[1]Patented July 28, 1936 21049 303 .UNITED STATES PATENT OFFICE 2,049,303 RULER Charles R. Little, Cleveland Heights, Ohio AppUcation April 1, 1931, Serial No. 526,913 8 Claims. (Cl. 33-107) This invention relates to rulers and has especial reference to rulers employed with protractors such as form a part of drafting machines. More particularly the invention relates to improvements in the chucking facilities heretofore applied to rulers to enable them to be chucked in the chuck arms of prbtractois. . The principal object of the present invention is to provide improved chucking 6r holding of 10@ parts, and which permit chucking below the top surface of the ruler so as to make the rulers more convenient for use and cause them to have an improved appearance. When wooden or other rulers are chucked in a protractor such as forms a part of a drafting machine, it has been customary to chuck the ruler at its top surface, this being usually done by securing to the top of the ruler a chuck plate which extends for some distance from the end 20 @tlong the top of the ruler. In order that the ruler may be reversed, these chuck plates are I provided at both ends of the ruler, and these, of c6urse, add to the weight of the ruler, and, a8'the chuck plates are located on top of it, they 2.5 ifttei fere somewhat with the use 6f the ruler, particularly when the rulers are in the form of scales, g,nd they detract from the appearance of the article. AR these disadvantages are overcome and @the 30 advantages or objects stated above are attained Veryeffectively by the present invention, which niasr be here briefly summarized as consisting in dertain novel details and combinations which will be described in thespecification and set forth 35 in the appended claims. In the accompanying sheets of drawings which Show the preferred embodiment of the invention, I Flgure I is a top plan view of the ruler with 40 portions brokerl away, this ruler being in the form of a scal6; Mg. 2 is a bottom View of the same; Mg. 3 is a cross-sectional view of the same on ah enlarged scale; 45 'Flg. 4 is a similar view of the scale,@the section being taken through one of the chucks of the stale and through the chuck a;rm,, and n'g. 5 is it plan vi6w of a protractor *ith two' rulers, portions only of which are'shown, held ,50- on the chuck arms at right anglbs to ear-h other. Ri@f erring to the drawings, the ruler shown therein include8 a nietql gtiffening core I 0 and gt suitabl6 nonmetallic covering I 1, such as celIttloid or pyralin, which enclosds the core and is 55 of cours'e tightly fitted thereon. The core IQ ii p referably formed by extruding and drawing p rocesses from a swtable hght but stiff metal, s uch as duralumin or magnesium ajloys. In the p referred way of producing the core, a strip havin g the approximate cross-sectional shape of the 5 c ore and of suitable length is extruded and is th en passed through drawing dies in which the d esired cross-section is obtained. It is then @laced in a stretching machine to straighten it a s much as possible, and after cores of proper 1 0/ le ngths for use in the rulers have been cut from th e strip, the cores are subjected to a further st rai.-htening operation by subjecting them to s evere pressure in a press between dies which a re 7shaped in conformity with the shape of the 1 5 c ore. The covering is preferably applied by heat and p ressure in a mold, as described in my United S tates Patent No. 1,728,420, the covering of c ourse, enclosing the core, including the top and 2 0 b gttom surfaces and the ends, although certain li ortions of the covering on the center line of th e top are later removed to acconunodate the h eads of screws which hold the chucks to the u nder channelled surface of the ruler. The rulers 2 5 m ay be in the forin of scales or straight edges, b ut If in the form bf scales, the top will usually b e beveled along both sides and the beveled surfa ces will be provided with the usiial graduations a nd characters. If the ruler is in the form of 3 0 a straight edge ' the bevels will usually be omitted fr om the top .zurface of the ruler. According to the provisions of the present inv ention the ruler is provided on its lowdr side and extending centrally from end to end with 35 a channel which I prefer to be somewhat greater th an one-half the width of the ruler and that it s cross-section be approximately one-third of th e cross-sectional area of the ruler. The top w all of the chonnel Is, of course, parallel to the 4 0 to p of the ruler and its side walls are slightly ta pered. This channel has numerous functions, and has ut ility both in the production of the core and th e ruler as a whole and in subsequent use, parti cularly when chucked in protractors such as fo rm a part of the drafting machines. Perhaps it s greatest utility lies in the fact that it admits of a greatly improved method of and irieans for c hucking the ruler, but this will be referr6d to 5 0 p resently. Among the other advailtages utilized in the manufacture of the ruler and in its use in dependently of protract6rs and the chuck atms th ereof might be mentiolied the following. The c hannelled section of the core increases greatly 5 5
