US2049303A - Ruler - Google Patents

Description

C. H. LITTLE RULER Filed April l, 1951 2 Sheets-Sheet l 772 06.7?*602L da@ Km Kaw@ rw .N .NWN

C. H. LITTLE RULER Filed April l, 1931 2 Sheets-Sheet 2 Patented July 28, 1936 Stags UNHTE PATENT OFFICE 8 Claims.

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 im- Y provements in the chucking facilities heretofore applied to rulers to enable them to be chucked in the chuck arms of protractors. 4"The principal object of the present invention is to provide improved chucking or holding of 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 along the top of the ruler. In order that the ruler may be reversed, these chuck plates are provided at both ends of the ruler, and these, of course, add to the weight of the ruler,A and,

l as the chuck plates are located on top of it, they interfere somewhat with the use of the ruler, particularly when the rulers are in the form of scales, and they detract from the appearance of the article.

A11 'these disadvantages are overcome and `'the advantages or objects stated above are attained very effectively by the present invention, which may be'here briefly summarized as consisting in certain novel details and combinations which will be described in the specification and set forth in the appended claims.

In the accompanying sheets of drawings which Show the preferred embodiment of the invention, f t

Figure 1 is atop planv view of the ruler with portions broken away, this ruler being in the form of a scale; I

nFig 2 is a bottom view of the same;

Fig. 3 is a cross-sectional View of the same on an enlarged scale;

"Fig, 4 is a similar view of the scala-the section being taken through one of the chucks 0f the scale and through the chuck arm; and n 5.is a plan View of a protractor with two rulers, portions only of which are'shown, held on the chuck arms at right angles to each other.

YReferring, to `the drawings, the ruler shown therein includes a metal stiffening core lll and a suitable non-metallic covering H, such as cel- Iuloid or pyralin, which encloses the core and is of course tightly fitted thereon. The core lll is preferably formed by extruding and drawing processes from a suitable light but stiff metal, such as duralumin or magnesium alloys. In the preferred way of producing the core, a strip having the approximate cross-sectional shape of the core and of suitable length is extruded and is then passed through drawing dies in which the desired cross-section is obtained. It is then placed in a stretching machine to straighten it as much as possible, and after cores of proper lengths for use in the rulers have been cut from the strip, the cores are subjected to a further straightening operation by subjecting them to severe pressure in a press between dies which are 'shaped in conformity with the shape of the core.

'I'he covering is preferably applied by heat and pressure in a mold, as described in my United States Patent No. 1,728,420, the covering of course, enclosing the core, including the top and bottom surfaces and the ends, although certain portions of the covering on the center line of the top are later removed to accommodate the heads of screws which hold the chucks to the under channelled surface of the ruler. The rulers may be in the form of scales or straight edges, but if in the form of scales, the top will usually be beveled along both sides and the beveled surfaces will be provided with the usual graduations and characters. If the ruler is in the form of a straight edge, the bevels will usually be omitted from the top surface of the ruler.

According to the provisions of the present invention the ruler is provided on its lower side and extending centrally from end to end with a channel which I prefer to be somewhat greater than one-half the width of the ruler and that its cross-section be approximately one-third of the cross-sectional area of the ruler. The top wall of the channel is, of course, parallel to the top of the ruler and its side walls are slightly tapered.

This channel has numerous functions, and has utility both in the production of the core and the ruler as a whole and in subsequent use, particularly when chucked in protractors such as form a part of the drafting machines. Perhaps its greatest utility lies in the fact that it admits of a greatly improved method of and means for chucking the ruler, but this will be referred to presently. Among the other advantages utilized in the manufacture of the ruler and in its use independently of protractors and the chuck arms thereof might be mentioned the following. The channelled section of the core increases greatly considerablyrless Weight if vmetal of the same kind is employed.

The channel is useful in producing the core itself for it enables me to produce cores free of twists and bends which was not always the case with the unchannelled cores. AI-Ieretofore I experienced considerable diculty in obtaining cores which were truly straight. In producing a quantity of cores, a portion of them would be.Y

straight when produced by the methods described above, but others would not be so, but

