US2648908A - Drawing machine - Google Patents

Description

1953 o. M. STONE 2,648,908

DRAWING MACHINE Filed July 14, 1950 u 6 Sheets-Sheet 1 3 PLAN v/zw 3 A2 (PP) PICTURE PLANE A A, A2 A3 A f REGULAR FRONT T h 5 ELEVATION VIEW PERSPECTIVE 5,4515 L/IVE wzw PIC TURE IN V EN TOR.

OLIVER M STONE 0. M. STON E DRAWING MACHINE Aug. 18, 1953 r 6 Sheets-Sheet 2 Filed July 14, 1950 INVENTOR.

OL/VER MSTONE ,fiw Jg-xjwr 6 Sheets-Sheet 3 O. M. STONE DRAWING MACHINE Aug. 18, 1953 Filed July 14, 1950 INVENTOR.

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8, 19 3 o. M. STONE 2,648,908

DRAWING MACHINE 6 Sheets-Sheet 4 Filed July 14, 1950 /3a 7 a 6 \f @u@% minimum IN VEN TOR.

OLIVER M STONE 1953 o. M. STONE 2,648,908

DRAWING MACHINE Filed July 14, 1950 e Sheets-Sheet 5 F/G. 9 H6. 8

INVENTOR.

OLIVER M. STONE 8, 1953 o. M. STONE 2,648,908

DRAWING MACHINE Filed July 14, 19 0 e Sheets-Sheet e INVEN TOR.

OL/VER M. STONE Patented Aug. 18, 1953 UNITED STATES PATENT. OFFICE DRAWING MACHINE Oliver M. Stone, Cleveland, Ohio Application July 14, 1950, Serial No. 173,797

23 Claims. 1

This invention relates to drawing apparatus employed by draftsmen in making perspective drawings.

There are several well known methods or principles by which perspective drawings may be constructed such as the so-called vanishing poin method and the visual ray method. Manual construction of perspective drawings according to these methods requires considerable time and operator skill. Efforts have been directed toward the building of drawing machines with the object of lessening the time required and simplifying the operations involved in making these drawings. While these efforts have resulted in machines that have succeeded to some degree in shortening the drawing time necessary to manually construct perspective drawings, the machines generally are quite costly, are bulky and cumbersome to handle and to operate, andin several instances must be supplemented by manual graphical construction on the part of the operator.

An object of the present invention is to provide a perspective drawing machine with which accurate perspective drawings may be made from regular plan and elevation views without the aid of construction lines. tion are the provision of a machine that is simple to operate and which requires nospecial skill in the operator; the provision of a machine which permits the operator to make stereoscopic pairs of perspective drawings substantially simultaneously and rapidly; the provision of a machine which permits the operator to plot all spacial points of an object in the perspective view, including those points on the plan view of the object that lay in or close to the picture plane; the provision of a machine which utilizes regular plan and elevation views of the object to be drawn and which permits the plan and elevation views to be properly oriented with respect to the operator and to stand in the same direction; the provision of a machine which includes a minimum number of bars and beams and structural components whereby to facilitate and simplify operation of the machine; the provision of Other objects of this invenvision of a machine which includes means for adjusting all members. for alignment.

Other objects of the invention will become apparent from the following description of a preferred form thereof, reference being had to the accompanying drawings in which: Figure 1 is a diagram illustrating the theory of the present invention; Figure 2 is a simplified schematic diagram of a drawing machine embodying the present invention; Figure 3 is a plan view of the drawing machine showing the plan pointer means in the initial setting position; Figure 4 is similar to Figure 3 showing the plan pointer means in a plotting position; Figure 4A shows a pair of perspective drawings constructed with the aid of the drawing machine; Figure 5 is a plan view of a portion of the machine showing the carriage and associated components; Figures 6 and 7 are vertical sections taken substantially on the lines 6-6 and 'I-'I, respectively, of Figure 5; Figure 7 8 is an enlarged view of a portion of Figure 6 a machine that may be set up and disassembled I showing details of the swivel plate assembly; Figures 9, 10 and 11 are vertical sections taken substantially on the lines 9-9, I 0-I 0 and I I--I I, respectively, of Figure 5; Figure 12 is a plan view of a portion of the machine showing the slide piece and the connection of the elevation beam to the clamp member; Figure 13 is a vertical section taken on the line II-II of Figure 12; Figure 14 is a plan view of a portion of the machine showing the support plate assembly and the support assembly for the elevation beams; Figure 15 is a vertical section taken on the line I5-I5 of Figure 14; Figure 16 is a side elevation of a foot pedal employed in connection with construction of stereoscopic pairs of perspective drawings, a portion of the pedal being broken away to show details of construction; and Figure 17 is a schemati-c view of certain components of the drawing inachine showing the position of cords and puleys.

The perspective drawing machine which embodies the present invention is designed to operate on the revolution principle of graphical construction. This principle will be understood by first considering the actual'condition of a human observer viewinga distant object such as a house. The house and the observer both stand on a common base, the ground, and both project upwardly from it into the air; The observers view of the house, that is, the view which his eye sees, is made up of many separate views of the respective points on the house; the separate views meld together to form the whole picture. 'Thus lines of sight or visual rays from his eye to the many points on the object define or outline the picture he sees. This picture is called the perspective View.

If a perspective drawing machine were constructed to simulate the actual condition of an observer viewing an object, certain of the component parts of the machine would necessarily project above the base plane by a distance representative of the height of the observers eye above the ground. such a machine would be difficult to operate and hence impracticable. According to the present invention, however, this machine is made practicable by simply revolving the vertically projected components of the machine into the plane of the base. The part of the machine which represents the observers eye will then lie substantially in the plane of the base; however, the length of the respective lines of sight or visual rays remain unchanged, that is, the length of these rays represent true distances between the observers eye and points. on the object.

Referring now to Figure 1, the object selected for showing the method used in plotting the points in the perspective view is a rectangular prism. It will be understood throughout the description of the machine that objects other than rectangular prisms may be used as the subject of a perspective drawing on my machine. The rectangular prism therefore is illustrative of but one of many objects that may be drawn on my machine and is selected herein for illustration because of its simplicity and for clarity of explanation.

The location in the perspective view T of any point on the prism may be found by applying the following graphical method to the location of point A1 on the rear corner of the top surface of the prism. A line representing the picture plane is first drawn. The plan view P is then orientated with respect to the picture plane to the desired angle for making the perspective view. The point E is located by spacing same from the plan view P by a distance representative of the horizontal distance between a human observer and the object being viewed. A line 7 is then drawn to connect the chosen point A1 on the plan view with point E. The line 1" is the horizontal projection of the visual ray from the point of observation to the object.

Point F designates the intersection of line A1E with an arbitrary vertical reference plane, called a pictureplane, which intersects the base plane along the line PP between the plan view P and the horizontal projection E of the observation point D. From F, a line p perpendicular to the line PP is drawn. The line p locates the position of point A1 on the perspective view in a direction parallel to the picture plane; that is, the exact location of point A1 on the perspective view lies somewhere along the line 10.

With the line A1E drawn, point B is located by laying off on a perpendicular to the line AlE a distance it which represents the height of the point A1 above the ground or base line. This distance it is obtained from a regular elevation view S. The point D is then located by laying oil a perpendicular to the line A1E through the point E, the perpendicular having a length equal to the height of the observation point above the ground or base plane. Thus, the line DE represents the height of the observers eye above the ground. Points B and D are then connected by a line to complete the trapezoid AIEDB.

The next step is to lay oif a perpendicular to the line AlE through point F and extend that perpendicular until it crosses the line BD, thereby locating point C. The length t of the line CF represents the height of the point A1 in the picture Plane above the base line. By laying off the distance 1? above the base line and on the line 32 which has been drawn previously, the position of point A1 in the perspective view T is located.

Having thus located one point in theperspective view, the other points may be-located in the same manner, the distance DE remaining constant throughout the drawing operation. It will be noted that the height h will remain the same for all points on the top of the rectangular prism but that the length if of line CF will vary. As other points on the prism at a difierent distance or height above the base line are to be drawn, the length it of the line A113 is changed accordingly.

Figure 2. is a simple schematic diagram. of the proposed perspective drawing machine embodying the present invention. The diagram is shown in three dimensional form, the dotted lines representing components of the machine whichjnormally would project upwardly from the base plane if the actual condition of an observer was to be simulated; Whenever convenient, reference letters indicating the, intersection of construction lines in Figure 1 are used in Figure 2 in the description of corresponding component parts of the drawing machine.