[2]the stiffness of the core and thus enables me to use a stiffer metal without increasing the weight, or, as otherwise stated, as compared with a core such as shown. in my prior @,patent, it will have considerably less weight if metal of the same kind isempl6yed. The channel is useful in pr6ducing the core itself for it enables me to produce cores free of twists and bends which was not always the case 10 with the unchannelled cores. I-Teretofore I experienced considerable diffteulty in obtaining cores which were truly straight. In producing a quantity of cores, a portion of them wowd be straight when produ-ced by the methods de15 scribed above, but others would nOt be soi but extruding the strip, passing it through a drawing die, stretching@ the strip, and then after the strip is cut into core lengths subjecting their., to 20 pressure between' dies iii a press, the cores are uniforii)ay: straight to @ an e-.@tr6mely high @'d--gree of @ accuiacy. This i6sult is- @obtOinOd becau8e by utilizihg straighteiiing dies, the lower one of which is provided I v@ith @a part which conforms 25 to @the shape of the@ channel and of course ext6rids f 6r@ its full len@th, the @ upper die - of - the piess, when'it strikes th6 core which is easily correctly placed and held on the lower die with 'd part fflli the'ehannel, iemoves the last sal ng 30 vestige of any twisting or bending distortion, with the resultithat the'cores afe Prodiieed uni@ formly straight. Finallk, it peifotms 6, vei-y useful fiinction iii thdt pa-rt of -the @ process @ of f o@ming the rulers 35 wherein the n on-metallic covering is molded by heat and pressure around the core. In this connection it' might be stated @that previous to the conce - ption of the channelled-@6ore difficulty was bncountered by me in @ keeping@ thi@ c6re ce-ntral 40'. iind in keei@ing it frdm bending @ when subjected t(i 'the enormous pressure necessary in molding the @oii6-piece unitary covering around the core. Iri producing a quantity of rulers the cor@s df sonie 6fthem would be pr6peTly positioned but 45 not @ so :of bthers, I found that in some instan-ces the - c6res had @ a; tendency - to fi6at, so to speak,- in .the celluloid -so that they would @ nbt be centrally. pbsition@d thet@in. To ovbrcorhe this, I @attemlited to hold the cbre in position by spaced 50 pins engaged in openings of the core, but this ex.; pedi6nt would not @uffice in some ir-istandes for the pressure of th6 celluloid on the core seemed to bbnd it. @ These dififteulties are. entirely: overcome by the bhanhellod co-re @ for I find thot in 65 mblding the @non-metallic plastic @ material around the core with a rib on the lowet mold member extending for the full leligth itto the,channell the shifting of the'core:in@the mold and the benditig ',of the core -.are @eliminatod so, that iii 66 the prodiletion of a-queintity bf these rulers they are gubstantially uniform in the deSiTed centralized relationship of the core in the celluloid or dther covering material. @A greater advaiitage of the channelled rulers 65 lies in the, fact that by reason of the channel I -am enabled t6 chuck the- ruler -on the chuck holding @6rm 6f a protractor with the chucking below the top -surface of the ruler, in fact on the @under side @ the'reof. - For the accomplish70. ment of this I provide on the under side of the iulet and against the' upper wall of the cbannel a'@plur.ality of independent chucks which are adapt6d to engage and interlock v@it-h the chuck arm which is -extended into the channel and con-@ 7 f6rms substantially.@ to the -cross-sectional shap5 thereof, the chucks being so formed that they will engage in. suitably formed slots in the chuck arms. The form and location and the manner of securiyig the chucks @in the channel are well illustrated in Figs. 2, 3, 4, and 5, wherein the 5 chucks are designated by the reference character 13. The number of chucks which are provided for each end of the rwer 'will generaily depend upon the length of the latte-r. I prefer to employ two or more for each end of the ruler. 