US2879596A - Ellipsograph - Google Patents

Description

Mach 31, 1959 H. A. KROENLEIN 6 ELLIPSOGRAPH Filed Dec. 28, 1954 3 mvENTOR HSMZYA. AEOEA/LEW BYOZVMM ATTORNEY Uited States Patent ELLIPSOG RAPH Henry A. Kroenlein, Los Angeles, Calif. Application December 28, 1954, Serial No. 477,963

1 Claim. or. 33-31 The present invention relates to improvements in geometrical instruments, and more particularly to improve ments in ellipsographs.

Heretofore, the art has soughtto provide devices of this type which would be easy to assemble and adjust to the conditions of operation, would be easy to orient precisely with regard to the surface on which the geometrical figure was to be drawn, and would function smoothly and readily in operation. In various efforts to provide devices of this character having these desirable features, it has been proposed to construct ellipsographs having a scriber beam guided by a pair of guide mem bers disposed at right angles toeach other after the manner of the major and minor axes of the ellipse to be drawn. However, it was found in practice that devices having such a construction were difficult to operate due to the friction between the moving parts and would often stick or bind in use. In an effort to remedy this difficulty, the working parts were loosened; but the resulting play or lost motion rendered the devices inaccurate. In an effort to mount the scriber beam firmly to the guide means, it was proposed to clamp it or bolt it to sliding guide members; but a device constructedaccording to this principle was diflicult to assemble. Moreover, in a device having the scriber means clamped to the guide means, it was found that the marker or scriber did not properly contact the surface on which the geometrical figure was to be drawn, but tended to ride above that surface or bear too heavily upon that surface. Finallyfin an effort to orient an ellipsograph nicely with regard to the major and minor axes of the ellipse to be drawn, it was proposed to provide indicator lines on the base of the ellipsograph disposed at right angles to each other, which lines could be laid over the respective axes of the ellipse to orient the instrument. However, it was found that in practice such indicia were difiicult to place precisely with regard tothe axes, with the result that the ellipsograph was frequently misaligned in use. Although many attempts were made to overcome the foregoing difiiculties and other disadvantages, none, as far as I-am aware, wasentirelysuccessful when carried into practice commercially on an industrial scale.

Accordingly, it is an object of the present invention to provide an ellipsograph in which frictional forces tending toward misalignment of the scriber will be reduced to a minimum.

Another object of the invention is to provide an ellipsographwhich will be easy to assemble and disassemble.

The invention also contemplates providing an ellipsograph in which the marker or scriber will readily adjust to the surface on which the ellipse is to be drawn so as tobear on that surface with the desired pressure at all times.

A still further object of the; invention is the provision of an ellipsograph having locator means for orienting it relative to the axes of the ellipse to be drawn, with ease and precision.

Finally, it is an object of the present invention to provide an ellipsograph which will be simple and inexpensive in construction, and rugged, durable and accurate in operation.

Other objects and advantages will become apparent from the following description taken in conjunction with the accompanying drawings, in which:

Figure 1 is a perspective view of an ellipsograph according to my invention;

Figure 2 is an isometric exploded detail view of a portion of the ellipsograph shown in Figure 1;.

Figure 3 is a plan view of a fragment of an ellipsograph according to my invention, showing the locator means in various adjusted positions; and

Figure ,4 is a front elevational view of an ellipsograph according to the invention.

Referring now to the drawings in greater detail, I have shown in perspective in Figure 1 an ellipsograph indicated generally at 1, comprising a base member 3 which may desirably be of a transparent plastic carrying at its forward edge a pair of upstanding stanchions 5 which bear between them a round bar 7 spaced above and parallel to base member 3. Spaced rearwardly of b arf7 is a pair of fixed posts 9 and 11 upstandingfrom base member 3 and serving as fixed axes for a pair of links 13 and 15 pivotally mounted on the upper ends of the posts.

i At their. outer endsylinks 13 and 15 are pivotally connectedat spaced points to a superposed bar'17 which at its outer end carries upright pin 19 lying beyond the points of pivotal connection of bar 17 to links 13 and 15.