The eye of a human observer is represented by D. The line of sight of the observers; eye to the top of the rectangular prism being viewed is indicated by the line D B. The true perspective height of a point on the object will be the height of the point of intersection of the ob server's line of sight with the picture plane above the base line. This is indicated by the point C, the perspective height being the length of C'F; If the trapezoid DB'A1E is revolved about the intersection of the plane of this trapezoid' with the base plane, thats is, revolved about the line AiE until the trapezoid lays in the plane of, the base, the actual condition of an observer viewing, an object is maintained without distortion and without variation or change in the true distances representative ofthe actual physical observation condition. Thus, the trapezoid DBA1E is the vertical plane D'E'A1E revolved into and lying in the horizontal or base plane.

It will be noted that the length of C'F represents the true observed height of the top rear corner of the prism inthe picture plane; therefore, CF kewise represents the true observed height of this point on the prism. similarly, for other points on the top of the prism,

the length ofline-CF will represent'trueobserved heights of selected points on the prismabove the base plane and inthe picture plane. Changesin the length of the line CF are directly proportional to the differences in observed heights-cf" various points on the prism with respect to a baseline. As will be explained in detail later, variationsin the length of the line CF'are utilized to accomplish the mechanical plotting of points in the perspective view.

Before describing the details ofconstruction of the perspective drawing machine which operates on the above described principle of construction of perspective drawings, it will be helpful to note that the schematic diagram of Figure 2 represents a simplified skeleton of the finished machine. The point E is a pivot point about which the trapezoid DBAiE is adapted to pivot. The mechanical components DE and CF and A13 remain perpendicular to the component EFA1 during all plotting operations. The intersection of components EAi and CF, that is the point F, remains in the picture plane during pivotal movements of the components about the point E. The length of components EF, DE, and 3A1 are adjustable. The intersection of components DB and CF, that is the point C, is connected to a tracing element in such a manner that variations in the length of CF produce corresponding variations in the position of the perspective plotting means toward and away from the picture plane.

APPARATUS As shown in Figures 3 and 4 the perspective drawing machine is mounted on a fiat L-shaped drawing board or base B which is adapted to be supported in an elevated position for convenience for the operator. Extension. B of the drawing board B may be hinged to the main body of the board in order that the same maybe folded into a convenient size for storage. An elongated channel shaped main guide bar I is removably fastened at its ends to the base 13 and extends transversely of it. A carriage generally indicated at 2 is supported on the drawing board for movement thereover and along the guide bar I. A channel member 3 is secured to the right end portion of carriage 2, as viewed in Figures 3, 4 and 5 and extends from the carriage parallel to the base B and perpendicular to the guide bar I.

The channel member 3 moves with the carriage 2 over the base B and supports a stem assembly 4 and an extension bar 5 for movement in directions perpendicular to the guide bar. An elevation ruler E and a perspective plotting member I are connected to and extend from stem assembly 4 for movement therewith in directions parallel to and perpendicular to the bar I. The elevation ruler 6 spans a regular elevation view S of the object to be drawn, which view is disposed on or attached to the surface of base B under the ruler 6. The member I likewise spans a sheet of drawing paper on which the perspective View T of the sheet is ultimately to be drawn. An auxiliary elevation ruler 8, if desired, may be connected to the upper end of the extension bar 5 as viewed in Figures 3 and 4 to permit an additional regular or auxiliary elevation view S to be used in conjunction with the regular elevation view S in the construction of the perspective drawing.

Mounted on the left end of the carriage as viewed in Figures 3, 4 and 5 is a swivel plate assembly 9 which is adapted to pivot in a horizontal plane about a vertical axis indicated at Ill. Guide rods II are connected to the assembly 9 and project therefrom away from carriage .2 parallel to base B. Rods I I are parallel to each other and support slide piece I2 for sliding movement thereover. A plan beam I3 extends trans versely of the carriage and is supported for transverse movement on swivel plate assembly 9. Plan beam l3 therefore is adapted to slide across the carriage 2 as well as to pivot with respect to the carriage about the vertical axis IE3. A height rod I4 which is connected to the end of plan beam is extends therefrom at a right angle to the longitudinal axis of beam 53, and supports a clamp I5 which is adapted to be moved over and clamped in selected positions on rod I4. A pointer I6 clearly shown in Figure 4, is disposed on the end of the plan beam I3 adjacent the height rod 6 I4, and is used as a means for locating various points on the plan view P of the objectto be drawn.

A support plate assembly generally indicated at I? is removably anchored to extension B of base B and has a yoke member I8 which pivots in a horizontal plane about a vertical axis indicated at I9. Plan beam I3 is supported by the yoke I8 and is free to swing or pivot about the axis I9 as well as to move in directions transversely of the assembly H. An elevation rod 23 extends from assembly I! perpendicular to the longitudinal axis of plan beam I3 and is connected to the assembly I'I so as to pivot about axis I9 along with yoke I8. Rod 25! carries asupport assembly 2i whose position on rod 20 is adjustable. Assembly 2! supports elevation beam 22 for pivotal and transverse sliding movement relative to rod 28. Beam 22 extends substantially transversely of guide bar I and is pivotally connected at one end to clamp I5. The beam 22 extends through slide piece I2 so as to have a pivotal and sliding connection therewith; that is, slide piece I2 moves along guide rods I I as a result of a lateral shift of the cross over points of elevation beam 22 and guide rods II when pointer I6 is moved to various points on the plan view P. Slide piece i2 is tied by cords 96 and 91 or other suitable means to stem assembly 4 so that movements of the piece I2 on guide rods I I are exactly duplicated by movements of assembly 4 and consequently ruler 5 and member 'I in directions perpendicular to guide bar I.

Having briefly described a general layout of my perspective drawing machine it will be helpful to note that some of the mechanical components described above have their counterparts in the schematic diagrams of Figures 1 and 2. For example, the pivotal axis Ifl of the swivel plate assembly 9 corresponds to the point F; slide piece I2 corresponds to point C on the schematic diagrams and the variable distance between piece I2 and axis ID of the swivel plate assembly corresponds to the variable length t of the line CF in Figures 1 and 2. Plan beam I3 represents the line A1E which is the horizontal projection of the visual ray DB; elevation beam 22 represents the visual ray DB; height rod I4 corresponds to the line AB and the selected position of clamp I5 on height rod I4 is comparable to point B. The pivotal axis I9 of yoke I8 in assembly I? corresponds to point E and elevation rod 2!! corresponds to line DE. The adjustable position of pivot member 2I on elevation rod 20 is represented by the point D. Elevation beam 22 which is pivotally connected to clamp I5 and which crosses guide rods II and slidingly and pivotally engages slide piece I2 on rods II, is represented by the line DB or the visual ray which terminates at point B correspondingly to clamp I5, crosses line CF corresponding to rods ll at point C represented by slide piece I 2.

The following is a detailed description of the various components that make up my perspective drawing machine. Referring now to Figures 5 and 9, the main guide bar I consists of a straight channel shaped member which extends the full length of the drawing board B and is removably secured thereto at its ends by suitable means such as clamp screws 25, see Figures 3 and 4. The carriage 2 which rides along the main guide bar consists of two channel members 30 and 3| disposed on either side of guide bar I and secured together by a plate 32 fastened by.

screws or the like to their top sides. The inner legs 33 and 34 of channel members 30 and 3|, respectively, are spaced from the sides of the guide bar I and antifriction rollers 35, 36, 31 and 38 carried 'by the channel members 36 and 3| so as to rotate about vertical axes maintain rolling'contact with the sides of guide bar I to guide the motion of carriage 2 along the guide bar with a minimum of resistance. The carriage 2 is supported for movement on the base B preferably by two sets of antifriction wheels 39, 4B, and 4|, 42 which rotate about shafts i3 and 44 and 45 and 46, respectively, mounted on opposite ends of channel members 30 and 3i. These wheels are disposed to rotate about the horizontal axes of the respective shafts and maintain rolling contact with the surface of the base B. This construction permits carriage 2 to have guided, substantially frictionless movement over the base B. It will be understood that the rollers described above are constructed so as to minimize frictional resistance between the carriage, guide bar and base. Rollers of this type are also employed on other components of the drawing machine to support and guide same in movements relative to each other and to the base. It is desirable that friction between moving parts of the machine be minimized not only to facilitate operation of the machine but also to increase accuracy in the construction of perspective drawings.

