US2605550A - Drafting instrument - Google Patents

Description

Aug. 5,.1952 E. F. CAMPBELL DRAFTING' INSTRUMENT Filed Dec. 9, 1949 INVEN'IOR 35 izzfuaro Cam oell Patented Aug. 5, 1 952 TT;

' Application December 9, 1949, Serial 132.1851

4Clain' s; (01.33-104) 1 i=(Granted-under the act of March amended April,30,-1928; 370 O. G. 757) The invention described herein, if Y patented, may be manufactured and used by or for the Government for governmental purposes without the payment to me of any royalty thereon.

This invention relates to drafting instruments and among other objects, aims to provide a device which facilitates the making of. dotted pencil lines of different characteristics and which isdesigned to obviate scraping graphite from pencil points, which would smear Or-SOil drawings, Other objects will be obvious from th following description of the preferred embodiment of the invention shown. in the accompanying drawings forming a part of this specification;

In said drawings:

Fig. 1 is a plan view of the instrument;

Fig. 2 is a fragmentary plan view on a larger scale of one of the removable line-dotting attachments; I g

Fig. 3 is an enlarged section'on line 3-3 of Fig.1; j i,

Fig. 4. is an enlarged section on line 4-4 of Fig. 2; and l Fig. 5' is an enlarged section on line' 5-5 of Fig. 1. I

Referring particularly to the drawings, the preferred embodiment of the invention comprises a transparent fiat plastic body 6 which may be a 30-60 right triangle as shown or may have many other shapes such as that of a 45 right triangle, an isosceles triangle, a protractor, a square or oblong, or even a circle. Its edges may be marked with scales in inches or centimeters and fractions thereof (not shown). This triangle is provided with three slots each parallel to one of its sides but having no communication with the others. The purpose of these slots will be explained presently.

On the underside I, that is, the surface adjacent the drawing paper, the body 6 is provided with pairs of grooves 8, 9, I0, H, l2, l3, each pair extending parallel to one of the sides of the triangle but spaced therefrom, and terminating short of the other two sides. These grooves have depths of about two-thirds or three-fourths of the thickness of the body and make angles of about 60 or 120 with the plane of the underside 1, as shown in Fig. 3, so that the grooves of each pair converge upwardly.

Interlocked with each converging pair of grooves is a resilient channel-shaped insert or strip l4, l5, l6, each strip being preferably of plastic and having converging longitudinal edge flanges l1, l8 adapted to enter th grooves when the strip has been bent or flexed transversely and adapted-when released to lock with the groove walls by reason, of its resilience. Each plastic strip has a thickness of less than 1 mm. and any convenient length as indicated by the dimensions of the slots in body 6. The purpose of strips l4, l5, I6 is to facilitate forming dotted or dot-and-dash lines and to this end each strip has one or more series of perforations] 9, '20 (or 22 or 24) of different sizes and spacing. Perforations J9, 20 are primarilyfor making two different types of dotted lines by running apencil (in-the, manner indicated in Fig. 4) rapidly-over eitherseries of perforations while guided by the: appropriate edge of slot 25. Perforations 22 in strip 15 are circular and are primarily for making fine dotted lines with the pencil moved along slot 26, while perforation 24 in strip l6 facilitate making do t-and-' dash lines in'conjunction with slot 21. Slots 26 and 21 are narrower. than slot 25 and onlyone series of perforations are; associated with these narrow slots. It will be clearthat many other arrangements and dimensions of the perforations and slots may be employed, Obviously each strip 14, I5, I6 is easily removed manually for replace-v ment with a different strip. If desired, after the strips are taken off, the longitudinal edges of slots 25, 26, 21 may be used for drawing straight lines, and as the several slots may be of many difierent widths they may be employed for making parallel lines spaced different known distances apart without the necessity of measuring such distances.

While the illustrative strips are snapped on and off the body 6, if preferred each pair of grooves 8, 9, or H], H, or l2, 13 may extendto one edge only of the triangle and th corresponding strip may be engaged therewith by pushing or sliding it endwise into the groove ends where exposed at a triangle edge. This will be understood without illustration.