Mounted slidably and rotatably on round bar 7 is a collar 21, perhaps best shown in Figure 2. Collar 21 will be seen to be of generally tubular form having an interior surface complementary to the outer cylindrical surface of round bar 7 to permit easy sliding therealong and rotation therea-bout. Collar 21 is provided with a central offset portion 23 which extends toone side centr'allythereof and carriers pin 25 which willbe upright when the ellipsograph isin use. k

A scriber beam 27 comprising a pair of spaced apart round bars includes a marking end 31 comprising a collar 33 having a thumb screw 35 screW-threadedly extending therethrough for the reception and retention of marking device 37, which may be in the form of a pencil or pen or stylus or other marking implement. Slidably mountedon the two round bars comprising scriber beam 27 is a first slide block 39 provided with four holes therethrough: two for the reception of the two bars comprising scriber beam 27, a round vertical hole 41 for the reception of round pin 25 when in upright position, and a laterally disposed hole for the screw-threaded reception of thumb screw 43 whichselectively locks slide block 39 to aldesired position along scriber beam 27. Rearwardly of the" first slide block with regard to the marking device is a second slide block 45 carried on scriber beam 27- for sliding movement along the two round bars through a pair 'of holes in this slide block and having a round vertical hole 47 for the reception of round pin 19 and a The ellipsograph of the invention is also provided with indicia beam for locating it relative'to the major and minor axes of the ellipse to be drawn, comprising a beveled straight edge 51 adapted to be laid exactly along the major axis of the ellipse and recessed as at 52. Inwardly of recess 52in base member 3 is a hole 53 adapted to overlie the minor axis of the ellipseto be drawn. As best seen in Figure 3, a lever 55' is pivoted at 57 to base member 3 and carries at its outer end a locator pin 59 which extends below the level of the lower surface of base member 3, as seen in Figure 4.

It should be particularly noted that pivot 57, hole 53 and post 9 are in alignment and all overlie the minor axis of the ellipse to be drawn. It should also be noted that straight edge 51 and pin 25 are in vertical alignment and both overlie the major axis of the ellipse to be drawn. To this end, the axis of pin 25 is spaced outwardly from the axis of collar 21 the same distance as the axis of rod 7 is spaced inward from straight edge 51. It should also be noted, as best seen in Figure 4, that pin 25 is substantially longer than pin 19 and terminates downward at a lower point than does pin 19. It should also be noted that pins 19 and 25 terminate upward in a common horizontal plane.

The ellipsograph according to my invention may be assembled as follows: A marking device 37 may be inserted in collar 33 and thumb screw 35 turned in to lock it in place. Pin 25 may then be turned into vertical position about bar 7 and pins 19 and 25 inserted in holes 47 and 41, respectively.

The device of my invention may be used as follows: After having drawn the two axes of the ellipse and indicated the desired major and minor radii, locator pin 59 may be pricked into the surface on which the ellipse is to be drawn at the intersection of the two axes. The device may be roughly aligned by lining up the major axis and straight edge 51; but fine alignment is made by swinging lever 55 back and forth about pivot 57 and locator pin 59. Since 59 remains fixed at the intersection of the axes, it will be seen that swinging movement of lever 55 tends to move the ellipsograph back and forth, so that hole 53 will move from one side to another of the minor axis. At the same time, straight edge 51 will undergo a slight movement relative to the major axis. When the ellipsograph is nicely oriented, thumb screws 43 and 49 may be loosened so that scriber beam 27 is free to move in slide blocks 39 and 45. The scriber beam may then beturned parallel to the major axis and, marking device 37 set on themark for the major radius and thumb screw 49 tightened. The scriber beam may then be turned 90 degrees and marking device 37 set on the mark for the minor radius and thumb screw 43 tightened. One-half of the ellipse may then be drawn, the instrument swung 180 degrees about the locator pin 59, and the other half of the ellipse drawn. It will be appreciated that during the drawing of the ellipse the pin 19 will move in a vertical plane containing the line of the minor axis, which plane also contains the center of hole 53 and the axis of post 9.