(a) Elevation ruler and plotting member In order to guide movements of the elevation ruler 6 and the plotting member 1 parallel to and transversely of guide bar I, channel member 3, see

Figures and 10,. which extends away from guide bar I and spaced from base B is connected at one end thereof to the carriage 2. The opposite end of channel member 3 has a supporting wheel 51 rotatably mounted thereon and which is adapted to roll on the top. surface of base B to support member 3 for movement over base B in directions parallel to guide bar l. Member 3 extends under plate 32 of the carriage 2 and is attached to it by three screws. 52 which is attached to channel 3| for rotation about a horizontal axis project slightly above the top surface of plate 32 to support an extension bar 5. Member 3 constitutes a base on which the elevation ruler 6 and the plotting member 7 move toward and away from the carriage 2, as will be described below.

A stem assembly generally indicated at 4 is sup-- ported on member 3 for movement thereover in directions perpendicular to guide bar I. Stem as.- sem-bly lccnsists of spaced side elements 56 and 57' connected together by a plate 53, see Figures 5, 11 and 17. Elements 56 and 5! are disposed on opposite sides of channel member 3 and spaced slightly therefrom and have rearwardly extending flange portions 58 and 60, respectively, in

which recesses are formed to accommodate guide rollers BI and 62. Rollers 6! and 62 rotate about shafts 63' and 64 connected to flanges 59 and 6B and maintain rolling contact with opposite sides of member 3 to guide movements of assembly 4 therealong. Plate 58 has notches 65' and 66 formed therein toreceive wheels 61' and 68 which roll on the top surface of channel member 3' and support stem assembly 4 for movement in directions perpendicular to guide bar I. This movement is also controlled by two adjustable rollers 69 attached to plate 32".

Elevation ruler 6 which consists of bar T0, a

fine wire- H and space wire supporting posts 72' Rollers 53 mounted on the bracket.

and-'13-is connected to and extends from the stem assembly 4' so as to move therewith. One end of bar Hi is secured to element 56 of stem assembly 4 by suitable means such as screws M. The other end of bar has a vertically disposed pin 75, having a smooth rounded end 15a in contact with surface B, see Figure 11', to support and permit free movement of the elevation rulerover base B. The ruler 6 spans a regular elevation view S of the object being drawn, the wire H serving as a straight edge to facilitate accurate setting of other parts of the machine to correspond to a particular height on the object. The plotting member 1- consists of a bar 7'8 and plotting guides 11 and 78, see Figures 3 and 4, whose positions on bar 16 are adjustable. Bar 76 is secured at one end to element 57 of the stem assembly by screwmeans' l9 and has a pin 8&1 similar to pin 15 in ruler 6' at its outer end to support same on base B. Thus, member I and ruler 6' may move directly withthe stem assembly parallel to channel member 3 and also in directions parallel to the guide bar I in response to movements of the carriage 2 therealong. V-shaped recesses 81 and 32 in guides 11 and 78, respectively, guide the point of a marking object, such as a pencil, for the purpose of plotting points on the perspective View on a suitable sheet of drawing paper underlying the plotting member.

In order to utilize an additional and/or auxiliary elevation view in connection with making perspective drawings, an auxiliary elevation ruler 8, shown clearly in Figures 3 and 4, is provided. Ruler 8 is esscntialiy the same as ruler 6 and overlays an auxiliary elevation view S fastened to base B on the opposite side of the carriage from elevation view S. In order to coordinate movements. of auxiliary ruler 3 with movements of stem assembly t, an extension bar 5 which overlays channel member 3 is connected to plate 58 of the stem assembly by screws 85. The bar 5 is supported on rollers 53 adjacent the carriage 2 so as to move freely in directions perpendicular to the main guide bar in response to similar movements of stem assembly 4. The outer end 5a of the bar 5 is suitably secured to ruler 8 which extends therefrom parallel to ruler 6. A. pin 85 similar to pin 15 of ruler 6 is carried by the outer end of ruler 8 and supports same for movement over the base B. The ruler 8 with the wire 83 serving as a straight edge overlies an auxiliary elevation view 3 of the object being drawn. Auxiliary ruler 8 functions in the same manner as elevation ruler 6 and provides greater flexibility in the machine by permitting auxiliary elevation views to be used conveniently in the construction of perspective drawings.

In order to effect movements of the stem assembly 4 along channel member 3 in directions perpendicular to the main guide bar I, a pulley 9G is mounted on channel member 3 remote from the carriage 2,. the pulley being mounted so as to rotate about a vertical axis, see Figures 5 and 1'7. Similar pulleys s: and 92 are mounted on the carriage 2 near the point of connection of channel member 3 to the carriage. Pulley 9! is spaced from the top of carriage 9i by means of a plate 93 and a spacing block 94. The other end of plate 93 is formed to cover the upper end of a shaft 95 suitably fastened to plate 32 of carriage 2 and: about which the lower pulley $12 is disposed to rotate. The axes of pulleys ill' and 92' are aligned in a plane parallel to the longitudinal axis of the main guide bar I and, as with pulley 90,. have annular V-shaped recesses on their peripheries for receivingcords 96- and 97 there-' around. The ends of cords 96 and 91 are connected to the slide piece I2 and to the stem assembly 4 and are disposed around pulleys 90, 9E, 92 and I64, the latter being mounted at the extreme outer end of guide rods l I, see Figures 3, 4 and 1'7, to effect movement of the stem assembly 4 in directions transversely of the main guide bar in response to movements of the slide piece I2 along guide rods II. This movement of the stem assembly 3 by cords 96 and 91 will be xplained in detail later.

(b) Swivel plate assembly In order to support plan beam 53 for pivotal and sliding movement with respect to the carriage 2 during plotting operations, a swivel plate assembly 9 is mounted on the left end of .the carriage as viewed in Figures 3, 4 and 5. The assembly 9 consists of a swivel plate I88, and guide members lei and I32, each of which is secured by screws or the like to the plate Ills. Members NH and I82 preferably are made of short lengths of aluminum having horizontally disposed legs I33 and I04, respectively, which are fastened to the plate Iilfi. Members Illi and I62 also have vertically disposed legs H35 and I85 respectively, which are laterally spaced so as to receive and guide the plan beam I3 therebetween. Guide rollers ml and its on the members Hit and I62 respectively engage the sides of the plan beam and a transverse supporting roller I69, see Figure '7, carried by a pin between plate 469 and members IiiI and IE2 engages the underside of the plan beam to facilitate sliding movement of same with respect to the carriage.

Guide rollers Hill and M38 as well as other guide and supporting rollers associated with other components of the machine are mounted thereon by means of eccentric sleeves, adjusting screws and the like which permit the axes of these rollers to be shifted slightly for the purpose of effecting accurate adjustment of same. For example, rollers IE8, see Figures 5, 6 and '7, are mounted on eccentric sleeves Illila which have hexagonal shaped heads to facilitate turning same to effect the adjustment rollers lite against the side of plan beam I3.

As shown in Figure 5, plate tilt is preferably formed with a curved outer edge Hills and a projecting portion lit about which the plate is adapted to swivel or pivot. The plate It?! is supported for pivotal movement by a roller ill, see Figures 6 and '7, which is journaled in channel member 36 of the carriage 2 and which projects through slots in the members 38 and 32 to supl portingly engage the underside of the plate its. Another roller II 2 disposed to rotate about a horizontal axis is mounted on a bracket I53, secured to plate 32 of the carriage and engages the top surface of the plate use and in conjunction with roller Iii guides the plate its in its pivotal movements.

The projection iii of the plate IE8 is provided with an aperture 5 id, see Figure 8, through which the shank lit of a pivot stud H5 is adapted to extend. The upper end of the shank MS has a flange II'I which abuts the top surface of plate I06 and the lower end of shank MS is threaded as indicated at i 58. The shank Hi5 of pivot stud I I5 also extends through the carriage plate 32 which extends under and is slightly spaced from the swivel plate Hit and through the web 3i (a) of carriage channel member M. A nut H8 fitted into a recess in the web 3| (a) enga es the threaded portion I if) of the pivot stud lit and 10 draws the members together. The vertical axis of the pivot stud H5 which coincides with the axis IE! of the assembly 9 is the axis about which swivel plate I and consequently the assembly 9 rotates.