10 I find that for a twelve' inch ruler tto chucks are ample, but f6r longer rulers, such as - eig4teen @ill-ch@ I prefer to employ thtee chucks at e@ch end, these chucks bei,ng equally spaced. Each 6huck is formed - from a piece @ of metal - @lightly 15 which ektendilongitudinally of t,he iuler and are slightly tapered, being slightly convergent. toward the adjacent end of the ruler, i. e., toward the protr@ctbr in 'which they are to be chucked. 20 the- flat Likewise, the walls - fo'rmiiig - @ side@ - dre slightly tapered toward- the top (if -.the chaniiel@, as shown at l@3b in F19. -3. Each chuck is- held in place against the up@er. wall of@ the channel a.,nd centtally of the 12@tter by a@ . sixiall screw 14 25 th-fough an opening in the ruler, which opehi.ng is somewhat larger @ tha;n thb shank of the sci!ew so: t'hat -the scr.ew, and therefore, tho @ chuck, @ may be adj- sted in aiiy u -ditection The, head @ I 4a of the screw, which-is preferabiy flat @ and circular 30 and of a thickness only very slightly, if any, greater than the thickness of the @ covering @ on, the core, bears against the core, as clearly shown, in F-.-g. 4, the covering being cut away -so @ as -to provide clearance for tho head. Obviously,:when 35 the sc-rew is tightened, the chuck, is@ &awn up tightly against the upper wall of .the charinei, and prior to tightening it, the chuck@can be'@given the desired.positioning so that,it will properly fit the slot in :the chuck -arm. This@ method Of 40 chucking is especially wel.1 adapted- f,o,r quantity production. In Fig.@ 5 I have shown how the chucking is ac@ complished. I have here shown rather @ conventionally a@ pr6tractor which forms the subi.e c t 4 5 @ matter n. a-pi)lication - Serial No. . of a companio 526,912 :filed of even@date@herewith.@ It wiii@ @e@ sufficilent to state that this protractor@includes a protractor plat6 16 which is pivoted tb the center of i and is rotatable with respect to a notche @ a @ 5 0 holding plat-- 17. The prbtractlor i,ncludes also a chuck arm plate I 8 having. two chuck arms 19 and 2 0 to which the rulers are adapted -to be chucked, these arms being. as usual at- right angles to each other- A protractor of this@kind 55is generally secured to the parallel motion mecharli@sm bf a drafting machine, the notched plate17 having,extensions 17a by which this may-be bro-ught about. Additionally,-,the-ptotractor has a centra,lly located handle 2.1 @ which is grasped,by co the operator when the protractor plate-and rulers are tG be -turned and there is supported: in this instance by the :chuck arm@ plate 18 'a ratchet pawl 2 la the nose of which is adapt.ed to. snap, into the -notches of the notched, plate@ 17 @to 65@ position the protractor when -it is turned @and, tohold it inthe commonly used: angles, the pawl being released from the notched plate by, a suitable thumb-piece 22. b.6fore stated; the chuck arms 19 and. 20.70 are at right angles to -each@ other and one is longer@ than the other@so as to accommodate rulers of diffe-rent lengtbs. @ These chuck@ arms in cross-section conforin to the cross-section@ Gf the a p t e d t o e x t e n d i n t o @ t h e 7 5 cliannel and the are ad ' Y when I produce these channelled c6res by -first, elongated in form with flat sides, 13a (Fig. 2) 2,049,303
[3]channels:of;th6@'rul@rs7@wheii th6 la@tter@@ire chucked thereto. ;.The thickness of. the chuck arms @ ig about @ the same or slightly - less than the depth bf .the channels, @as inclicated@ in Fig. 4. Each of these chuck arins has a plurality of slots 23 which. extend transvergely through the chuck arms centrally'thereof, @which slots:are adapted to receive the chucks 13 of the corresponding rwer. The number, of th@se slots will'depend 10 upon the number of chucks with. which the ruler is provided. That i's to , saY, fdr a ruler@ liaving two chiteks at each end, the e-h7ick arm will have tw,o bf these;81ots"ia;s'shown..in the I shorter chuck 'a,rin:i 19. @ If t-he rweir h-is thre,e or more chucks 15 at each end, the chuck arm will@ hav I e a correspondingnuinber Of@equally spaced slots, as provided in the chuck arm 20 which is shown as having three slots adapted to receive three chucks. These slots have tapered sides, the nar20 rower ends of the slots being prefer-ably toward the protractor and the side walls of the slots are undercut, as indicated in Fig. 4. The relatively large ends of the slots are wide enough so that the chucks will slip into the slots, and in chucking 25 the