US 3037293 A
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Description (OCR text may contain errors)
June 5, 1962 F. L. YOST 3, 37
SPIRAL CURVE DRAFTING INSTRUMENT Filed June 28, 1960 INVENTOR.
A'rraelver United States Patent 3,037,293 SPIRAL CURVE DRAFTING INSTRUMENT Francis L. Yost, 5910 Wellesiey Ave., Pittsburgh, Pa. Filed June 28, 1960, Ser. No. 39,326 2 Claims. (Cl. 33-174) This invention relates to a spiral curve drafting instrument and has for an object to provide an improved drawing or templet aid with a precisely graduated curve, to be made of any suitable transparent sheet material, such as a transparent plastic, sometimes commercially known as Plexiglas and also by other commercial names, or other similar material, preferably although not necessarily about ,1 thick and 11 /2" in diameter.
A further object of this invention is to provide a drawing aid or device for artists, engineers, draftsmen and architects, and others, and is generally intended for use when one is constructing a drawing that requires a curve on the drawing or plan, or on another flat surface.
A further object of this invention is to provide a drafting instrument that eliminates the need for the usual col lection of French curves, eliminates the need for looking over a collection of various drafting instruments to locate a desired curve, that provides in a single instrument, a number of precisely graduated curves, and also provides an identification for each portion of the curve which enables the user to readily refer thereto and to readily locate the identical curve again when needed,
A further object of this invention is to provide a drafting instrument which includes a plurality of spiral slotted curves therein, distinctly identified for ready reference, all about a central reference point, with each curve a spiral continuation of the other curve thereon, and with an identification means generally locating the curves within separate quadrants, and further to provide a central point about which the curves are generated to enable the user to establish perpendiculars to any arc, with boundary lines between each quadrant extending diametrically from such central point.
With the above and related objects in view, this invention consists in the details of construction and combination of parts, as will be more fully understood from the following description, when read in conjunction with the accompanying drawing in which:
FIG. 1 is an elevational view of the spiral curve drafting instrument of this invention.
FIG. 2 is a transverse sectional view on line 22 of FIG. 1.
FIG. 3 shows the generation of the spiral curve.
Referring in greater detail to the drawing wherein similar reference characters refer to similar parts, there is shown at 10 the spiral curve drafting instrument of this invention comprising a body made of a thin sheet of transparent plastic material such as Plastiglas or other similar materials of which drafting instruments of this general nature are usually made, being preferably about 5 thick by about 11 /2" in diameter. This body is divided by boundary lines 12, 14, 16 and 18 into four quadrants, the boundary lines stopping just short of a center point or dot 20. This center point or dot 20 may be merely indicated on the surface of the body 10, or, if desired, may be in the form of a small opening through the body 10, just large enough to insert a pen or pencil point therethrough,
Each of the quadrants are designated A, B, C and D, and in this description, such designations are also used as reference characters. On this body 10, a spiral curve,
Patented June 5, 1962 ICC of a desired size, is generated by winding 21 tether such as a fine strand of piano wire 28 about a steel shaft 30 A" in diameter at E, coil-fashion counterclockwise, placing the shaft 30 at the center 20, attaching a marking device 32 on the end of the Wire, the marking device 32 being maintained parallel to the shaft. With the wire 28 held taut, the marking device 32 is moved in a constantly increasing radius R creating a steadily increasing breadth of arc. The same spiral used in generating the slot curves is continued to generate a spiral periphery curve A1, be ginning at 22 at quadrant A continuing at B1, C1 and through D1 ending at 24 in quadrant D, and the two ends 22 and 24 of the spiral periphery curve are joined by a smooth reverse S curve 26. Of course, the curvature of the arc may be changed by using a different size shaft.
Then, when the desired spiral has been established, the body will be slotted as shown, keeping all but the innermost slot within a particular quadrant as defined by the boundary lines 12, 14, 16 and 18, the innermost slot extending through two adjacent quadrants. The peripheral or edge curve in each quadrant is designated by the numeral 1, the next curve by 2, the third by 3, the fourth by 4 and the fifth by 5.
By combining the quadrant designation with the curve designation, each curve portion has its individual designation, such as Al, the outer curved edge in quadrant A, or such as C3, the third curved edge in quadrant C, etc. Thus every curve portion is individually identified, and when a curve is penciled on a drawing or plan, the curve portion designation may be temporarily penciled adjacent thereto, so that when it is inked later on, the same curve may be used therefor.
Although this invention has been described in considerable detail, such description is intended as being illustrative rather than limiting, since the invention may be variously embodied, and the scope of the invention is to be determined as claimed.
Having thus set forth and disclosed the nature of this invention, What is claimed is:
1. A drafting aid template comprising a body of transparent stock having completely flat parallel upper and lower surfaces, said body having a periphery provided by a spiral curve extending almost completely about its peripheral edge and joined at its adjacent ends by a re verse S curve, said spiral curve having a multiplicity of convolutions continuing through slightly spaced apart slots in said body to adjacent a center point about which the spiral curve is generated, each convolution of said spiral, beyond the innermost one, being divided into quadrants by spirally spaced apart slots by radially aligned integral body portions, and quadrant boundary lines extending across said integral body portions from adjacent,
said central point toward the peripheral edge of said body.
2. The drafting aid template of claim 1, and alphabet indicia identifying each quadrant, and numerical indicia correspondingly identifying each curve portion in each quadrant.
References Cited in the file of this patent UNITED STATES PATENTS 486,699 Davis Nov. 22, 1892 2,478,071 Agrillo Aug. Q, 1949 2,500,873 Sager Mar. 14, 1950 2,607,118 Debs Aug. 19, 1952 2,933,818 Palmer Apr. 26, 1960