In order to guide the cords 96 and El through the swivel plate assembly 9 so that the cords at all times throughout the drawing operations "remain in the plane of the axis Ill, a cord guide post assembly generally indicated at I253 is provided, see Figures 6 and 8. The guide assembly I20 consist of an upper pair of guide rollers Ill and I2Ia and a lower pair of guide rollers I22 and I22a mounted on and disposed to rotate about the shanks I23 and I24 of screws I25 and 526. The guide rollers I2I and mm and I22, and I225; are positioned between blocks I2; and I25 and plate Hill through which screws I25 and I26 pass, the blocks serving to properly position the rollers with respect to each other. Rollers I2! and I22 have internally'disposed bearings, not shown and are thus free to rotate about the axes of screws I25 and I26 with a minimum of friction. Washers I29 and I39 space the rollers from the blocks.

As shown in Figure 8, the peripheries of rollers I20, E2961, and I2I, IZIa are spaoedfrom each other and equally about the axis it of swivel plate I08 thereby defining spaces I35 and I32. The space I3I is suificiently large to permit cord 97 to pass therethrough while the peripheries of rollers I25, I2Ia lightly engage the sides of the cord. In like manner the space I32 between rollers I22, I22a is just largeenough to permit cord 96 to pass while maintaining light engagement with each of the rollers. -With this arrangement and spacing'of the guide rollers in the cord guide post assembly I29, cords 96 and 9! will pass through the axis of rotation of swivel plate Hill at all times throughout the operation of the drawing machine, that is, for the various angular positions of the swivel plate assembly about the axis It. It is of interest to note that the picture plane described in connection with Figures l and 2 is the vertical plane containing pivot axis I6 as well as. the reach of cords 96 and ill between pulleys 91, 92 and guide post assembly I26. The picture plane is parallel to the direction of travel. of carriage 2 on guide bar I and so pivot axis It remains in the picture plane at all times during operation of the machine.

A position plate I33, see Figure 6, is disposed in a slot in the underside of the guide bar 5 and secured thereto beneath swivel plate assembly 9'. Plate I33 has a forwardly projecting portion I3 3 having a recess IMa underlying pivot axis Id of the swivel plate assembly. Recess i3 ia is vertically aligned with the pivot axis iii and is of suflicient size to admit plan pointer I6 associated with the plan beam I3. When plan beam I3 is moved so as to position pointer It in recess I34a, the vertical axis of the pointer will coincide with an extension of pivot axis iii, and the pointer will lie in the .picture plane. With pointer I6 disposed in recess i3 la, the machine is in the initial setting position shown in Figure 3; while the pointeris in this position, adjustment of the position of other components of the machine may be made to adapt the machine to plot points at different heights above the base line. The purpose of the initial setting position will be explained more fully in the description of the operation of the machine. 7

' The end I3a of the plan beam I3 adjacentthe carriage 2 is provided witha post'generally indicated at I35 to facilitate movement of "the plan pointer I during location of points on the plan view P. The post I55 consists of a lower sleeve I 37 projecting through an aperture 1.55 the plan beam I3; and an upper sleeve I35 secured to the sleeve I37 by screws I45 and 114011 and having a flange 739a which'may be conveniently grasped in the fingers of the operator. Disposed within the sleeves I37 and I 35 is a vertically slidable stud member I42 having an enlarged central bearing portion I41. The upper end of stud I42 is threaded to receive a finger knob I43 by which stud I42 and this pointer I5 may be depressed. A spring I44 is disposed between the upper sleeve I39 and knob I44 concentrically of stud I42 to yieldingly urge the stud 42 upwardly in the post. The other end of the stud member is also threaded and passes through an appropriate aperture in an extension piece I45 to which pointer I6 is fastened. Lock nuts I 46 secure extension piece I 45 on the stud I42. Pointer I5 is normally 'urged upwardly away from the top surface of the base .B by the action of spring I44 on stud I42. During tracing operations when it is desired to bring pointer I5 in contact with a particular point on the plan view 1?, knob I43 is depressed against spring I45 and pointer I6 is moved into contact with the plan view.

A block I47 is suitably secured to the under.- side of the end I5a of plan beam I3 by screws I48 and I40a. and has a .hole I49 drilled therein perpendicular to the longitudinal axis of plan beam I3 for receiving the end of height rod I4. The height rod I4 is removably retained in hole I49 of the block I47 by a set screw I50. Rod I4 projects from block I47 and is spaced from and substantially parallel to the plane of base B. A clamp member I5, shown in Figures 12 and 13, is supported for movement over and adapted to be clamped at selected positions along the height rod I4. The member I5 has a clamping portion I 52 which is slotted at I53 and which has .a transverse hole I54 passing therethrough intersecting the slot I55 and through which height rod I4 extends. Projecting upwardly from clamping portion I52 is a post I55 having .a flanged portion I55a fastened to the top surface of portion I52 by screws, not shown, and a threaded stud I55 disposed within post I55. The lower end of stud I55 threadedly engages portion I52 of the clamp below the slot I 53. Normally, rod I4 fits loosely in hole I54 sothat clamp member I5 may be moved to any selected position on rod I4. To secure clamp I5 in position on rod I4, knob I57 and consequently stud I5 are turned about their common vertical axis which results in drawing the slotted portion I52 tightly around rod I4. Knob I57 and post I55 provide a convenient means for manipulation of the clamp by the operator.

The clamp I 5 also has an extension portion I 58 projecting therefrom which has a pivot hole I59 formed therein. Extension I58 overlays the end of elevation rod 22 and is pivotally connected v thereto by a pin I60 disposed in hole I59 of the extension I53 and an aligned hole I6I in the end of elevation rod 22. The extension portion I58 of clamp I5 is adapted to slide under slide piece I2 with the axis of pin I 60 in alignment with the axis of pivot sleeve I77 of the slide piece I2 as shown in Figures 12 and 13 when the pointer I5 is in the initial setting position. When pointer I6 is in the initial setting position, the common i2 axis of pin I60 and sleeve I77 lies in the picture plane.

The slide piece I2 is supported on and guided for sliding movement along a pair of guide rods I I. These rods, preferably having a circular cross section, are spaced from and parallel to each other and are connected to the swivel plate assembly 9 so as to pivot about the axis I5 the-reof. The rods II extend outwardly from the as- .sembly 9 substantially parallel to the base B and have their longitudinal axes perpendicular to the longitudinal axis of plan beam It at all times during plotting operations. The end portions of rods I I adjacent the assembly 5 extend through apertures in the legs I 55 and I 55, see Figures 5, 6 and '7 and are fixed thereby by a clamp block I52. Block I 62 is fastened to guide member MI by suitable means such as screws, and is provided with a pair of holes in which the rods II pass and are clamped. The outer ends of rods II remote from the assembly 9 are fastened in a link I53. A pulley I64 mounted on link I53 for rotation about a horizontal axis is similar to pulleys 95, 5i and 52 described previously, and acts as a direction reversing means for cord 57.

The slide piece I2 which rides or slides on the guide rods II consists of a top plate element I65 connected to a front slide block I57 and rear slide blocks I58 and IE5. The blocks I57, I53 and I59 are provided with transverse apertures or holes for slidingly receiving guide rods II to support the slide piece I2 in movements thereover. Guide rollers I and I7! are mounted on a bracket I72 carried by the front block I67, on its underside, the guide rollers being rotatable about vertical axes with their peripheries in contact with opposite sides of elevation rod 22 to actuate slide piece I2 by movement of rod 22 with respect to guide rods I I. Bracket I72 is pivotally connected to the front block I57 by means of a pivot sleeve I77. This construction of the slide piece I 2 permits elevation rod 22 to move transversely of the slide piece and at the same time to pivot about the axis of sleeve I77. Stud I73 and lock nuts thereon retain the pivot sleeve in the aperture in the front slide block I 57.

An aperture I74 extending through the front block I57 of slide piece I2 parallel to the guide bars II is formed to permit cord 55 to pass through the slide piece assembly on its way to the pulley I54. The aperture I74 also extends through the pivot sleeve I77 as shown in Figure 13 so that the cord 55 at all times passes through the axis of pivot sleeve I77. Side plates I75 and I76 are secured to the outer edges of the slide piece I2 and furnish a means for tying the ends of cords 96 and 97 to the slide piece 72. The

points of connection of cords 55 and 97 to side plates I75 and I75, respectively, are aligned and lie in the vertical plane of the axis of pivot sleeve I77.

(0) Support plate assembly The plan beam I5 is supported remote from the carriage 2 on a support plate assembly generally indicated at I7. The support plate assembly I7 is connected to the edge of the drawing board extension B and not only pivotally and slidingly supports plan beam I3 but also includes means to limitedly shift the rear support of plan beam I3 and elevation rod 22 in directions parallel to the main guide bar I, that is, parallel to the picture plane, to facilitate the making of stereoscopic pairs of perspective drawings as will be explained more fully below.

