US2351031A - Draftsman's tracing board - Google Patents

Description

June 13, 1944.l G. E. FRoELlcH DRFTSMAN S TRACING *BOARD Filed 'March 6, 1942 2 Sheets-Sheet 2 Patented June 13, 1944 UNITED PATENT OFFICE".

2,351,031 DRAFrrsMANs TRACiNG BOARD George .Fro'elick Two Rivers, VWis., assgnor to Hamilton Manufacturing Company, Two Rivers, wisaafcorporation of Wisconsin Application-Martire,1942, serial No. 433,615

5z-oiaime (Cl. 45-13L2i t This invention:relates to a tracing board? for use by engineersiand draft's'men fori tracing me'` chanical drawingskr from the. original' usually heavyv paper sheetsV toA transparent tracing cloth or'the like.

The invention aims, amongl othenobjects; to provide a relatively large shallow board forv this purpose adapted to house therewithin fluorescent tube lighting means and a reiiector'element about the lighting means including a plurality of curved surfaces having diierent radii, whereby to enfhance the diffusion of'light" through the'v tra-Ins lucent top panel oftheboard; while-minimizing the sapce occupied.

In one aspect, the tracing board off the pres'- ent invention is markedly adapted to portable form and to be readilymovedr about' bythe draftsman to` suit his convenience and to be placed, when desired,v upon a` conventionaly inclined drafting table for-quick and handy'use.

These andv other objects and advantages will be apparent from the following description; taken together with the` accompanying, drawingsfin which- Figure 1 is a perspective view of'aconventional drafting table with the tracing boardiofthe-pre'sent invention associated therewith; Figure 2 is an enlargedV plan View ofthe tracing boardv with parts broken away for convenience of description; Figure 3 is a section. taken onthe line 3L-3' of Fig. 2 but with the lamp tubesL removed; ,t

' Figure 4 is a fragmentary side elevational view ofthe .tracing board further enlargedandtaken on the line 4-4 of Fig. k2; 'and` y Figure 5 is a still further enlargedfragmentary Asection taken on the line 5--5 ofFig, 2'..

Referring inA detail to the illustrative construe.- tion shown in the drawngsand turning'rstto Figs. 2 and. 3, the tracingboard ofi the present invention, indicated. as a whole by thenuineral I0, is in the form of a relatively large, shallow casing made up vof a flat translucent top panel inember I I, areector element I`2`tlrierebeneath, anda frame I3 for these parts,.which.maylbe of wood, suitably jointed, as neednot be herespeciflcally described. Y The vframe I3 compris'esa rear wall I4, a forward wall I5 anda pair of sidewalls I l., The

rear wall I4Y an'dforward.- wall I5 are extended.

horizontally toward each other iny overhanging portions I'I and irespectively and are rabbete'd at their adjacent edges. asat Illa-nd 20- to receive ,thetranslucentpanel IV flusnwith thetop. sur- A face of' the frame members Hand I8`an`d also with the side members' I6. The sidewalls Ill'may also be rabbeted for this purpose as atv Ita in'their overhanging portions ISU. Sinallat metalV clips 2I at each corner of the translucent panel,'se cured as by screws 22 to the frame, hold the panel tI in place. The translucent panel is desirablya rel'ativelythiclry crystal glass sheet having its lun der surface 23 sand blasted to aid in the diffusion of light directed therethrough, as presentlyfur ther' referred to, in more particular'detail.

Along boththe rear andforward` inner margins vof the frame I3 and under the'overliangin'g auxiliarytop panels I1 and I8'of the frame are located a pair of fluorescent lamp tubes 24 mounted on the usual metal biackets 25 there for at each corner ofthe frame, The rear-most of` the tubes 24 is conveniently spaced slightly farther from the framev rear wall I4 than is the forwardl tube 24 from the forward frame wall I5, so as to provide space between the wall I4 and its adjacent'tube 24 for the usualelectrical starting and'ballast devices for thetubes which may tbe housed as in metal boxes' 26, 21, 28 and 29.