As shown in Fig. 4, the edges of the strips which define or bound the perforations Iii-24 are curved downwardly to cause the lead pencil point to ride over the edges without scraping or abrading any substantial amount of graphite from the point, the result being that no graphite dust is deposited on the drawing paper by ordinary use of the instrument. It is of course clear that the paper would be smeared or soiled if such dust were formed.

In the central portion of the triangle or other body 6, several circular series of perforations 30, 3|, 32, 33 are shown all of which surround a hole 34 whichis at the center of the several circles and is adapted to receive the point of a compass. After placing the compass point in hole 34 the draftsman may make dotted circles of a considerable range of diameters by merely running the lead around over the perforations. The thickness of the body 6 is considerably reduced in the area containing perforations 30, 3|, 32, 33, as indicated at 35, Figs. 1 and 5, so that the compass lead mayv enter'every,perforation as it passes around the circle. Arcuate or curved dottedlines: may be made possible by the provision of other perforations extending in curved lines (not; shown). These supplementary perforationsmay. be dispensed with and a single large hole f'ortl'ie draftsmans fingers may be provided; asyis-conventional in triangles. Other, changes, may be, made within the scope of the appended claims:

What I claim is:

l. A drafting instrument facilitating the making of broken lines comprising a bod'y having a fiat under surface provided with apair of parallel grooves extending up into the body, the body also having a: straight slot: extending between saidgrooves; an elongated flexible striplha-vi'ng' flanges along two longitudinal edgeswhich extend upwardly-intothe: grooves, theshapes of the grooves and 'flangesbeing complementary and suchthat the strip" is-removably locked on the body, the strip havinga very-thin area between itsflangesand having-spaced perforations :in'said thin area, so that a: pencil point -may be thrust through-the'slot fromaboveand'may be run along the slot and over the perforations. through: which: the pencil point passes -to mark a; paper sheet placed under thebody with dots; or dashe's spaced' in accordancewith the spacing s che perfora tions 2. Theinv'entionas: defined claim -1; where-- in the b'ody has the shape of a triangle andQther-e are three pairs of grooves; three slots each asso-- ciatedwith one pair-iof grooves-,-- and three strips; each slot and" associated' pair of grooves being parallel -to one-'offthe sides of the triangle, the slots -having-, no commu-nication with each-other, and 1 the grooves of each pairconverging u'p wardly- 3. A ruling device for draftsmen comprising a flat body portion provided with an elongated slot in one face thereof and a relatively narrow elongated groove located on each side of said slot and parallel therewith, an elongated strip of material provided with a series of openings or perforations extending; longitudinally of said strip, flanges on the longitudinal edgesof said strip disposed in said relatively narrow grooves, the shapes of the relatively narrow grooves and the..fianges being complementary and such that thestrip'is 'detachably connected to the flat body portion.

4. A ruling device for draftsmen comprising a fiat'body portion provided with a slot and a pair of parallel grooves in one face thereof and on either side of said slot, an elongated strip of thin resilientmaterial'provided with an elongated series of openings or perforations, and a pair of flanges integral with the strip and extending longitudinally thereof and interlocking with said grooves when: the; strip is flexedtransverselyto releasably secure said' strip." to saidbody portion, the resilience of. the. strip and the interlocking flangesrand Zgro'oves constituting; the sole means for securing. the-strip, and the-strip being removablemanuallywheneverx it is fiexedtransverse'ly: and its" flanges are movedout of'interlocking engagement: with: said grooves.

EDWARDF. CAMPBELL;-

REFERENCES CITED The followingvrefe'rences are. of record 'in' the file of this patent:

UNITED STATES PATENTS I I Date Number a Name- 1,662,832 Clark Mail. 20, 1928 2,303,676- Bixby D60. 1, 1942 FOREIGN PATENTS Number Country Date.

265,691 Great-Britain Feb. 11,1927

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