US2670540A - Ellipsograph - Google Patents

Description

March 2, 1954 RANDLES 2,670,540

ELLIPSOGRAPH Filed Dec. 29, 1952 2 Sheets-Sheet l INVENTOR.

Arthur E Rand/es ATTORNEY March 2, 1954 A E. RANDLES I 2,670,540

ELLIPSOGRAPH Filed Dec. 29, 1952 2 Sheets-Shet 2 INVENTOR. Arfhur E. Rand/es A TTORNEY Patented Mar. 2, 1954 ED" S-T ES BAT E'N-T Fl CE ELLIPSOGRAPH Arthur-E..Randles;Redwood City, Calif.

Application December 29, 195-2; Serial No.v328,422-

(Ola 33-31) 1 2 Claims. 1,

This invention relates. toimprovements in ellipsographs;

The invention provides an improved design suited for manufacture of the instrument from standard round and flat stock with the minimum of machining operations. The improved instru ment'is simple to assemble and adjust, easy to pre-set for ellipses of various :sizes'and operates smoothlydue to freedom from binding. of, and

undue friction between, its operating parts, a

disadvantage inherentiin many forms of "conventional ellipsographs. The new design of the instrument permits the drawing of very accurate figures, up: to sizes. which are quite large considering the compact size of the instrumentand affords a wide-rangeoiadjustment; In one ex tremei-adjustmentt circles can lee-drawn, in another extreme: adjustment the instrument drawsrstraight lines; In intermediate positions the instrument draws ellipses, the'long and short axis: of which, may be conveniently pre-set by a rather simple adjustment .on' the instrument.-.

'I'heseand various other objects," features- .and advantages of the invention will appear more fullyfrom the detailed description which'zfollows, accompanied by drawings, showing tor the Fig. 1 is a perspective view of-the-instrument.

in operating position;

Fig, 2 is a perspective view of the instrument turned upside down; and

Fig. 3 is a perspective detailed viewof preferred form of mounting for the-scriber.

In the following description, and in the claims, various details will be identified by specific names for convenience. The names, however, are intended to be as generic in their application as the art will permit. Among the terms employed, the element for drawing the figure proper is collectively referredto as a scriber or scribing means, it being nderstood thattit may be; a. penciLpen, stylus, engraving tool, or, any other meansusediiora similarpurpose.

In 1 the drawings accompanying; and formmg part of, this specification, certain specific-disclosure of. the-invention ismade for the purpose of e explanation ,of, broader aspects of. the. inven-rtion, but it-isunderstoodthat the details may be modified, in variousrespects, withoutdeparturefrorntheaprinciples of thepinvention, and that theinvention may be applied to other structures than the onespeci-iically shown Referring to..thedrawings,-v the ellipsograph comprises a frame Ll. The frameproper. is preferably constructed from a pair of parallel bars I! and. I3, substantially of-- o-shapewhen viewed inelevaticn, Theends: it, l5, l6 and I1 oftheG constitutelegsand are provideda'with the usual point insertsalB, 19,10 arid-21;.heldin place by-set-screws-22,23, 24 and ,25.- The-bight portions: 26. and, of the c are substantially straight and 0 parallel and constitute a pair of tracks-28 and 29;

A paireof parallel second: bars:- 30:.and 3| ex.- tend ibetween. the-bight portions M5. and. 2! of the 0 barslflrand l3. The-second-barsare-preferabl-y threaded. at the-ends, screwed into cor- -responding;'tappedholesttz;in thebars l2. and

I3. Lock nuts visible at 33 and 34 serve tortighten the connection 1 between the secondibars 30, s llandtheifirst bars im-and. IS. The secondbars Cali-and .3! extend at-right anglesto the first bars lZ-and I3 and.alsorconstituteapair of. tracks for. arpurpose which .will prese-ntlybeedescribed.

Afirst carriage-e35 is movable-along the tracks 281mm 292:0!1the-instrument.- This, carriageis preferably substantially I-shaped. The ends-s of the. I136 and; 31 are blocks which straddlethe bars]! and: I3 andare slida-bleealong; the tracks 28 and .29. The p ortima 38 otthefirst carriage intermediate the ends 35 and -31 is preferably elevated, and is conveniently constructed; from a piece' ffiatstock sm'ewed to; the blocks 36 and 31 at 39 and; e

A furthercarriage M is mounted on thetracks 3.0 and 34 f or, movement transverse with regard to, and underneath, the .firstcarriage 35.- For this purpose-thelcarriage M has abore '42 therethrongh, through which the bar 3i extends, and the other end of the carriage is slotted, .or otherwise machined, to engage and slide-along the bar 30,215. shownat43.

