US2129457A - Drawing board - Google Patents

Description

Sept. 6, 1938. M. K. voNzlMMx-:RMANN DRAWING BOARD Filed sept. '26, 1955 4 Sheets-Sheet l N @www Sept- 6, 1938. M, K. voN ZIMMERMANN 2,129,457

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M. K. VON ZIMMERMANN DRAWING BOARD Filed sept. 2e, 1955 4 Sheets-Sheet 4 .NN @pmx Patented Sept. 6, 1938 UNITED vSTATES PATE-NYT oFFicE 2,129,457 DRAWING BOARD Max Kurt von Zimmermann, Elkhart, Ind. yApplication September 26, 1935, Serial No. 42,338

4 Claims.

This invention relates to a drawing board, and more particularly to a drawing board having means for clamping and stretching the paper thereon.

One feature of thisinvention is that it provides means for clamping the edge of a sheet of drawing paper throughout substantially its entire length; another feature of this invention is that the clamping means are below the drawing surface thus presenting no obstruction to free movement of a triangle, protractor or other tool over the whole drawing surface; still another feature of this invention is that the clamping means is positively operable; still another feature of this invention is that the clamping means may be moved outward slightly from the drawing surface in order to stretch the paper; yet another feature of this invention is that apermanently aligned parallel straight-edge is attached to the board; other features and advantages of this invention will be apparent from the following specification and the drawings, in which- Fig. l is a top plan view of the board; Fig. 2 is a vertical elevation of the top of the board; Fig. 3 is an elevation of the bottom of the board; Fig. 4 is a sectional vie-w along the line 4-4 of Fig. 2; Fig. 5 is an end view of the board; Fig. 6 is a view along the line 6-6 of Fig. 1; Fig. 7 is a view along the line 1-1 of Fig. 1; Fig. 8 is a horizontal sectional view of one end of the board; Fig. 9 is a View along the line 9 9 of Fig. 8; Fig. 10 is a View along the line IIl--I Il of Fig. 8; Fig. l1 isa view along the line II-II of Fig. 8; Fig. 12 is a sectional viewr y and keep it taut on the drawing surface of the board. The clamping and stretching means are provided with manually operable slides, but the stretching means is spring pressed so that the paper cannot be torn through the application of too strong a pull. The board is also provided with a parallel straight-edge, which straight-edge is so mounted as to be movable across the surface of the board and yet be maintained in proper alignment.

Referring more particularly to the drawings, the reference numeral I5 indicates the drawing board in general. The board has a drawing surface I6, and immediately adjacent the edges thereof clamping means I1 and I8, which means are operated by the slides I9 and 20, which slides are here shown as terminating in finger grips ZI and 22 located in recesses 23 and 24 in the board I5. Springs 25 are inserted between the drawing board I5 and the clamping means I1 and I8, respectively, and-I the stretching action of these springs is controlled by slides 26 and 2l having finger grips 28 and 29, these last mentioned finger grips lying further within the recesses 23 and 24, as is illustrated in Fig. 1. A straight-edge 30 is movably carried byv straight-edge supporting means 3l and 32 attached to the clamping and stretching means Il and I8. The straight-edge 3U is attached to the chains 33 and 34 by any convenient means, as by the bolts 35 and 36. These chains are .carried by sprockets in the straightedge supporting means, and are connected by the transverse shaft 3l located in the housing 33 at the top of the board.