Since Ythese starting andv ballast devices are conventional "they need not be here described, it being suiicient to say that the wiringy (not shown) for the tube sockets '25for thetwo tubes 24 respectively may be in parallel, with the usual nductance, and iii-metallic switchv` contacts, vas wellas the usual inductance and capacitanceffo'r one of the tubes, the greater part of which may beenclosed within the boxes 26, 21,' 23 andZ'S. The rearwall I4` may carrya lead-in' conductor cord: 30, for pluggingin A tojtheusual wall elec"- tricalA outletl or the like forA. C. current, anda main .switch 3i for the board circuit isxalso mounted on this rearwall. `The wires-for the forwardA fluorescent tube may` be run` along the side walls I6H of the casing just beneath the over-- hanging walls Ib; The tubes '24' may' contain the usual vapor and have a fluorescent chemical coating' onv their inner surface by -which the waves of electrical energy sent through the-tubes are converted into visible light, as-is well known in theart By the electrical devices -generallyf indicated, one of vthe lamps V24 balances the other electrically, so as to produce, to the-eye, afsteady light, and by means of the. arrangement here shown, the light is originated along bothy the rear and forward margins ofthe board, so as to providev enhanced distribution of thelight .to all parts of the board. l

Further in accordance with the present invention, al reflector element l2.v for the-.lamps 241s uniquely provided. This reflector element may 2 ,il i

low, trough-like form, to meet angularly as at 341 y along a medial line extending across 'the board -i parallel with the top panel and spaced there4 below. The ends of the reector cylindrical portions are serviceably notched'as at 32ato,=pre4 bracket-$52.5

vent interference with the Ymounting for the lamps. i

The formation as just described of the reflectorl l element l2 is advantageously effected by providing, on'each of the inner faces of the side walls .f6 of the board, an offset cleat 35 which may be also of wood and secured to the side wall I6 as by screws 36. The lower edges of the cleats 35 are serviceably shapedas Yat 3l to conform to the contour lof the trough-like portions 33 of the ref'V flector element which latter are secured to these loweredges of the cleats as by. screws 38,thus maintaining the reflector, element in its desired shape. y

The arrangement of the reflector element, here shown and described, desirably produces a pluralityof curved reflector surfaces having different radiLYthe radius of the cylindrical portion32 differing materially' from the .radius of the troughlike lportion .233 .and thus an enhanced number `of the rays of light from each lamp 24 Yare controlledand directedto a useful purpose .throughthe translucent panel. I I. Furthermore, the ,lamps and curved surfaces being impairs, rays of light from one pair, .which might otherq wise be lost, are caught and usefully directed .by thek other pair, all while at the same time main.-4 taining the board and itsY contents within a I elatively shallow or sho-rt vertical distance. Ari-important result of theshallow dimensions of theboard of the present invention is that it vmaybe placed on topof an ordinary drafting table as indicated 4in Fig. l, which table may haveA the usual base 39 and a slanting adjustable top. 4I), as is well known in the art. In order to -hold the board of the present invention on the slanting top 40, particularly when this top may be somewhat acutely` slanted, hanger means are here provided and which `are shown in the form of aa'pair of adjustable rods V4| carried by the board 'along the. outer faces of its side walls 6. andadjacent the rear. margin of the board.:

A'rod 4|, 'as best shown in Fi'g.4, is slidingly clamped to the side wall 6 as by a pair of clamping brackets-42, having somewhat cylindrical portionsprovidingbearings for the rod. By loosen; ingand then tightening the screws 43, the vrod 4| may be adjusted longitudinally with respect t'o the board so as to suit different sizes, or widths, of table tops 40. The 'rods 4| at their rearward ends haveV downturned terminations 44`which' extendbelow the lower surface of the board to hook over the rear edge 45 of the table' top 4B. At their other ends, the rods 4| may also be downtured as at 46 (but without projecting below the lower surface of the board) yso as to engage a stop screw 41 to limit retraction of the rods and thusprevent accidental removal from the board. When not in use the stop rod 4| may be rotated to the position shown in broken lines in Fig. 4

to avoid interference with other objects.

Adjacent its rear and forward lower face margins, the board may carry thin strips 48 of bre rcomposition or other non-metallic material so as to slightly elevate the reector from the table top 40 and prevent scratching of the table top thereby, while affording a smooth and stable rest surface fo'rthe board.

The board I0 may advantageously be provided with a handle 49 of leather or the like secured as A'by clamp-sockets 50 to the rear edge of the board and elongatedv in the direction of this edge so that vthe board may be conveniently carried about to be placed upon or removed from the table top 40. Also, when not in use, the board may be "stoodo'nedge, along its forward wall I5, with the handle uppermost, so as to occupy a minimum of space and at the'same time be readily grasped when desired.