Referring now to Figures 3, 4, 14 and 15, the assembly I? includes a channel member I19 mounted on and extending along the edge of drawing board extension B and secured thereto by screws I89 which engage opposite sides of the extension B. A reinforcing channel member IBI is secured in back to back relation with chan-- nel member I79 as by screws or other suitable means not shown and thus members I19 and I8I together form an I beam on which the other components of assembly H are anchored. Strips I82 and I83 are secured by screws [92a and I830, to and extend transversely of members I19 and ISI and have screws I 84 and I95 which bear on extension B and provide for adjusting the assembly to the base. Screws I89, I94 and I85 have knobs as shown to facilitate tightening and loosening of same by the operator during assembly and disassembly of the machine and removal of same from the drawing board.

A supporting block I85 fastened to the top flanges of members I19 and [BI by screws Ififia extends parallel to the edge of drawing board extension B and has a pair of holes, not shown, drilled transversely therethrough for receiving and supporting rods I87 and I 89. Rods I 87 and IE8 are held tightly in block I85 by set screws, not shown, and thus are fixed in position with respect to the case B. Rods I3? and I89 are supported to extend transversely of the edge of base B parallel to guide bar I and thus parallel to the picture plane and in turn furnish supports for other parts of assembly II.

The outer ends of rods I81 and I88 pass through a terminal clamping block I89 wherein they are tightly secured by screws I99. Blocks I93 and I93a which serve as a stop means to limit the sliding of yoke I9 on the rods I8? and I88 are mounted on the outer ends of rods I8? and I89 that is, to the right as viewed in Figures 14 and 15, and have transversely drilled holes therein, not shown, which guide the blocks I93 and I 99a for movement over the rods I8! and I88. A top plate I94 furnishes a base for movement of supported parts on rods I81 and I88 and is se- L cured at one end to the tops of blocks I93 and IBM and at its other end to similar slide blocks not shown, which are likewise adapted to slide along these rods. The edge of plate I94 underlying plan beam I3 is curved as shown at I9 ia in dotted lines to provide a supporting surface for a smooth bearing plate IS'I on which yoke I8 rests and pivots.

A cylindrical head I92, see Figure 15, is disposed on the underside of top plate I94 and is movable therewith and has a pivot shaft I95 projecting vertically therefrom about which the pivoting action of assembly I? takes place. The pivot shaft I96 has an enlarged bearing portion I95 which passes through an appropriate aperture in plate I9fi which forms a bearing for pivotal movement of shaft I96. The axis of shaft I96 constitutes the pivotal axis I9 about which the rearwardly extending portion of plan beam I3 pivots during operation of the machine. The yoke I9 has a split end portion 19a which is nonrotat-ably clamped to the enlarged portion I95 of shaft I96 by screw I99. The yoke I3 is recessed as shown at I99 to permit the mounting of supporting rollers 299 which contact the underside of plan beam It to support and to facilitate sliding or" the same over the assembly IT. A block 29I is secured by screws 29 la to the underside of the inner end of yoke I8, that is, the left end of yoke I9 as viewed in Figure 5, to furnish an intermediate support and adjustment for elevation rod 20 which is also held in the cylindrical head I92 of the pivot shaft by a set screw. Thus, the yoke I8, plate I94 and the pivot shaft I96 are adapted to be moved or shifted over supporting rods I81 and I88 and parallel to the picture plane.

Yoke member I9 has fixed thereto a pair of laterally spaced vertically extending flange members 292 and 203 between which plan beam I3 extends and is adapted to move. Roller blocks 294 and 295 are secured externally to flanges 292 and 293, respectively, and are provided at their ends with guide rollers 295, 297, 298 and 209 which guide the plan beam I3 in its transverse movement over assembly Ii. Roller block 295 is mounted on pivot shaft I96, as shown in Figure I5, and locked thereon by lock nuts 2 I 9 to further stabilize the pivoting of plan beam I3 about shaft I96.

In order to limit the amount of movement of the yoke IS on rods I81 and I93, blocksl93 and I93a are provided as heretofore mentioned. Clamping screws H2 and 2I3 having knobs 2M and IMF, respectively, are threaded through opp-osite ends of block I93 and are adapted to engage at their inner ends the sides of rods IS! and I88. The purpose of screws 2|? and H3 is to permit block I93 and thus the yoke I8 and pivotal axis I9 to be secured at selected positions on rods I87 and I 88 between the limits of shifting, movement of these parts relative to the stationary base extension B. Screws 2 I 6 and 2 I 6a fasten the blocks I93 and I93a, respectively, to the underside of plate I94, and also serve to secure an angle member 2 IT to block I93. The outer edge 2 it of block 593a is adapted to abut clamp block I89 and limit the movement of block !93c and consequently the movement of yoke I8 and the pivot axis in the direction along supporting rods I92 and I98 toward the right as viewed in Figure 15. In like manner, the side surface 2I9, of block I93 is oriented so as to abut against the side surfaces of support. block I and the top flange of auxiliary channel member I8I to limit movement of yoke I9 and pivot axis I9 to the left as viewed in Figure 15.

In order to hold the shiftable or movable parts of the assembly I! in the position shown in Figures 14 and 15, resilient means are employed to urge block I93a into abutting contact with stationary block I99. For this purpose a rod 229 which extends under the drawing board extension B bears at one end against member 2H at 22I. Rod 229 is supported for sliding movement in a guide element 222 secured to a central plate 223 which is connected to channel members H9 and I3I of the assembly II. A resilient member such as spring 223 is anchored at one end to a stationary flange 225 fastened to channel member I39 and has its other end fastened to a lug 229 which is fixed to and movable with rod 229. An aperture in stationary flange 225 also serves to guide the movement of rod 229 in a direction parallel to rods I87 and I98.

With the above described construction of the support plate assembly II, rod 229 is movable in directions parallel to support rods I9? and I89 between the limits defined by the abutment of movable block I93a with stationary clamp block I89 at one extreme and the engagement of block I93 with the stationary block I96 at the other extreme. Movement of these parts from right to left as viewed in Figures 14 and 15 stretches spring 224 which urges rod 229 and the movable 15 parts of the assembly I to return to the position shown in Figures 14 and 15.

The purpose of providing for shifting the pivotal axis i9 is to permit simultaneous construction of stereoscopic pairs of perspective drawings. The stops on rods I8! and I88 are adjustable so as to limit the degree of movement of pivot axis -9 to an amount corresponding to the average interocular distance of an observers eyes, that is, about 2 inches. When the shiftable parts of assembly I! are in the position shown in Figures 14 and 15, points on one perspective view T, see Figures 3 and 4, may be located under guide '58 of plotting means I. When the movable parts of the assembly are shifted against the pressure of spring 225 to the inner limit of travel, points on the companion stereoscopic view T may then be located under plotting guide 3?. Thus, stereoscopic pairs of perspective drawings may be made simultaneously and conveniently.

In order to effect movement of pivot axis 49 as described above without necessitating diversion of the attention of the operator, a foot pedal generally indicated at 235, see Figure 16, is provided. The foot pedal consists of a base plate 23! and a pair of spaced brackets 232, only one of which is shown, at one end of the base plate, and another bracket 233 secured to the other end of the base plate. A pair of spaced channels 235 and 235 project upwardly from the base plate and are secured pivotally to brackets 232 on a pair or" pins 235 held by adjustable clamp means 23%. A cross bar 23'! is secured to the upper ends of channels 235 and 235 and has an aperture 238 for receiving a threaded bushing 239 to which is s cured a hollow tube .246 for guiding a wire i l-t into the pedal assembly.

A foot operated channel shaped bar it? pivotally connected to bracket 233 and has its other end connected pivotally to a clamp member 243 which is fastened to one end of a wire which extends from the foot pedal to the support plate assembly I'i. Wire 2 35 passes through a flexible conduit, not shown, and is connected at its other end to member 2ll of the assembly H by nut and bolt means 255, see Figure 14. Wire 244 extends inwardly from angle 2 l and through the flexible conduit, one end of which is attached to stationary flange 225. The flexible conduit is looped through a guide member 255 and passes down to the foot pedal 2%. Foot bar 262 is suspended above and spaced from base plate 23! by virtue of the tension on the wire 2455 caused by spring 225 of assembly I'l. When bar 242 is depressed, as by the foot of the operator, wire 244 shifts member 257' to the left as viewed in Figures 14 and 15 which results in movement of the pivot axis l s of assembly ll parallel to the picture plane and of approximately 2 inches. As will appear more fully in the description of the operation of my machine, this shift causes a corresponding movement of plotting means "i in the same direction which properly positions plotting guide Tl for the location of the selected point on the companion perspective view T.

