US 3808691 A
The invention presents apparatus for drawing ellipses. A center pivot leg and an inscribing leg are pivotally connected intermediate their lengths. The inscribing leg rotates as the instrument is rotated, to draw an ellipse. The upper end of the center pivot leg is rotated in planetary motion around the axis of the instrument as the inscribing leg is rotated, causing the lower end of the center pivot leg to pivotally move to alter the length of the radius vector of the ellipse as the ellipse is drawn. The angularity between the center leg and the inscribing leg is altered during rotation so that an ellipse is drawn.
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Description (OCR text may contain errors)
United States Patent 1 Chase [.54] APPARATUS FOR DRAWING ELLIPSES  Inventor: Russell C. Chase, 6626 Guhn Rd.,
' Houston, Tex. 77040  Filed: Nov. 29, 1972  Appl. No.: 310,464
 US. Cl. 33/30 G 245,774 4/1912 Germany 33/30 A Primary Examiner-Harry N. Haroian A Attorney, Agent, or Firm-Carl B. Fox, Jr.
. ABSTRACT The invention presents apparatus for drawing ellipses. A center pivot leg and an inscribing leg are pivotally connected intermediate their lengths. The inscribing leg rotates as the instrument is rotated, to draw an ellipse. The upper end of the center pivot leg is rotated in planetary motion around the axis of the instrument as the inscribing leg is rotated, causing the lower end of the center pivot leg to pivotally move to alter the length of the radius vector of the ellipse as the ellipse is drawn. The angularity between the center leg and the inscribing leg is altered during rotation so that an ellipse is drawn.
10 Claims, 4 Drawing Figures May 7, 1974- PATENTEUIAY H914 SHUT 2 BF 3 PATENTEUNAY 1 m4 SHEET 3 OF 3 1 APPARATUS FOR DRAWING ELLIPSES SUMMARY OF THE INVENTION The drawing ofellipses has always been a problem to draftsmen and artists. Ellipses may be constructed by tedious methods, but because this is a time consuming and disagreeable task, most draftsmen and artists when faced with drawing ellipses use simpler constructions giving only approximate ellipses or use drawing tools or guides which permit drawing of ellipses only approximating the desired ellipical shapes to be drawn. The apparatus herein disclosed is useful in drawing accurate ellipses. The major and minor axes of the ellipses may be altered, as well as the sizes of the ellipses, so that within the range of the apparatus asto size completely accurate ellipses of any proportions may be drawn. The apparatus is very accurate in use and repeatable results are obtained.
The apparatus is simple in operation and may be used by any person desiring to draw ellipses.
Other objects and advantages of the invention will appear from the following description of a preferred embodiment, reference during the description being made to the accompanying drawings.
BRIEF DESCRIPTIONS OF THE DRAWINGS FIG. 1 is a lower side perspective view of an apparatus of preferred form according to the invention.
FIG. 2 is a vertical cross sectional view taken along the vertical axis of the apparatus shown in FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENT Referring first to FIG. I. of the drawings, an upper body or housing has therebelow a rotating body or housing 12, into the lower side of which is disposed a second rotating body or housing 14. Elements 10, 12 and 14 are of circular cross section and are coaxially disposed.
Housing-l4 has connected therebelow an inscribing leg 15 pivotally connected between lugs 17, 18 depending from the outer edge of the lower side of body 14. Leg 15 is pivotal toward and away from the center or axis of body 14. A threaded center pivot leg 19 is radially movably connected (as will be later shown) at the underside of body 14, and its lower end is pivotally connectedto circular plate 21 which is supported by three legs 22-24 affixed-to the lower side' of body 14. The lower end of center pivot leg 19 is held at theaxis of bodies 10, 12 and 14. I
Inscribing leg 15 and center pivot leg 19 are each pivotally connected intermediate their lengths to opposite A tubular anchor leg 32 is pivotally connected to body 10 by a pin extending-between brackets 34, 35 vertically affixed to the side of body 10. Leg 32 is angularly movable toward and away from the center axis of the apparatus. Leg 32 has telescopically engaged into its lower end a lower anchor leg 36 having a pointed tip 37 affixed to its lower end. The lower end of anchor leg 36 is slightly inturned so that when the anchor legs are extended to one side of the apparatus the tip 37 will be directed in a downward direction. Anchor leg 36 is extendable out of and retractable into leg 32 so that the total anchor leg length may be adjusted. Legs 32 and 36 are of square cross section as shown, or are otherwise fixed together against mutual rotation, in order that tip-37 will remain pointed downwardly.
Referring now also to the other figures of the drawings, body 10 has a concentric circular recess 40 at its lower side. A circular plate 41 is disposed therein and I hasan upwardly projecting concentric stem or shaft 43 which is disposed through an opening concentrically v above recess 40. Bearing 44 is disposed in the opening around shaft 43. A turning knob 46is fixed on shaft 43 by set screw 47.'Rotation of knob 46 rotates plate 41.