ruler it is placed over the chuck arm with the channel receiving the chuck arm and with the chucks in the larger end of the slots, -and then the ruler is slid in this instance toward the protractor, whereupon the chucks will engage 30 tightly the side walls of the slots and the chuck arm will be pulled up against the bottom of the channel, as in Fig. 4. To release the ruler, it is merely necessary to slide it outwardly and then lift the ruler off the chuck arm. 35 Thus, with the chucking me-ans herein shown, the top of the ruler is clear and not obstructed as heretofore by a chuck plate and by a chuck arm extending for a distance over the ruler. This adds to the convenience in using the draw40 ing instrument and improves its appearance, the ruler for its full length being unobstructed by parts which heretofore have extended over a portion of its length. The use of two independent chucks instead of 45 one has several advantages. Two small chucks, such as herein illustrated@ spaced apart as shown have less weight than the single long chuck heretofore necessary. Additionally, the two chucks provide four bearing surfaces on the chuck arm 5( instead of three as heretofore. In consequence, there is a better holding action which reduces materially the flexibility of the ruler and therefore adds to the accuracy of the instrumenb as a whole. Either or both of the two chucks (or 55 three if three are employed) can be independently adjusted so that perfect alignment can be obtained and to bring about equal bearing actioii of both sides of the chuck on the chuck arm, it being understood that the cliucks have the neces60 sary lengthwise and crosswise adjustment tG -at_ tain these ends@ Finally, it might be stated that a plurality of chucks formed and spaced apart as Ulustrated and described do not have the disadvantage of a single relatively long chuck in 65 that the latter at times would bend and had a certain amount of springiness' all of which had the tendency to effect the alignment of the ruler and to Increase its lateral flexibility to the detrima.nt of accuracy. To From the above it will be seen that the crosssectional shape of the composite ruler has advantages independent of those whi6h flow from the new chucking features. It will be seen also from the above that the use of two or more 75 separate chucks at each end of the @uler in3 stead of i,single lolig chuck has advantageg @regardless of whether the chucking is done on the under side of the ruler or on the top@ The - arrangement of the separa@le chucks in the channel and the method of chucking herein@described Are -Z preferred, but I regard it within the .-cope 6f @my invention to use chucks similar to those described but mounted ori the top surface@ of the ruler with the heads of the screws in the channel, in which event the chuck arm wjil extend lit@ over the ruler and engage the chucks as before. It will be seen from the above that my improved channelled ruler either in the forni of a scal,6 or a straight edg.@ has numerous advantages in per" mitting a-li increase in the stiffiiess and a redue- 15' tion in weight and facilitates the manufacture of composite ;Uiers having a metal core and a covering of celiuloid or the like, and, together with the chucks preferably secured in the channel, perniit a greatly improved method of chuck- 20 ing with numerous attendant advantages over the method or methods heretofore employed. While chucking in the channel of the lower side of the ruler, as herein explained, is highly desirable, nevertheless I do not desire to be con- 25 fined to that method of chucking. For example, the channelled ruler and the use of two or more separately and independently adjustable chucks at each end of the ruler are important whether bottom chucking or top chucking is em- 30 ployed. Of course, if top chucking is utilized, the chucks will be secured on the top side of the ruler with the heads of the screws engaging the top wall of the channel and the chuck arms would extend over the ruler and engage the chucks as 35 before, but, of course, with that arrangement onl y part of the herein-mentioned advantages wo uld be attained as compared with the prefer red construction, and therefore the preferred me thod of chucking herein described and illus- 40 trat ed. While I have shown the preferred construction, I do not desire to be confined to the precise detail s as changes may be made without departing from the spirit and scope of the invention, 45 an d I therefore aim In rny claims to cover all suc h modifications. Having thus described my invention, I