The elevation rod 20, see Figures 14 and 15 is secured in the cylindrical head I92 by means of a locking screw 255 and extends through block 251. During assembly of the machine, yoke I8 and the cylindrical head 92 are oriented with respect to each other so that the longitudinal axes of rod and plan beam I3 are perpendicular to each other. Elevation rod 20 therefore is arranged to pivot with respect to the base 13 about shaft I96 while maintaining perpendicularity with plan beam l3 throughout the operation of the machine. The outer end of rod 25 is supported for movement over base B on wheels 252 and 2-53 .pivotally carried by support piece 251 which extends transversely of rod 25 and is adapted to be adjustably positioned therealong.

lhe rearwardly extending portion of elevation beam 22 is supported for movements transversely of and pivotally on rod 25 by a support assembly 2 I, see Figures 14 and 15. This assembly consists of a member 255 through which rod 25 passes and on which beam 22 is supported and clamps 256 and 25? on rod 25 and on opposite sides of member 255 which have screws 253a and 25m for releasably clamping same to rod 25 to permit adjustment of the position of assembly 23 along rod 20. A short flanged pin 255 is mounted on member 255 and is the element about which pivoting of beam 22 takes place. Guide members 259 and 255 extend transversely of member 255 and are laterally spaced to define a channel through which elevation beam 22 passes. Roller blocks 261 and 252 secured to guide members 25d and 250 are provided with rollers 253, 25%, 255 and 256 which roll on the sides of beam 22 to facilitate sliding movement thereof with a minimum of friction. Rollers 25? and 25% are mounted beneath guide members 259 and 250 and support the beam 22. The flange 258a on pivot element 258 overlies a portion of guide members 259 and 266 and secures same for pivotal motion with respect to member 255 and rod 29.

Support assembly 2i therefore furnishes a pivotal and sliding connection between the elevation beam 22 and rod 25 while at the same time guiding movements of the elevation beam so that its longitudinal axis crosses over the axis of rod 25 at a fixed point on rod 25 selectively spaced from the ax s it of assembly I'l.

Figure 17 shows the disposition of the cords 2t and 9? on the various parts of the machine for the purpose of causing stem assembly i to move along channel member 3 in exact response to movements of slide piece i2 along guide rods 5 I (not shown in Figure 17). Cord 96 is attached at one end to a tie block 2 8i? secured to top plate 58 of stem assembly 5 and is secured at its other end to the right side plate I75 of the slide piece i2. Between these two points of connection, the cord as passes around the periphery of pull y 92 on carriage 2 and passes between lower guide rollers I22 and 322a of swivel plate assembly 9. Cord 9; similarly is attach-ed atone end to block are on plate 53 of assembly 4 and has its other end tied to the left side plate I75 of slide piece i2. Between these two points of connection, cord 97 passes around pulley 56 on channel member 3, around pulley ti on carriage 2, between top guide rollers tilt and i2ia of the assembly 5, through aperture H5 in slide piece i2 and around pulley E55 mounted on the end of guide bars i I. When slide piece I2 moves to the right, as viewed in Figure '17 along the guide bars H in response to movements of elevation beam '22, cord 5? will be under tension and will exert a pulling force on stem assembly 4 and to move same along channel member 3 in a direction away from the carriage 2. Similarly, movements of slide piece I2 to the left will place cord 95 under tension and cause stem assembly it to movetoward the carriage 2. As heretofore mentioned the reaches of the cords 95 and 91 between pulleys 92, 9| and guide rollers I2 I, IZIa, E22, IZZa, respectively, are at all times aligned and in the same vertical plane which constitutes the picture plane.

Also, cords 95 and 9'! lie in the same vertical plane between their point of passage through rollers l2l, l2la, I22 and l22a and their connection to slide piece I2 which plane constitutes a continuation of the picture plane when pointer I6 is in the initial setting position as shown in Figure 3.

Operation To illustrate the operation of my machine in the construction of perspective drawings, it will be convenient to show the procedure for plotting point A1 on the top rear corner of the prism of which P is a plan view and S a regular elevation view, see Figures 3 and 4. In order to orient the elevation ruler 6, pointer 56 on the end of plan beam i3 is placed in the initial setting position directly under the pivot axis is of swivel plate assembly 9, see Figure 3. With pointer l6 so positioned, guide rods 1 I are parallel to the "picture plane and the axis of pivot sleeve in of slide piece i2 is aligned with the axis 18 of the swivel plate assembly and also lies in the picture plane. The elevation ruler 6 and in particular the fine wire H thereof is then moved directly over the top edge of the elevation view S on which the elevation of point A1 is located. This setting of the elevation ruler 6 is eifecteol by movement of clamp 15 along height rod M, which in turn moves slide piece 12 on rods l I and finally causes stern assembly 6 to move in response to the pullin action of either cord 96 or 91. When the Wire or hair line H of the' elevation ruler is aligned with point A1 on elevation view S, clamp I is locked in position on rod l4 and the machine is ready to plot the location of point A1 in the perspective view.

The next step consists in placing pointer it on the point A1 in the plan view P of the prism, as shown in Figure 4. This produces two distinct movements on the machine, namely, the carriage 2 is moved to the left and slide piece I 2 is moved to a new position on rods H. The perspective straight edge I also moves to the leftv along with carriage 2 and toward guide bar I in response to the movement of slide piece I 2. The position of plotting guide 18 on perspective straight edge 1 determines the location of point A1 in the perspective view which may be marked by a pencil or other marking means inserted through the V-shaped slot 82 in guide 18.

Other points on the prism whose height above the base of the prism is the same as point A1 for example, points A2, A3 and A4 may be located in the perspective view by moving pointer it over each point in the plan view P and marking the location of same in the perspective View as described above. When other points on the prism at a different elevation from point A1 are to be plotted, the pointer IE is returned to the initial setting position, clamp I5 is loosened and moved until wire H of elevation ruler 5 is aligned with position of the new point or points on the elevation view S. When this is done, the plotting procedure outlined above is followed to plot the points in the perspective view. The plotted points may be connected by means of a pencil to complete the perspective view T.

Although I have described the plotting procedure specifically as including the step of marking points under guide it, it is also possible to trace the outline of shapes lying in any one horizontal plane. This may be accomplished by tracing the outline of the plan view P for example, with pointer 16 and holding a. pencil in recess 82 of guide 18 and in contact with the surface of the paper on which the drawing is to be traced. All points at the same height or elevation may be traced in this manner, it being neces-'- sary to reset the elevation ruler 6 as described above in order to plot other points in planes at different elevations.

In order to construct stereoscopic pairs of perspective drawings, only two steps in addition to those outlined above are needed. The foot pedal 23% shown in Figure 16 and described above is located under the drawing .board B preferably on the floor and near the foot of the operator. After each point is plotted under guide :78 of the perspective plotting element 1, the foot bar 242 of pedal 23!) is depressed by the foot of the operator which causes the yoke I8 of assembly I! and the rod 29 to shift approximately 2 inches to the left as viewed in Figures 3 and 4 and parallel to the picture plane while pointer 16 remains on the particular point in plan View P which is being plotted. Since the pivotal axis of support assembly 2| represents the elevated observation point. and pivot axis IQ of support plate assembly ['1 represents the projection of the observation point in the base plane as seen by one eye, movement of axis [9 parallel to the picture plane by an amount equal to the interoculary distance of an observers eyes sets up a condition on the machine representative of the observer viewin the prism through his other eye. The physical effect of this shifting movement is to move the rearward. supports of plan beam l3 and elevation beam 22 which in turn move carriage 2 and thus the perspective plotting member I to a new position which represents the view in the picture plane seen by the other eye of the observer.

After the operator actuates pedal 239, a point in view 'I" is marked under plotting guide 11. When the pedal is released, the movable components return to their original positions under the pressure of spring 22 5 in assembly 17 and the machine is ready to plot'the next point. This procedure is followed for the plotting of each point in views T and T. The points as plotted may then be connected by a pencil, the resultant drawings constituting stereoscopic pairs of perspective drawings of the prism. It will be noted that points on drawing T are plotted at the same time that those of drawin T are plotted without diverting the attention of the operator from the drawing board. The plotting guides ii and T8 are adjustably spaced apart to effect proper spacing the stereoscopic pairs of drawings T and T.