Body 12 has a concentric circular recess 49 at its lower side. Body 12 is connected to plate 41 by screws 51 (see FIGS. 2 and 4) .which extend upwardly through openings through a spacer member 52 and are screwed 'into tapped openings in plate 41. Therefore, body 12 rotates when knob 46 and plate 41 are rotated. A ring gear 54 having internal teeth is fixed in place in the lower part of recess 40 beneath plate 41. Ring gear 54 does not rotate with plate 41. A stem or shaft 55 is journaled through bearing 56, fixed in an excentric opening through plate 41, and bearing57, fixed in an opening through the upper-part of body 12 above recess 49.'Between these bearings, shaft 55 carries a circulr gear 59 which is engaged with ring gear 54. Gear 54 is twice the diameter of gear 59, and has twice as many teeth as gear 59.
Spacer 52 is of generally crescent shape and occupies almost all of the space within ring gear 54 not occupied by gear 59. When plate 41 is rotated by rotation of knob46, gear '59 is rotated around the interior of gear 54. Gear 59 moves in epicyclic or planetary movement around the interior of gear 54.
Shaft 55 is integrally formed with .an enlarged coricentric cylindrical body 61 at its lower end. Body 61 ends of connection bar 26. The angularity between legs l5 and 19 may change, but the spacing therebetween at the location of connection bar 26 remains constant.
A downwardly pointed tip element 27 is affixed to plate 21 coaxially with bodies I0, 12 and I4. Inscribing ment 27. r
has a lateral bore 62 therethrough which is enlarged at its outer ends and reduced at 63. A screw 65 held in place in bore 62 by press-fitted ring 66 is threaded through an element 68 disposed in the enlarged end of bore to the lefthand side in FIG. 2. Rotation of screw 65 moves element 68 axially of bore 62.
Cylinder 61 is disposed within an upper concentric cylindricalrecess 70 of body 14. Recess 70 has a vertical side slot flat the position of each of three screw 72 which connect legs 22, 23, 24 to the underside of body 14.
1 Body 14 is rotatably connected to body 12 by ring 74 and'steel bearing balls 75 disposed in V-shaped groove 76 around body 14. Plural screws 78 connect ring 74 to body 12. The outer sides of balls 75 are disposed between upwardly and downwardly facing bevels of ring I 74 and body 12. Body 14 is rotatable with respect to body 12.
The lower wall of body 14 has a slot 81 therethrough which is of concave V-shaped cross section at its sides. A slide element 83 having convex V-shaped sides is disposed in slot 81. Element 68 has downwardly extending integral shaft 85 threaded at its lower end which is movable longitudinally in a slot along the bottom of bore 62. A bushing 86 press fitted in a hole through slide 83 surrounds sleeve 87 disposed slidably around shaft 85. A nut 88 isscrewed onto the lower end of shaft 85. When nut 88 is tightened, sleeve 87 is jammed between body 61 and nut 88, and elements 68, 85 are firmly locked in place. Center leg 19 has a flange 91 around its upper end and thereabove has a ball formation 92 which is closely yet movably disposed in the unthreaded lower end of the bore through nut 88. At the lower end of leg 19 there is a ball formation 94 which is closely yet movably received in bore. 95 of tip element 27. A compression spring in bore 95 biases leg 19 upwardly.
Planetary movements of shaft 85 causes 'rotationof body 14, shaft pressure acting against the sides of slot 81 through slide 83.
Body .14 has an opening or hole 97 through its side- 59, and it is necessary to rotate bodies 14 and 61 until screw 65appears through opening 97 in order to adjust the position of element 68 by rotation of screw 65.
. The lower ends of legs 22-24 are connected to plate 21 by screws 99. Leg 19 is mounted pivotally at its upper and lower ends at ball formations 92, 94 sothat the angle of leg 19 may be adjusted by movements of element 68, the slide element 83 sliding in slot 81 as element 68 is moved toward or away from the central axis of the apparatus.
Boss 29 is of spliticonstruction and the two vertical halves are held together by screws 103, 104 to clamp pen or pencil 30 and the lower end of leg 15 therebetween in suitable recesses between the boss halves.
At the upper end of leg 15, the leg is reduced at 106 and is press-fitted into an opening in the lower crossbar of yoke 107.-Yoke 107 is connected for pivotal movement to lug elements 17, 18. Anchor leg 36 has a finger grip elment 110 around its lower end immediately above tip 37. I
Connector bar 26 is slotted at each of its ends, the end of each slot being beveled as shown in the drawmgs. threaded sleeve 114 which is engaged with the threads of leg 19. Slot 115 is pivotally pinned to collar 116 slidably disposed around leg 15. Collar 116 has a lower flange 117 through'which set screw 118 is radially threaded to set collar 116 and bar 26 in proper position. The positioning of bar 26 longitudinally of leg 19 is accomplished by rotation of the leg causing movepencil 30.sh0uld be at the same spot as the tip 27. This,
of course, is impossible as the pen or pencil tip and tip 27 cannot occupy the same point.