The connecting means `between the chains 33 and 34, as particularly illustrated in Fig. 4, serves to insurev a ycorresponding motion in the chains whenever the straight-edge is moved upy and down the drawing surface of the board. It will be noted that the chains 33 and -34 are carried at their upper ends by lsprocket wheels 39 and 40, which wheels are journalled in bearings 4I and 42. Inasmuch as the construction on opposite ends of the connecting shaft 3l is similar, only that at one end will be described in detail. The sprockety39 is rigidly attached to a stub shaft 43, which shaft is non-rotatably slidably splined, at its inner end, to the. assembly of sleeve 44 and connecting shaft 3l. The shaft 31 is journalled at this end in the bearing 45, and is restrained from lengthwise movement by the cooperation of this bearing with the sleeve 44, and the similar assembly on the other end of the shaft, since the inner faces ofthe sleeve 44 act as thrust bearings. This construction enables the straight-edge supporting member 3 I to be moved outwardly from the lboard a short distance during stretching of the paper without in any way disturbing the operative connection between the chains 33 and 34 through the shaft 31. It is to be understood that at least one end of the straighty iok clamping member or jaw 41, these two clamping members being adapted to grippingly retain the edge of a sheet of drawing paper 48.

The construction and operation of the clamping and stretching means will be more readily understood from a description in connection with Fig. 8. The frame 49 is attached to the board I5 by screws 50 threaded therein. The screws 50 are inserted through the openings 5I, 53, 55 and 13 and are `not driven in tight against the board, a space 52 being left between the frame 49 and the edge of the board I5. Yielding thrust members, here illustrated as coil springs 25, are:

mounted in recesses 54 in the board I5. As will be noted from Fig. '1, these springs are mountedl immediately adjacent the screws 50, but in staggered relation thereto. This staggered relation, wherein some of the springsl press against the frame 49 above the level of the screws 50 and some press against the frame below that level, serves to keep the frame and clamping means in properalignment with the board, and to: prevent them from twisting under the strain of stretching the paper. Positive means for keeping:

the clamping means in proper alignment with the board can be provided by adding guide pins to the frame of the clamping means and corresponding guide holes'. in the board, or by other convenient means. Thisconstruction, wherein the paperv is stretched over the drawingV surface by spring pressure rather than by positive means, has several advantages. Shrinkage or swelling of the paper due to changes in temperature or humidity of the surrounding atmosphere is automatically compensated for by movement in and out of the clamping means, for example, against the outward thrust 'of the springs. The usual holding means, such as thumbtacks, staples, Scotch tape, and the like, are open to objection in this regard in that atmospheric changes either cause the paper to buckle or -to tear.

The heads of the screws 58 engage the slide 26, the screws themselves passing throughv slots 55 in said slide. The slide 26 is provided with ears 56, which ears are adapted to extend into slots 51 in a channel bar 58r inside of and anchored to the frame 49. The channel bar 58 is a snug iit within the frame 49, and is anchored in place and prevented from lengthwise movement by having ears or tabs 14 punched outwardly` through the holes 53 in the center vertical wall of the frame 49, which holes also serve to clear the heads of the screws 59 when they are removed. Referring to Fig. 8, the method of anchoring the channelbar'may be clearly seen in connection with the opening 53 back ofthe head of the screw farthest to the left in the View. The slots and ears are inclined at a-convenient angle,

here shown as about seven degrees, which slots are so arranged that pushing the lnger'gr-ip 281 into the position shown in dotted lines in Fig. 8, through the engagement of the slide ZB'with the heads of the screws 5I), causes the entire frameY 49- and clamping meansI I1 to move inwardlyto aposition substantially in contact with the edge of the board I5. When the-slide is pulled out untilv the finger grip.A 28 is in the position illustrated in Fig.v 8, the slide 26 moves away from th'e'heads of the screws 50' and enables thespringsv 25- toi force the clamping means I1 away from the board and thus to stretchthe sheet of paper 48, shown in Fig. 1'2.