when I produce these channelled cores byirst,V

extruding the strip, passing it through a drawing die, stretching the strip, and then after theV strip is cutV into core lengths subjecting them to pressure between dies in aupress, the coresare uniformly straightv 'to' an extremely vhigh 'degree of accuracy. 'Ihis result is Vobtained because by utilizing straightening dies, the lower one of which is provided with a part which conforms to the shapeof Vthe channel' and of course extends forits full length, ther` upper die. of Ythe press, when 'it strikes the core which is'easily correctly placed and vheld on the lower die with said'part filling the channel, removes theflast vestige of 'any twisting or bending distortion, with the resultthat thecores are produced uniformly straight. Finally, itlper'forms a very useful function in that part `of-theprocessl of forming the rulers wherein the non-metallic covering is molded by heat and pressure around the core. In this connection' it'might be statedfthat previous to the conception ofthe channelledcoreV difficulty was encountered by'me VinIkeeping the core central and inV keeping it from bendingwhen subjected tothe enormous pressure necessary in molding thefone-'piecezunitary covering around the core. In producing a quantity ofrulers, the coresof someof them would beproperly positioned but notl soof others. I found that'in some instances thecores hadLa' tendenc'y'tol float, so to speak,'infthe celluloidso that they would'fnot be centrally positioned therein. To overcome this, I `attempted to hold the core in position by spaced pins engaged in openings of the coregbut this Yexpedient would not Ysuffice in some instances for the pressure of Athe' Celluloid on the core seemed to bend it.Y Thes'erdi'iculties areentirelyfovercome by the'channelled corelfor I find that in molding the non-metallic plasticmaterial'around thecore `with aY rib on the lower mold member extending for the 'full length into thechannel,

the shifting ofthe core in fthe moldand the bendingiof the corearereliminated soA that in the production of a'qua'ntity of these rulers they are substantially uniform in the'desired centralized relationship of the core in the Celluloid or other covering material.

i .A greater'advantageY of the channelled rulers lies'in 'the` fact that byy reason. of the channel I am enabled to chuck the ruler'on the chuck holding arm of a protractor with the-chucking belov'vvtlfiev top v'surface of the ruler, in fact on the -under side. thereof# For the accomplishment of this I provide onthe under side of the ruler' and against ther upper wall ofthe channel aplurality of independent chucks which Vare adapted to engage and interlock with the chuck arm which is 'extended into the channel and confrmssubstantially. to the Ycross-sectional shape thereof, Vthe chucks being so `formed that they f arms. The form and location and the manner of securing the chucksin the channel are well illustrated in Figs. 2, 3, 4, and 5, wherein the,

inch, I prefer to employ Ythree chucks at each end,V these chucksrbeing equally-spaced. Each chuck is formedfrom a piece of metal slightly f willengage insuitably formedslots in the chuck elongated in form with flat sides I?.ar (Fig. 2)

slightly tapered, being Yslightly convergent .1to- Ward the adjacent end of the ruler, i. e., toward the protractor in which theyV are to be chucked.

Likewise,A the walls 'forming'i the 'at sides are slightly tapered toward the top' fthe channel; as shown at YI'Sllin Fig'. 3. Each chuck isheld in rplace against'the upperwall of` the channel and centrally of the latter by asniall screw I 4v which extend longitudinally of the ruler and are through an opening in the ruler, which' opening is somewhat larger'thanithe `shank of .the'screw so that the screw, and thereforey the-chuck,may be adjusted in any'idirection. ,'Ihev head Ill,a of the screw, which' is preferably rflatand circular and of a thickness only-very slightly, if any,-

greater than the thickness ofthecoveringon the core, bears against ,the core, as'clearly shown." Y y in'Fig. 4, the covering being cut away'soias-td provid-e clearance for the head. K Obviously,lwhenVV the screwzis tightenedythe chuck isydrawnup tightly against the Vupper wall off-.the,charlnel,V and prior to tightening it, the chuckican begivenY the desiredpositioning so that .it'will properly fit therslot in -the chuck'Y arm. Thisl method-5 of chucking is especially well adapted for quantity production.l

` In Fig.f5 I have shownrhowuthe' chucking is ac- 'n complished. I- have here shown rather conventionally a' protractor which formsthe subject matter; of a: companion application jSerial No.

526,912 filed 0f evendateherewithi: It Will'tle suicient to `state that this protractor includes a protractor plate I6 which is pivoted to the center ofi and is rotatablevwith respect to` a notchedv holdingrplate I'I. chuck arm plate I8 havingtwo chuckV arms I9 and 26 to which the rulers are adapted-to be chucked, these arms being. as usual atright angles to each other. A protractor of this kind is generally-secured to the parallel motion mechanism of za drafting machine, the notched plateA il having ,extensions I'leby which this mayy be brought about; Additionallyftheprotractor has a centrally located handle ZI which is grasped by the operator when the protractor plateyand rulers are to be turned',- and there is Vsupportedin Athis' instance by the .chuck-arm Vplate I8 `a ratchet p-awl 2la thenose of whichY is adaptedV to. snap into, the 4notches of Vthe`fnotched plate`V I-'I .to