, Soyconstructed-and arranged, the board Vof the present inventiony effects a maximum of Iefficiency with a.' minimmof constructionand mainte#- nance expense.v Since .the boards are relatively inexpensiveand require a minimum of space for storage, a drafting room can have several of them on hand, and if a. draft'smanhas intervals of time,availablebetween otherwork,vhe can readily place one of the tracing boards here disclosed on .his vdrafting table and use the time to work on newytracings without leaving his table .while doing softherebyincreasing the productive work of thedraftingrooin.` i

Such changes may be made asfall .within the scope of ,the following ,claims without., departing from,the'invention.` 4

@Having described 'm'yinyentiom I claim: 1. A drafts'mans tracing `board comprisingdn combination, a. relatively. large shallow casing, a` flat `.i ;ransluce `ntl. top panel 1 therefor, lighting means withinthe. casing'. said lightingv means includinga paiiof uorescenttubes arranged along= the rear'` and 'forward inner margins v'of the.lc'as ing,"and 'a reector` element about the lighting means .embodyinaa somewhat semifcylindricai 'portion Vabout each tube, the interiors., of the semi-cylindrical. portions being 'in opposed l relation and their lowerj ends being continued .toward 'each other in shallowtrough-like lfornito meet angularly along 'a medial line 'extending across the, board parallel with the rtop p an'el andspaced therebelow whereby to, enhance the distribution Q f light, "throushj the msaidv topwhile minimizing the,space;o'ciipledbytheboard.` 2. A' dr'aftman ytracing "board comprising', in cpmbriatiari- @casina a flat translucent topranl e1fiherror 1ighting means within the casing.

afn@ albnel, opposite inner'walls ofthe' casing, and a reflector element aboutthe lighting means embodying a somewhatsemi-cylindrical portion about each light, the interiors of the semi-cylindrical portions being in opposed'relation and their lower ends ,being continuedjto-,L ward eachl other in trough-like form to meet angularlywalong a I riedialq line extending across the. boardparallel with thegtop panel and spaced,- therebelow whereby to enhance-the, distribution of lightA throughmtlhe said top whileminimizing the space occupied by the board, Kwherein the boardcarrine's on each of the inner Afacesofthe said walls'jan elementA having` itslower edge coa. formed tothe c ontourof ,thereflector portions and to Which'the reector portions are securedV to'maintainithesa'idrelationship ofthe latter. l 3; Adraftsmans tracing board comprising, in

combination, a relatively large shallow casing of generally rectangular dimensions throughout, a flat translucent top panel therefor, lighting means within the casing, said lighting means including a pair of iiuorescent tubes arranged along opposite inner margins of the casing, a cleat secured along the inner face of each of two opposite walls of the casing, and a shallow reflector element secured to the lower edges of said cleats and including a somewhat semi-cylindrical portion about each tube, the interiors of said semi-cylindrical portions being in opposed relation whereby light is reflected from one to the other of said semi-cylindrical portions to enhance the distribution of light throughout said casing while minimizing the space occupied by the board, the said lower edges of said cleats being conformed to the cross-sectional shape of said reector element and maintaining said shape.

4. A draftsmans tracing board for use with a drafting table or the like having an inclined top comprising, in combination, a relatively large shallow casing of generally rectangular dimensions throughout, a flat translucent top panel therefor, lighting means within the casing, a shallow reflector element about the lighting means, a pair of extensible rod members carried one along each side of said board and having formations adapted to hook over the rear edge of `Said table top to support the board thereon in slanting operative position, and somewhat cylindrical bearings on the casing for the` members, said members being selectively slidable and rotatable in said bearings to bring said formations into the plane of the casing and into close proximity therewith when not in use.

5. A draftsmans tracing board comprising, in combination, a relatively large shallow casing of generally rectangular dimensions throughout, a ilat translucent top panel therefor, lighting means within the casing, said lighting means including a pair of fluorescent tubes arranged along opposite inner margins of the casing, a shallow reector element about the lighting means `embodying a somewhat semi-cylindrical portion about each tube, the interiors of said semi-cylindrical portions being in opposed relation, the lower margins of said semi-cylindrical reiiector portions being continued toward each other in shallow trough-like form to meet angularly along a medial line extending across the board parallel with the top panel and spaced somewhat therebelow whereby rays of light are reflected from one to the other of said semi-cylindrical portions to enhance the distribution of light throughout said casing.

GEORGE E. FROELICH.

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