A a first crank is rotatably' mounted on: the .first carriage 35. Thiscrankconsists-of a shaft portion 44 rotatable in the intermedite portion fl .-of the first carriage. Amanually operable crank operator, orcrank arm 45 extends through abore inthe; crank; shaft 44. Its. length may: conveniently. be adjusted by ioneitudinalmovement-0f the arm relatively to the shaft portion 44 and subsequent tightening of a set screw 46.

The second carriage 4l likewise is provided with a crank whose shaft portion 41 extends through, and is rotatable on, the body of the carriage 4|. The top portion of the crank shaft 41 in the illustrated embodiment is milled out at 48 to receive a bar 49 which forms the crank arm for the second crank. The bar or arm may be provided with a graduated scale 50 for adjustment relatively to a mark on the shaft portion 41. A

set screw 52 serves to arrest the bar in adjusted position.

'One end of the bar or arm 49 has non-rotative engagement with the shaft 44 of the first crank. As shown particularly in Fig.2, this is conveniently accomplished by milling a flat surface 53 on the end of the crank shaft 44. A set screw 54 bears against the fiat surface and prevents the crank shaft 44 from turning with regard to the bar 49.

From the foregoing it is apparent that the distance between the axis of the first crank shaft 44 and the axis of the second crank shaft 41' may be adjusted by sliding the bar 49 longitudinally within the milled out portion 48 of the crank shaft 41. The scale 50 aids in this adjustment, which is the adjustment of the instrument for an ellipse having a long axis of predetermined length. The bar 49 is set in adjusted position by tightening the set screw 52. The milled out portion 48 of the crank 4'! is so dimensioned that the crank shaft 44 may be moved into coaxial position with the crank shaft 41. If this is done, the instrument draws a circle.

The bottom end of the crank shaft 41 is likewise milled out at 55 to accommodate an arm 56. The arm 56 also may be provided with a graduated scale 5'! readable on a mark 58 on the crank shaft 41. The scale 51 indicates the distance of the scriber 59 from the axis of the shaft 41 and permits pre-setting of the instrument for an ellipse having a short axis of predetermined length. After adjustment the bar 56 is arrested by a set screw 60.

The scriber 59 may be a pencil, pen, stylus, engraving tool, or any other means for outlining the desired curve, and is preferably mounted in such a way as to be movable towards, and away from, the drafting surface on which the instrument rests. Provision is made in this connection to urge the scribing means towards the drafting surface. The bias force may be exerted by gravity, but in the illustrated embodiment is derived from a fiat spring 6| secured to the arm 56 at 62. The end of the flat spring carries a socket 63 for the scriber. In the illustrated embodiment the scriber is shown as having the form of a pencil point 64 passing through a bushing 65. It is arrested in adjusted position by a set screw It is apparent that the spring pressure with which the point 64 bears against the drafting surface can be adjusted simply by projecting the brought into co-axial position with the crank shaft 47.

' a straight line.

In this position the instrument draws The use of the apparatus is evident from the foregoing description. The instrument is set for the figure to be drawn, for example an ellipse, by adjusting the length of the arm 49 of the second 4 crank 41 and adjusting the length of the scriber arm 56. The scales 50 and 51 aid in this adjustment. Rotation of the operating crank or handle 45 then causes the desired outline to be drawn on the surface on which the instrument rests.

It is apparent that the scriber arm sweeps the area between the four legs of the instrument. The distance of this arm from the drafting surface is very short. This feature contributes to accuracy of the drawn outline. Great accuracy of the instrument is further due to the provision of relatively widely spaced parallel tracks for both the first and the second carriage. This arrangement prevents binding of the movable parts, reduces friction and results in great accuracy without requiring unduly close tolerances in the machining of the parts. For example, the play between the first carriage and its tracks may be adjusted by rotating the second bars 30 and 3|, it being understood that each bar has a righthanded thread at one end and a left-handed thread at the other. Turning of the bars thus results in a change in the spacing of the tracks 28 and 25 straddled by the first carriage 35.