position the protractor whenvit isturned .andto rulers of different lengths.V A These chuck arms in cross-section conformto the cross-sectionl ofthe channel and theyare' adapted to ,extend into the 50 The protractor includes alsoa channelsv of' thei'rulers .when the latter-' are chucked athereto. '.The thickness of. the chuck armsis aboutthesame or slightly'less thanthe depth' of Afthe 'channelsfas indicatedin" Fig. 4. Each of these chuck arms a pluralityof slots 23 whichextend transversely through the chuck arms centrallythereof, which slots fare adapted to receive the chucks I3 of thecorresponding ruler. The number' of these slots will'depend upon the number of chucks'withl which the ruler is provided. That is to say, for a rulerhaving two chucks at each end, the chuck arm will have two of these slots, asshown-lin the-shorter chuck armfz'lS. lIf. the ruler has three or more chucks at each end, the chuck arm will have a corresponding number 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 narrower ends of the slots being preferably 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 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 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.

Thus, with the chucking means 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 drawing 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 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 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 instrument as a whole. Either or both of the two chucks (or three if three are employed) can be independently adjusted so that perfect alignment can be obtained and to bring about equal bearing action of both sides of the chuck on the chuck arm, it being understood that the chucks have the necessary lengthwise and crosswise adjustment to attain these ends. Finally, it might be stated that a plurality of chucks formed and spaced apart as illustrated and described do not have the disadvantage of a single relatively long chuck in 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 detriment of accuracy.

From the above it will be seen that the crosssectional shape of the composite ruler has advantages independent of those which flow from the new chucking features. It will be seen also from the above that the use of two or more separate chucks at each end of the ruler in- 3 stead of asingle long chuck has advantages 'regardless of whether the chucking is done on the under side of theA ruler or on the top." Thearrangement of the separate chucks in the channel and the method of chucking herein-described are preferred, but I regard it within the scope of-my invention to use chucks similar `to those described but mounted on'the top surface of the ruler with the heads of the screws in the channel, in 'which event the chuck arm will extend over the ruler and engage the chucks as before.

It will `be seen from the above that my improved channelled ruler' either in the form of a scale or a straight edge has numerous advantages-in per'- mitting an increase inthe stiffness and a reduction in weight, and facilitates the manufacture of composite rulers having a metal core and a covering of Celluloid or the like, and, together with the chucks preferably secured in the channel, permit a greatly improved method of chucking 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 confined 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 employed. 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 andthe chuck arms would extend over the ruler and engage the chucks as before, but, of course, with that arrangement only part of the herein-mentioned advantages would be attained as compared with the preferred construction, and therefore the preferred method of chucking herein described and illustrated.

While I have shown the preferred construction, I do not desire to be confined to the precise details as changes may be made without departing from the spirit and scope of the invention, and I therefore aim in my claims to cover all such modifications.

Having thus described my invention, I claim:

1. A ruler adapted to be connected to a ruler supporting arm of a drafting machine, said ruler having a channel in one side thereof to receive the ruler supporting arm, and a chuck secured in said channel for chucking said ruler to the ruler supporting arm.

2. A ruler adapted to be chucked to a ruler supporting arm of a drafting machine having a channel on the lower side thereof to receive the ruler supporting arm, and a tapered chuck secured in said channel for chucking the ruler to the ruler supporting arm, means extending from the chuck and exposed at the upper side of the ruler.

3. A ruler adapted to be chucked to a ruler secured to and independently adjustable on the ruler. 1 j A 5. A composite ruler adapted to be chucked to awsupporting arm comprising a stiiening core having a channel in one side-thereof Yand a nonmetallc covering Vmoldedto the core and conforming to the shape of Athe channel whereby a channel is formed in the side of the composite ruler adapted to receive the supporting arm, and a chuck secured in the channel of the rulervfor chucking the ruler to the supporting arm.

l 6. A ruler adapted to be chucked to a ruler supporting arm of a drafting machine having a channelin one side thereof adaptedv to receive the ruler supporting arm, and a plurality of,

tapered chucks secured to the ruler in said channel for chuckng the ruler tosaid supporting arm.

. covering enclosing saidY core. and Vconforming thereto, said channel being adapted to"A receive a supporting arm, andxa plurality of chucks secured in said channel and adapted to engage said supportingarm. 1V c Y 8. A ruler comprising a core,;a nonj-metallic covering enclosing said core. said ruler being provided with Aa channel on the lower side thereof and an opening extending from the vtop of Vthe rulerV to the channel, aY chuck in' said channel, and a screw extending through said opening for holding said chuck. Y

CHARLES H. LITTLE. Y

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