Slot 112 is pivotally connected to interiorly.
In using the instrument to draw an ellipse, the center point or tip 27 is placed at the position of the center of the ellipse. The lower anchor leg 36 isdrawn out of upper leg 32 to a distance well beyond the limits, of the ellipse to be drawn; to allow for movement of leg 15 thereunder. The tip 37 is punchedinto the surface to anchor b'ody 10 against rotation.
The anchor legmust be aligned with the. minor axis of the ellipses drawn with the apparatus. This requires timing of the relative positions of elements 10, 34, 54, 59 and 61, for proper dispositions as ellipses are drawn. All of these parts must be very accurately located and keyed or otherwise affixed, in relation one to the others, in order to accomplish this result.
The size of the ellipse is determined by the position of bar 26. When bar' 26 is moved upwardly by loosening screw 118 and rotating leg 19 within sleeve 114, the ellipse is made larger, and when bar 26 is moved downwardly the ellipse is made smaller. The ratio between the minor and major axes of the ellipse is adjusted by movement of element 68 by rotation of screw 65. With both tips 27 and 37 anchored .into'the surface as described, knob is rotated by hand and pen or pencil 30 inscribes the ellipse.
Rotation of gear 59 and connected element 61 within bodies 12, 14 causes the upper end of leg 19 to move toward and away from the upper. end of leg 15 twice during one traverse around the ellipse.
While a preferred embodiment of the apparatus has been shown in the drawings and described, many modivertically disposed inscribing leg means having downwardly directed drawing means at its lower end, vertically disposed center leg means having a downwardly directed pivot point means at its lower end, means for fixing the lower end of said center leg means and said pivot point means at the central axis of said apparatus, 1
connector means fixing the spacing between said inscribing leg means and said center leg means intermediate their lengths, rotating means for rotating said inscribing leg means around said central axis of the apparatus to inscribe a circumscribing line therearound, an axis adjustment means for continuously varying the spacing between the upper ends of said inscribing leg means and said center leg means'while said circumscribing line is being inscribed whereby the spacing between the lower ends of said inscribing leg means and said center leg means is continuously varied whereby said circumscribing line is in the form of an ellipse.
2. The combination of claim 1, said axis adjustment means comprising means for moving the upper end of saidv center leg means in planetary motion around the center axis of the apparatus while said in'scribing leg means is rotated around said central axis of the apparatus.
3. The combination of claim 2, said apparatus-including first body means, an internal ring gear supported by said first body means, a planetary gear engaged within said ring gear, anchor means for holding said first body means in stationary position against rotation, second body means disposed below said first body means,
means for rotating said planetary gear around the inner periphery of said ring gear and for simultaneously rotating said second body means, third body means rotatably supported by said second body means, the upper end of said inscribing leg being eccentrically pivotally connected to said third body means, the upper end of said center leg being eccentrically pivotally-connected to said planetary gear and extending downwardly through a radial slot of said third body means, said third body means and said inscribing leg being rotated by planetary motion of said center leg acting against a side of said radial slot of said third body means.
4. The combination of claim 3, said anchor means comprising anchor leg means radially pivotally connected to said first body means having surface engagement means at its lower end. 7
5. The combination of claim 4, said connector means comprising a horizontal bar pivotally connected at one of its ends to said center leg and at the other end to said inscribing leg, said pivotal connections to said legs being vertically adjustable along the lengths of said legs to adjust the size of the ellipse inscribed by the apparatus.
6. The combination of claim 5, said axis adjustment means including means for adjusting the eccentricity of said connection of the upper end of said center leg to said planetary gear to change the ratio of the major and minor axes of the ellipse drawn by said apparatus.
7. The combination of claim 6, said ring gear having twice as many teeth as said planetary gear.
8. The combination of claim 2, the upper end of said center leg being rotated at twice the rotational speed of said inscribing leg means around said central axis of the apparatus, the axis of rotation of the upper end of said center leg being disposed halfway between said central axis of the apparatus and the upper end of said inscribing leg.
9. The combination of claim 1, the size of the ellipse inscribed being adjustable by adjusting the position of said connector means along'the lengths of said legs.
10. The combination of claim 1, the ratio between the major and minor axes of the ellipse inscribed being adjustable by adjustment of the spacing range through which the spacing between the-upper ends of said inscribingand center legs is varied by said axis adjustment means.