comprising a base having a drawing table thereon, a carriage on an arm movable over said table, a scale on the top of the arm, a slide guided on the arm and having means to clamp it to the arm, a tool holder removably held in an opening in said slide and having a shoulder which limits motion of theholder in a direction toward the table, and releasable means on the slide engaging with said shoulder to prevent motion of the holder away from the table and comprising a lever, means translatably fulcrumming the lever on the slide, said lever at one side of the fulcrumming means being engaged with the shoulder, and means at the opposite side of said fulcrumming means for applying leverage power to said lever.

22. A device of the class described, comprising a base having thereon a circular rotative drawing table marginally graduated, a support on the base having a scale with which graduations of the table are adapted to register, means on the support for clamping said table in relation to the scale, a lever pivoted to the support and having on its free end clamping elements including a first arm over the table and a second arm under the table, said arms and the pivotal axis of the lever being substantially radially related extendinglengthwise thereof, a pair of coplanar 20. A device of the class described, compris ing a base having a drawing table thereon,,zai carriage on said base having an arm movable over said table, a scale on the arm, a slide guided on the arm and having'means to clamp it to the arm, a tool holder rotatably held in an opening in said slide, and having an annular shoulder which limits motion of the holder in a direction to the axis of rotation of the table.

23. A device of the class described, comprising a base having thereon a circular rotative drawing table marginally graduated, a support on the base having a scale with which graduations of the table are adapted to register, means on the support for clamping said table in relation to the scale, said clamping means comprising a lever pivoted to the support and having at its free end a first arm over the table and a second arm under the table and a floating block on the second arm, said arms and block being normally disposed out of engagement with the table, and manual means adapted to simultaneously move the upper arm and block into clamping relation with the surfaces of the table.

24. A device of the class described, comprising a base having thereon a circular rotative drawing table marginally graduated, a support on the base having a scale with which graduations of the table are adapted to register, floating means on the support for clamping said table in relation to the scale comprising a lever pivoted to the support and having at its free end a first arm over the table and a second arm under the table and a floating block on the second arm, means for limiting lever motion to normally dispose the upper arm and block so that theyare out of engagement with the table, means yieldably urging the clamp against the limiting on the slide by which slide-securing pressure can be applied against and substantiallyin the plane I of the ways of the arm, said slide having an opening close to one of the ways of said arm, a

table between the ways, a frame movable over the table on the ways and having an arm, said arm having lengthwise thereof, at opposite sides, parallel ways in the same horizontal plane and facing laterally, a cross-sectionally C-shaped sighting slide on the top of the arm operatively engaged with the ways of the arm, means on the slide by which slide-securing pressure can be applied against and substantially in the plane of the ways of said arm, said slide having an opening immediately adjacent one of the ways of said arm, a scriber holder accurately fitting in said opening, and means on the slide for rigidly securing the scriber holder against axial motion in a direction away from said table, the ways and the bottom of said arm being close to but spaced from the table.

'27. A device 'of the class described comprising, a support having front and rear ways, a rotatable drawing table between the ways, a frame movable over the table on the ways and having an arm extending between the ways and pointing toward and supported on the front way, near which front way the operator stands, said arm having lengthwise thereof, at opposite sides, parallel ways i the same horizontal plane and facing laterally, a cross-sectionally c-shaped sighting slide on the top of the arm having grooves operatively engaged with the ways of the arm, means on the slide'by which slidesecuring pressure can be applied against and substantially in the plane of the ways of said arm, said slide having an opening immediately adjacent one of the ways of the arm, a scriber holder accurately fitting in said opening, and means on the slide for rigidly securing the scriber holder against axial motion in a direction away from said table, the ways and the bottom of said arm being close to but spaced from the table.

28. A device of the class described comprising, a support having front and rear V-shaped ways, a rotatable drawing table between the ways, an L-shaped frame movableover the table and comprising a first arm having a downwardly facing groove slidably engaged with the V-shaped rear way only at two widely spaced points and the second arm extending from the first arm at a point intermediately of the engaging points of the first arm with the rear way,- said second arm having its outer. 'end slidably engaged by a single point of contact with the V-shaped front way, said second arm having lengthwise thereof, at opposite sides, parallel V-shaped ways in the same horizontal plane and having their crests pointing laterally, a cross-sectionally C-shaped venier sighting slide on the top of the second arm having V-shaped grooves operatively engaged with the V-shaped ways, means on the slide by which slide-securing pressure can be applied against and substantially in the plane of the crests of the ways, said slide having an opening immediately adjacent and substantially tangent to one of the v-shaped ways of said second arm, a scriber holder accurately fitting in said opening and means on the slide for rigidly securing the scriber holder against axial motion in a direction away from said table,

the ways and the bottom of said second arm being close to but spaced from the table.

OSCAR C. HEDIN.

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