The position of support assembly 2| for elevation beam 22 on rod Zli, that is, the radial distance between the point on rod 211 over which the longitudinal axis of elevation beam 22 extends and the pivot axis 19 of the support plate assembly I? is relative to the height of the observation point above the base'plane. In other words, the assembly 2| represents the eye of the human observer. It is often times desirable to construct perspective drawings of an object wherein the height of observation is des ignated, for example, it may be specified that a ground leve or below ground level View, an eye level view or a birds eye view of the object be drawn. For this purpose I have'con- 19 To illustrate this feature of my invention, I have shown in Figure 4 a point M on rod 29 to which, it will be assumed, assembly 2! is moved so that the longitudinal axis of elevation beam 22 crosses the axis of rod 20 at point M. With assembly 21 so positioned and the steps followed as outlined above to construct perspective drawings and/or stereoscopic pairs of perspective drawings, the stereoscopic pairs of views K and K of the prism as shown in Figure 4A will result. Since the point M on rod 29 is closer to the pivot axis 19 of assembly I! than the original and illustrated position of assembly 2! as shown in Figure 4, movement of assembly 21' to point M in effect lowers the height of observation. The perspective drawings T and T of Figure 4 may, for example, represent a birds eye view of the prism while the drawings K and K of Figure 4A may represent an eye level view of the prism. It will be understood that my machine is capable of being adjusted to different heights of observation both above and below the base plane and other than those which I have illustrated and described.

In event it is desirable to use an additional regular elevation or auxiliary elevation view S in the construction of the perspective drawing T, the auxiliary elevation ruler 8 is connected to the end of bar 5 so as to span the view S. The ruler 8 is adjusted on bar 5 so that its wire or hair line edge is aligned with a chosen reference point on view S at the same time that wire H of ruler 6 is set at the height of the same point on View S. Ruler 8 is fastened tightly to bar 5 and is thereafter used in the same manner described above in connection with ruler 6.

Another feature of my invention is that the elevation views S and S and the perspective views T and T may be oriented so that they stand in the same direction. Furthermore, the perspective views T and T as constructed according to my invention also stand in the same direction as does the plan view P. This arrangement of views is particularly convenient and helpful to the drawing machine operator by enabling him to better visualize the character of the object being drawn and to facilitate in the proper construction of perspective views.

In event it is desired to remove the drawin machine from the drawing board for storage or shipment, or otherwise, it is necessary that only four thumb screws be loosened to disengage the machine from the drawing board. These screws are guide bar clamp screws 25 that secure each end of guide bar I to the base B and screws I80 that secure the support plate assembly I! to the base extension B. There are no other clamps or screws required to secure the drawing machine to the base, which feature enables quick and convenient setup and removal of the machine.

Those skilled in the art will appreciate that various changes and modifications may be made in my invention without departing from the spirit and scope thereof. Accordingly it is to be understood that my patent is not limited to the preferred form of the invention described herein, the essential characteristics of my invention being summarized in the following claims.

I claim:

1. In a perspective drawing machine, a base, a carriage supported for rectilinear movement over said base, a plotting member carried by said carriage and movable over said base relative to said carriage, a plan beam and an elevation beam each disposed parallel to said base and each supported on laterally spaced supports for pivotal movement about a pair of common axes and rectilinear movement relative to said base, means for moving said carriage in response to pivotal movement of said plan beam, means for moving said elevation beam in response to movements of said plan beam, and means for translating movements of said elevation beam in directions transversely of said plan beam into movement of said plotting element relative to said carriage.

2. In a perspective drawing machine, a base, a carriage supported for rectilinear movement over said base, a plotting member carried by said base and movable over said base relative to said carriage, a plan beam and an elevation beam each disposed parallel to said base and each supported on laterally spaced supports for pivotal movement about a pair of common axes and rectilinear movement relative to said base, means for moving said carriage in response to pivotal movement of said plan beam, means for moving said elevation beam in response tomovements of said plan beam, means for translating movements of said elevation beam in directions transversely of said plan beam into movement of said plotting element relative to said carriage and means for maintaining fixed selected horizontal spacings between the adjacent ends, respectively, of said beams.

3. In a perspective drawing machine, a base, a carriage supported for rectilinear movement over said base, a plotting member carried by said carriage and movable over said base relative to said carriage, a plan beam and an elevation beam each disposed parallel to said base and each supported on laterally spaced supports remote from said carriage for pivotal movement about a common stationary axis and rectilinear movement relative to said base, means for moving said carriage in response to pivotal movement of said plan beam, means for moving said elevation beam in response to movements of said plan beam, means for translating movements of said plan beam in directions transversely of said plan beam into movement of said plotting element relative to said carriage, and means for simultaneously shifting the position of said supports for said beams in substantially the same direction as the path of movement of said carriage.

4. In a perspective drawing machine, a base, a carriage supported for rectilinear movement over said base, a plotting member carried by said carriage and movable over said base relative to said carriage, a plan beam and an elevation beam each disposed parallel to said base and laterally spaced from the other, separate points of support for supporting said beams for pivotal movement about a common stationary axis and rectilinear movement relative to said base, the point of support for said elevation beam being pivotally connected to and selectively horizontally spaced from the point of support for said plan beam, means for moving said carriage in response to pivotal movement of said plan beam, means for moving said elevation beam in response to movements of said plan beam, and means for translating movements of said elevation beam in directions transversely of said plan beam into movement of said plotting element relative to said carriage,

5. The machine according to claim 4which includes means for selectively horizontally spacing the ends of said beams remote from said common axis in directions perpendicular tothe longitudinal axis of said plan beam.

6. A perspective drawing machine comprising a base, a carriage supported on said base for rectilinear movement thereover, a plotting member supported for movement parallel to and perpendicular to the path of movement of said carriage, a plan beam extending parallel to said base and transversely of the path of movement of said carriage, a pivotal support for said plan beam on said base, an elevation beam, a pivotal support for said elevation beam horizontally spaced from and pivotally connected to the plan beam support, means for maintaining fixed selected horizontal spacing between said beams, a slide piece supported for movement in directions parallel to said base and transversely of said plan beam and having a pivotal and sliding connection with said elevation beam, and means for moving said plotting member relative to said carriage in response to movement of said slide piece relative to said plan beam.

7. A perspective drawing machine comprising a base, a carriage supported on said base for rectilinear movement thereover, a plotting member supported for movement parallel to and perpendicular to the path of movement of said carriage, a plan beam extending parallel to said base and transversely of the path of movement of said carriage, a pivotal support for said plan beam on said base, an elevation beam, a pivotal support for said elevation beam, means for connecting said beams comprising a rod disposed to pivot about the pivotal axis of the support for said plan beam in response to similar movement of said plan beam, the pivotal support for said elevation beam being selectively horizontally positioned on said rod, a slide iece supported for movement parallel to said base in directions transversely of said plan beam and having a pivotal and sliding connection with said elevation beam, and means for moving said plotting member relative to said carriage in response to movement of said slide piece relative to said plan beam.

8. A machine for constructing perspective drawings from regular plan and elevation views comprising a planar base on which said views are mounted, a carriage on said base and movable in a straight line thereover, a plotting element supported for movement over said base in directions parallel to and perpendicular to the path of movement of said carriage, a plan beam disposed parallel to said base, point locating means on said plan beam, a horizontally pivotal member for supporting said plan beam remote from said carriage, guide means anchored to said base, said pivotal member being mounted on said guide means and movable therealong in directions parallel to the path of movement of said carriage, means for moving said carriage in response to pivotal movements of said plan beam, an elevation beam, another horizontally pivotal member movable over said base in directions parallel to and transversely of the path of movement of said carriage and adapted to support said elevation beam, means for moving said other pivotal member in response to movement of said first named pivotal member on said guide means, means for co-ordinating movements of said beams, and means for moving said plotting element in directions parallel to and perpendicular to the path of movement of said carriage in response to movements of said plan beam.

9. A machine for constructing perspective drawings from regular plan and elevation views comprising a planar base on which said views are mounted, a carriage on said base and movable in a straight line thereover, a plotting element supported for movement over said base in directions parallel to and perpendicular to the path of movement of said carriage, a plan beam disposed parallel to said base, point locating means on said plan beam, a horizontally pivotal member for supporting said plan beam, guide means anchored to said base, said pivotal member being mounted on said guide means and movable therealong in directions parallel to the path of movement of said carriage, means for moving said carriage in response to pivotal movements of said plan beam, stops associated with said guide means to limit the movement of said plan beam support member, foot pedal means connected to said plan beam support member to actuate movement of same between the limits defined by said stops, guide means anchored to said base, said pivotal member being mounted on said guide means and movable therealong in directions parallel to the path of movement of said carriage, means for moving said carriage in response to pivotal movements of said plan beam, an elevation beam, another horizontally pivotal member movable over said base and adapted to support said elevation beam, means for co-ordinating movements of said pivotal members, means for co-ordinating movements of said beam, and means for moving said plotting element in directions parallel to and perpendicular to the path of movement of said carriage in response to movements of said plan beam.