The second carriage 4! had a long bore'42 within which the bar 3! is guided. The axis of the second crank 4'! lies close to the bore 42, whereby smooth operation of the second carriage is insured.

Ihe entire instrument is compact and relatively small, yet it permits relatively large figures to be drawn since the scriber may sweep the entire area between the four legs l4, l5, 1 and i1.

The instrument is conveniently adjustable for the drawing of predominantly large or predominantly small ellipses. In the position shown in Fig. 1, the scriber 59 is on the same side with regard to the shaft 41 as the shaft 44. Thus adjusted, the instrument draws ellipses, the long axis of which is parallel to the tracks 28 and 29.

If very large ellipses are to be drawn, the arm 56 is removed from its slot and reinserted from the opposite side, so that the scriber 59 is on the opposite side of the shaft 47 with regard to the shaft 44. In this position, the instrument draws ellipses, the long axis of which are parallel to the track 30 and 3|. The scriber may sweep the entire space between the legs, corresponding to the short axis, and move considerable distances beyond the bars l2 and 13, thereby permitting unusually large ellipses to be drawn.

What is claimed is:

1. An ellipsograph comprising, in combination, a pair of parallel first bars, substantially of C-shape in elevation, the ends of the C constituting legs, the bight of the 6 being substantially straight and constituting first tracks; a pair of parallel second bars secured to, and extending between, said first bars at right angles to said first tracks, said second bars spacing said first bars apart and constituting second tracks; a substantially I-shaped first carriage, the ends of the I straddling, and riding on, said first bars, the portion of the I intermediate the said ends being elevated with respect to the points of engagement of the ends with said first bars; a first crank shaft rotatably mounted in said elevated portion of said first carriage; a manually operable first crank operator secured to said first crank shaft above said elevated portion for turning said first crank shaft; '2, second carriage slidably mounted on said second bars for movement at right angles with regard to, and underneath the elevated portion of, said first carriagejh second crank shaft mounted in said second carriage; a crank arm extending through said second crank shaft for longitudinal adjustment with regard to the said second crank, the end of the crank arm being non-rotatively secured to said first crank shaft underneath said elevated portion, the longitudinal adjustment of said crank arm permitting variation of the distance between said crank shafts; a scriber arm extending through said second crank shaft underneath said second carriage for longitudinal adjustment with regard to said second crank shaft, said scriber arm extending substantially at right angles to said second crank shaft and sweeping an area below said second bars and between said legs; and scribing means mounted on said scriber arm.

2. An ellipsograph comprising, in combination, a pair of parallel first bars, substantially of C-shape in elevation, the ends of the C constituting legs, the bight of the being substantially straight and constituting first tracks; a pair of parallel second bars secured to, and extending between, said first bars at right angles to said first tracks, said second bars spacing said first bars apart and constituting second tracks; a substantially I-shaped first carriage, the ends of the I straddling, and riding on, said first bars, the portion of the I intermediate the said ends being elevated with respect to the points of engagement of the ends with said first bars; a first crank shaft rotatably mounted in said elevated portion of said first carriage; a manually operable first crank operator secured to said first crank shaft above said elevated portion for turning said first crank shaft; a second carriage slidably mounted on said second bars for movement between said second bars and at right angles with regard to, and underneath the elevated portion of, said first carriage; a second crank shaft mounted in said second carriage at a point between said second bars and immediately adjacent one of said second bars; a crank arm extending through said second crank shaft for longitudinal adjustment with regard to the said second crank, the end of the crank arm being non-rotatively secured to said first crank shaft underneath said elevated portion, the longitudinal adjustment of said crank arm permitting variation of the distance between said *crank shafts; a scriber arm extending through said second crank shaft underneath said second carriage for longitudinal adjustment with regard to said second crank shaft, said scriber arm extending substantially at right angles to said second crank shaft and sweeping an area below said second bars and between said legs; a scribing arm extension; at fiat spring securing said extension to said scribing arm with freedom for the extension to move towards, and away from, the plane of said second bars; and scribing means mounted on said extension.

ARTHUR E. RANDLES.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 296,100 Abbott Apr. 1, 1884 1,017,287 Gran et a1. Feb. 13, 1912 FOREIGN PATENTS Number Country Date 1,092 Great Britain 1910 70,452 Switzerland Sept. 16, 1915

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