It will thus be seen that I have provided an ellipsograph in which friction is reduced to a minimum. Inasmucli as rectilinear sliding movement occurs at only one point in my ellipsograph, along bar 7, there is no opportunity for rectilinear sliding surfaces disposed at angles to each other to cause the device to stick orbind.

It will also be seen that I have provided an ellipsograph that is extremely easy to assemble and disassemble. It is necessary merely to slip scriber beam 27 over the pins 19 and 25. Tothis end, it will be noted that pin 25 is rotatable about bar 7, but that the axes of pin 25 and bar 7 are skew. Thus, the offset afforded by portion 23 insures that when pin 25 is manipulated for insertion into hole 41, any lateral movement of the upper end of the pin will be accompanied by a much smaller angular displacement than if the axis of pin 25 intersected the axis of bar 7 and pin 25 were mounted radially relative to bar 7. Thus, pin 25 may be manipulated without substantially altering its angle relative to hole 41, with the result that it may be inserted much more easily in hole 41. v

It will also be seen that I have provided an ellipse graph which can be easily located precisely with respect to theaxes of ellipse to be drawn. It was heretofore necessary to attempt bodily to skid the ellipsographs 6f the prior art into position with their indicia lines exactly' overlying the axes of the ellipse to be drawn. However, it will be seen that by manipulation of lever 55, which in this instance functions as a second-class lever, regulated movements of the lever produce fine adjustment of the ellipsograph relative to the axes, and that in the case of hole 53, it is a good deal easier to center a line in an oscillating hole than to determine when two lines appear to overlie.

It will also be seen that I have provided an ellipsograph in which the pressure with which marking device 37 bears on the surface on which the ellipse is to be drawn, is nicely regulated. As best seen in Figure 4, scriber beam 27 rests on the upper part of bar 17 through slide block 45. Pin 25 extends substantially farther down than pin 19, so that slide block 39 thereabout never rests on portion 23 but always slides up and down on the pin. There will inevitably be a slight amount of play between pin 19 and block 45, with the result that marking end 31 enjoys a slight vertical adjustability, as seen indotted lines in Figure 4 at the left thereof, the dotted lines to the right thereof being omitted for the sake of clarity.

Finally, it will be seen that I have provided an ellipsograph which is easy and inexpensive to manufacture and assemble and is sturdy, durable and accurate in operation.

Although the present invention has been described in conjunction with preferred embodiments, it is to be understood that modifications and variations may be resorted to without departing from the spirit and scope of the invention, as those skilled in the art will readily understand. Such modifications and variations are considered to be within the purview and scope of the invention and appended claim.

, I claim:

7 An ellipsograph comprising a horizontal planar base having a reference edge alignable with the major axis of the ellipse to be drawn, a scriber beam, guide means, means affixed to said base parallel to said edge pivotally mounting said scriber beam on said guide means, said pivotal mounting means being movable rectilinearly along said guide means, locator means adjustably positionable on said base at the intersection of the major and minor axes of the ellipse to be drawn, a pair of links mounted for rotation on said base about spaced axes fixed relative to said guide means, and a bar pivotally connected to each said link at a point spaced from its respective axis and to said scriber beam at a third point spaced from said pivotal mounting means, one of said spaced axes defining with said locator means a first line perpendicular to the line of rectilinear movement of said pivotal mounting means along said guide means coincident with the minoraxis of the ellipse to be drawn, reference means (in said base on said first line to align said first line and the minor axis, said third point moving in a vertical plane containing said first line.

References Cited in the file of this patent OTHER REFERENCES Ke'ow'n and Faiie's: Mechanism, published by Me- Gawain Book 30., me, New York, 1931, pages 11-12.

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