US2540848A - Curve describing instrument - Google Patents

Description

Feb. 6, 1951 F. L. A. TURNER CURVE DESCRIBING INSTRUMENT Filed May 19, 1944 Fig.

Patented Feb. 6, 1951 UNITED STATES. PATENT OFFICE CURVE DESCRIBING INSTRUMENT FrancisLesley Anthony Turner, Montreal, Quebee, Canada, assignor, by mesne assignments, to Patrick Harrison & Company Limited. Noranda, Quebec, Canada, a body politic and corpox-ate ApplicationiMaylll, 1944, Serial No. 536,385

2 Claims. 1

ing a description containing an explanation in.

detail of acceptable forms of the invention.

The objects of the invention are to devise an instrument which will facilitate all. types of engineering drafting, due to the factthat it may be manipulated to accurately draw predetermined size of ellipses, parabolas, hyperbolas, cycloids,

right and left spirals, 'ships curves, log. curves,

and other type of curvatures utilizing pen, penoil or other marker; to speed up the work of draftsmen and others and reduce errors to the minimum, through eliminating manual calculations by the engineer in the compass portion of his work in drafting; to construct. an instrument that will be quickly and easily understood by the draftsman, engineer, student and others and, simple to operate and compactiu form; and gene erally to provide a drawing instrument that will be accurate in its calculation, and efiicient. for its many uses.

In the drawings:

Figure 1 is a side elevation of the drawing in.- strument.

Figure 2 is a fragmentary sectional .viewof. the drawing instrument.

Figure 3 is a fragmentary plan view of the instrument.

Figure 4 is an enlarged detail of one of the many cams applicable to the instrument.

Figure 5 is a plan View of the cam as illustrated in Figure 4.

Like numerals of reference indicate corresponding parts in the various figures.

Referring to the drawings, the drawing lZlstrument as illustrated and hereinafter described is in the form of a two legged type of instrument, but it will of course be understood that the main features of this invention may be introduced in other types of drawing instruments without in any way departing from the essential features of this invention, in devising an instrument which may be adjusted accurately to the predetermined degrees and automatically draw the predetermined configuration, sim ly by the operator manually turning or otherwise operatingthe instrument.

The instrument consists of the centering. leg as indicated by the. numeral ldhaving at its lower end the centering member if, secured thereto by the fastening member I2 and provided with a plurality of prongs l3; lhe centering log it! has at its upper end the threaded neck M provided with the shoulders l5 which support the in. drawing instruments as described, in the present.

. strument. The rotatable bracket finger grip shaft i t, the latter having a threaded opening engaging neck portion it of the centering leg. This finger grip shaft it, which be termed an axle, has the shoulders ii o which the rotatable bracket 58 is mounted, the rotatable bracket being held in position by the lock nuts 59, which in turn are threaded on part of reduced end portion 25] of the finger grip shaft l5. The rotatable bracket H has a finger grip 2. 2 mounted on its upper end and this finger grip i turn has an orifice in its underside in which is rotatably mounted the upper portion of the finger grip shaft Hi. This finger grip 22 is knurled and serves as a means for rotating the drawing inlii has the protruding lugs 23 which form a journal for the marker leg 2d; the latter may be adjusted'with respect to diameter or size by means of the thumb screw 25 of which the inner end contacts curved face of pawl 55, the straight face of the latter contacting shaft El which is secured to sliding member id. The slot 53 in the upper end ofthe marker leg. 2 1 allows movement of the pawl 52. The horizontal fingers of guide member 34 slide in groove 58 of the finger grip shaft it. The lower portion of guide member it, that portion parallel to center line of instrument, forms tinger supports for the lever slide 43, as well as curved supports 53. for marker leg 24, The tapered adjustment screw ll fits in a tapered groove in the lever slide 43, the latter also having in its underside a longitudinal groove 55 which guides wheel at. Rods 5 5 support outer end and vertical fingers of guide member it. This guide member and marker leg 2t and their component members are provided with tension springs 45 to hold said members yieldingly together; springs 45 are secured to horizontal fingersof M by pins as well as to 24 in a like manner, they are also attached to and suspended by equalizer rods it. The marker guide 2? is slidingly enclosed by cylindrical casing 32 having an aperture through which pin 33 extends for engagement with aperture 34 of marker guide. The marker guide 2? is provided with a cam face 56 suitably shaped to cause the marker leg to make the requisite configuration, by forcing the casing 32 to rise or fall under tension of the spiral spring 49, thereby forcing the marker leg i i outwards or inwards respectively by the action of the wheel 42 on the leverslide it. An adjustment screw 35 extends through an orifice in casing 32 and is provided with pointer or indicator 3% for measuring oii specific degrees from the graduated circular face 3'! which secured to casing 32. The adjustment screw 35 is held in place by a set screw 5%} which fits in a circula groove in 35, and the inner portion cftfi; is specially threaded to fit specially threaded orifice in yoke member 38 which is in turn ecured by a shaft to the arm 39, the latter being secured by a second shaft in a slot in the top of the casing 32. it indicates a roller or other rounded face attached to the arm which rotates around leg ifland is in contact with cam face 56 of marker guide 2?. In this way the roller 53 may be adjusted and placed where desired on face 5% by the lateral movement of the yoke 38 in accordance with selected degree as indicated by as on 3 1, to make the necessary configuration. The adjustment screw ll? with indicator is set on a graduated disk it to correspond with the setting of the pointer 35, on the face 3?. When adjustment screw i'i is turned clockwise one unit the lever slide it moves inward one unit or degree also one unit turned on 35 causes wheel it to move one unit. These adjustments are for to 530 degree elli ses, etc. When the screw 35 is turned and the pointer 33 points to e, the roller iii will be on contact face it at upper extremity of cam face of marker guide 2'! and thus when 22 is rotated marker Reg 2% will describe a circle, since there will be no change in level in the arm 33 and the casing The diameter is set by thumb screw 25. The helical tension spring encircles centering leg iii and yieldingly holds cylindrical casing 32 and its component members or parts namely lii, against cam face 55 of marker guide 2?. Screws 29, til and 3! must be screwed firmly against leg id, and pin 33 must be removed from orifice when drawing configurations that join such as ellipses thus holding 2'! stationary while allowing 32 to revolve. In Figure 2, 52 indicates a right hand helical groove and 55' a left hand helical groove, 29 and 3c are threaded thumb screws with a reduced rounded end portion to fit the helical grooves in leg it thus when 32 is held firmly to 2'! by pin 33 in 3d, and 722 turned right or left with i? et to desired degree of pitch, marker leg 24 will describe a desired spiral. In other words all members enclosed by casing 32 and also those attached will move upward or downward and wheel i2 moving in groove 55 will force leg l0 inward or outward. Grooves 52 and 53' in leg is can be made in any manner to attain desired configuration. This completes the general construction of this instrument and through manipulating the thumb screws and adjustment screws and changing or replacing the marker guide 2'? or leg it and/or other guide members many curved configurations can be made accurately without the need of any instruments. Such configurations will be on an accurately pre-arranged scale.