10. The machine according to claim 9 in which said plotting element has a pair of laterally spaced marking means for plotting points on stereoscopic pairs of perspective drawings, one of said marking means defining the location of points on one of said perspective drawings when said plan beam support member is positioned at one limit of movement and the other of said marking means defining the location of points of the other perspective drawing when said plan beam support member is positioned at the other of said limits of movement.

11. In a machine of the character described, a planar base, a carriage adapted to move in a straight line over said base, a plotting element, means connecting said plotting element to said carriage for guiding movement of said plotting element in directions parallel to and perpendicular to the path of movement of said carriage, a plan beam, means for supporting said plan beam for pivotal and rectilinear movements relative to said base, point locating means on one end of said plan beam, an elevation beam, means for supporting said elevation beam for pivotal and rectilinear movements relative to said base, means connecting said plan beam to said elevation beam, a guide member carried by said carriage and extending therefrom parallel to said base and perpendicular to the longitudinal axis of said plan beam, a slide piece on said guide member and adapted to move therealong, said slide piece having pivotal and sliding connection with said elevation beam, and means for moving said plotting element in response to movements of said slide piece along said guide member.

12. The machine according to claim 11 in which said guide member and said carriage have pulley means, said plotting element movement means including cord means connected to said slide piece and said plotting element and engaging said pulley means and efiective to move said plotting element in directions perpendicular to the path of movement of said carriage in response to said movement of the slide piece along said guide member.

13. The machine according to claim 12 which includes means for supporting said plan beam for pivotal and transverse movements relative to said carriage, said cord means being disposed to pass through the axis of pivoting of said plan beam relative to said carriage. 4

14. The machine according to claim 11 which includes a swivel plate mounted on said carriage and adapted to pivot relative to said carriage in a plane parallel to said base, means on said swivel plate to support said plan beam for movement transversely of said plate, and a position plate fixed to said base having a recess therein alignedwith the pivotal axis of said swivel plate, said point locating means on said plan beam being positionable in said recess.

15. A machine for constructing perspective drawings from regular plan and regular elevation views, comprising a base, a carriage mounted on said base for movement thereover in a straight line, a plan beam and an elevation beam each supported for simultaneous movement parallel to said base, point locating means on said plan beam for locating points on said plan View, means for oo-ordinating movements of said plan beam and elevation beam, a plotting element, an elevation ruler disposed to span said elevation view, said element and said ruler being disposed to extend substantially parallel to the direction of movement of said carriage an elongated rigid member carried by said carriage and adapted to move in directions perpendicular to the path of movement of said carriage, means for connecting said plotting element and said elevation ruler to said rigid member, and means for moving said rigid member relative to said carriage in response to movements of said plan beam and said elevation beam.

16. A perspective drawing machine comprising a base, a carriage supported for straight line movement over said base, a bar supported on said carriage for movement therewith and relative thereto in directions perpendicular to the path of movement of said carriage, a perspective plotting element connected to said bar and extending therefrom parallel to the path of movement of said carriage, an elevation ruler similarly connected to said bar, a plan beam extending parallel to the plane of said base transversely of the path of movement of said carriage a pivotal support for supporting said plan beam in pivotal and rectilinear movements relative to said base, an element pivotally connected to said carriage and adapted to pivot in a plane parallel to said base, said plan beam being engageable With said element and movable transversely thereof, an elevation beam extending parallel to the plane of said base and disposed in substantially side by side relation with said plan beam, a pivotal support for said elevation beam, a rod connected to the ivotal support for said plan beam and extending therefrom perpendicular to the longitudinal axis of said plan beam, said pivotal support for said elevation beam being releasably connected to said rod, another rod connected to the end of said plan beam remote from the pivotal support therefor and extending from said plan beam in a direction perpendicular to the longitudinal axis thereof, clamp means releasably clamped on said another rod and pivotally connected to the end of said elevation beam, guide rod means connected to said pivotal carriage element and extending therefrom in a direction perpendicular to the longitudinal axis of said plan beam, a slide piece carried by said guide rod means and mov able therealong, said slide piece having pivotal and sliding connection with said elevation beam, and cord means connected to said slide piece for moving said bar in directions perpendicular to the path of movement of said carriage.

17. A machine for constructing perspective drawings from regular plan and regular elevation views, comprising a base, a carriage mounted on said base for movement thereover in a straight line, a plan beam and an elevation beam each supported for pivotal and rectilinear movement parallel to said base, an anchor member secured to said base, said pivotal support for said plan beam being slidably connected to said anchor member and movable thereover parallel to the path of movement of said carriage, foot pedal means connected to said plan beam pivotal sup-- port to actuate movement of same, point locating means on said plan beam for locating points on said plan view, means for oo-ordinating move-- ments of said plan beam and elevation beam, a plotting element, an elevation ruler disposed to span said elevation view, an elongated rigid member carried by said carriage and adapted to move in direction perpendicular to the path of movement of said carriage, means for connecting said plotting element and said elevation ruler to said rigid member, and means for moving said rigid member relative to said carriage in response to movements of said plan beam and said elevation beam.

18. The machine according to claim 3 in which said last named means comprises guide elements supporting said plan beam support for limited transverse movement parallel to the path of movement of said carriage, means to limit said transverse movement of said plan beam support, and means to actuate movement of said plan beam support between the limits of said transverse movement.

19. The machine according to claim 18 in which said plotting member comprises an elongated bar extending parallel to said base and to the path of movement of said carriage, a pair of adjustably spaced plotting guides on said plotting member, said guides locating the position of plot points on stereoscopic pairs of perspective drawings when said plan beam support is located at the respective limits of its movement.

20. The apparatus according to claim 9 which includes a flexible cable'connected at one end to said pedal means and at the other end to said plan beam support member whereby actuation of said pedal will move said element in one direction, and spring means connected to saidbase and said support member urging the latter to move in the opposite direction.

21. A drawing machine for making perspective drawings from regular plan and elevation views by reproducing in perspective the image of a selected three dimensional object referred to a picture plane, comprising a base lying in plane perpendicular to said picture plane, an elongated guide bar fastened to said base parallel to and spaced from said picture plane, a carriage supported for movement on said guide bar, a plan beam plvotally supported at one end on said base and having pivotal and sliding connection with said carriage whereby pivoting of the beam about said one end will cause said carriage to move along said guide bar, the pivotal connection between said plan beam and said carriage lying in said pictureplane, a point locating element on the other end of said plan beam for selecting points on the plan view tobe plotted, said plan beam being movable to position a said point 10- cating element in said picture plane whereby to facilitate plotting of points lying in said picture plane, a plotting member and means to move said plotting member in response to point locating movements of said plan beam.

22. The machine according to claim 21 in which the pivotal connection between said plan beam and said carriage is spaced above said base, said plan beam being laterally offset from both the axes of pivotal connection of same to said carriage and to said base, said point locating element extending outwardly from said plan beam a distance equal to the offset of said plan beam from said axes whereby to facilitate positioning same under said pivotal connection and in the picture plane.

23. In a machine of the character described, a planar base, a carriage adapted to move in a straight line over said base, a plotting element, an elevation ruler, means connecting said plotting element and said elevation ruler to said carriage for guiding movement of same in directions parallel to and perpendicular to the path of movement of said carriage, a plan beam, means for supporting said plan beam for movements parallel to said base, point locating means on one end of said plan beam, an elevation beam, means for supporting said elevation beam for movements parallel to said base, means connecting said plan beam to said elevation beam, a guide member carried by said carriage and extending therefrom parallel to said base and perpendicular to the longitudinal axis of said plan beam, a slide piece movable on said guide member, said slide piece having pivotal and sliding connection with said elevation beam, and means for moving said plotting element and said elevation ruler normal to the direction of carriage movement in response to movements of said slide piece along said guide member.

OLIVER M. STONE.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 406,083 Brix July 2, 1889 1,986,625 De Lorenzi Jan. 1, 1935 2,442,117 Davis May 25, 1948

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