In order to more readily understand the instru ment various applications of the device are described in making different configurations, but needless to say other applications may be made without departing from the essential features or this invention.

If an ordinary circle is wanted, place centering member ii at center of desired work, set 2d to desired radius by 25, then if pin is out and 29 tight, set 36 at zero on 3'5: use as ordinary compass. If 33 is in orifice as, set 29, 353 or 3i in horizontal grooves on leg it, then use as an ordinary compass. Circles can be described with any combination of set ups.

When it is required to describe an ellipse, the thumb screws 29 and 3b are tightened to secure the marker guide 2'? to .leg it, the major or minor axis is then set by adjusting the screw 25. Turn '35 so that 36 indicates proper degree, then set the same on 48 byturning 41. 4'! causes 43 to move to desired degree; the instrument is then used as an ordinary compass. The instrument is set in like manner for describing parabolas, cycloids etc., but remembering that 27 must be changed to suit the desired configuration.

This instrument will also describe, with special attachments, epicycloids, hypocycloids, an lIlVO! lute of a circle, and any other special or irregular figure made up of curves.

What I claim is: a

1. In drawing instruments, a centering member having helical grooves of predetermined pitch, a cam mechanism encircling said centering member, a casing enclosing the upper portion of said cam mechanism, adjustment means adapted to connect said cam mechanism to the helical grooves of said centering member, a detachable member adapted to secure said casing to said cam mechanism, a rotatable bracket mounted on said centering member, a finger grip integrally attached to said rotatable bracket, a marking member pivoted to said rotatable bracket, a guiding arm and roller mechanism secured to said casing and engaging the cam face of said cam mechanism to move said casing up and down in accordance with the shape of said cam face, adjustable means between the casing and said marking member for producing pivotal motion of said marking member in accordance with the up and down motion of said casing, and means for adjusting the said guiding arm and roller mechanism according to predetermined data for drawing a predetermined curve.

2. In drawing instruments, a centering member having helical grooves of predetermined pitch, a cam assembly encircling said centering member, a casing enclosing the upper portion of said cam assembly, adjustment means adapted to connect said cam assembly to the helical grooves of said centering member, a detachable member adapted to secure said casing to said cam assembly, a rotatable bracket mounted on the upper extremity of said centering member, a finger grip integrally attached to said rotatable bracket, a marking member pivoted to said rotatable bracket, a guiding arm and roller pivotally attached in the top portion of said casing and contacting the cam face of said cam assembly and adapted to motivate the casing in variation in level relative to the said cam assembly, means for adjusting the position of the said guiding arm and roller relative to the centering member according to predetermined data for drawing a predetermined curve, and adjustable means between the said casing and the said marking member for producing pivotal movement or said marking member in accordance with the up and down motion of said casing.

FRANCIS LESLEY ANTHONY TURNER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS

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