The clampingmeans, comprising` the 'clamping' member 41 and the clamping surface 46- ofthe grip 2I. The slide I9 has therein angularly disposed slots 59. These slots 59 extend longitudinally of the slide, but are inclined at some slight convenientl angle, here shown as about three degrees. The vertical portion of the clamping member 41 has projections 60 and 6I cooperating with each of the edges of each oi the slots 59. Inasmuch as the clamping member 41 is free to move vertically, but is restrained from horizontal motion through the projections 62 extending tion of the clamping member 41, longitudinal movement of the slide I9 results, through the action of the slot 59 on the projections 60 and 6I, in positive upward or downward movement of the clamping member or jaw. When the finger grip 2| on the slide I9 is in the position illustrated in dotted lines in Fig. 8, the clamping member 41` is raised a short distance above the clamping surface 46- of frame 49. When the slide I9'is pulledv out until the finger gripv 2I is in the position illustrated in Fig. 8, however, the upper clamping member or jaw 41 is brought down into positive clamping engagement with the surface top of the clamping member or jaw 41 is slightly below the level of the drawing surface I6 on whichy the paper lies. This permits unobstructed movement of a triangle or other drawing tool when working near the edge of the paper.

The` straight-edge supporting member 3I is attached` to the outer portion of the frame 49 of the clamping and stretching means. Referring more particularly to Fig. 8, it will be seen that the means 3| has openings 64 therein through which screws- 65 are inserted and threaded into a retaining bar 66' lying within the frame 49. The straight-edge supporting means 3| is thus readily removable from the board, since removal of the screws 6.5 enables the supporting means 3I to be taken off, the slidably splined stubbed shaft 43' slipping out of the collar or connecting link 44. The lowerchain sprocket 61 is journalled in ai slidablebearing 68, in order to take up any slack which' may occur in the chain 33. The

straight-edge supporting means or frame 3| is r provided witlr shoulders 69 against which rest av plate 18. n adjustment screw 1I is threadeddotted lines in Fig. 8. The clamping member 41 is thereby raisedlr from the clamping surface 46,

and the entire clamping means isl held immer diatelyf adjacent to the: edge ofthe drawing board I5. A sheet of drawing paper 48 is then placed;

on the-'board and itsopposite ends -slippe'd intof'the clamping means-between the members 45and 41,

for example. Theslid'es I9 and ZUare then pulled outwardly to the positions illustrated in Fig; 1,",

which brings thel clamping" members'positively" The iinger'grips-` 2I, 22, 28V and 29A are pushedI inwardly, to the positions illustrated in down into engagement with the paper and clamps the paper firmly against the clamping surfaces. The slides 26 and 21 are then pulled out to the positions illustrated in Fig. 1, and the pressure of the springs 25 against the frame 49 then pushes it outwardly until the paper 48 is stretched to a tension equal to that of the springs 25. The paper is thus stretched smoothly and tightly over the drawing surface, and is ready for the draftsman. It will be noted, with particular reference to Fig. 12, that the bottom of the frame 49 and the straight-edge supporting means 3| are not flush with the bottom of the board l5, but slightly higher. These parts do not rest on the table or other surface on which the board is placed, but are completely carried by the board at all times. Proper freedom. of movement for stretching is thus assured.

The straight-edge 3l) may be left at one end of the board, out of the way, or it may be used in drawing. Where desired to move the straightledge up or down, it is only necessary to grasp either end, since the connecting shaft 31 and the chains 33 and 34 assure equal motion of both ends of the straight-edge 30. Where it is desired to use the clamping and stretching means only the straight-edge and supporting members 3| and 32, and the connecting shaft and housing 38 may be removed from the board.

While I have shown and described certain ernbodiments of my invention, it is to be understood that it is capable of many modifications. Changes, therefore, in the construction and arrangement may be without departing from the spirit and scope of the invention as disclosed in the appended claims, in which it is my intention to claim all novelty inherent in my invention as broadly as permissible, in view of the prior art.

What I claim as new, and desire to secure by Letters Patent, is:

1. A drawing board of the character described,

including: a drawing surface; clamping means adjacent said drawing surface, said means including a clamping surface, a slide member, and a vertically movable jaw member adapted to clamp substantially the entire edge of a sheet of paper in contact with said clamping surface; a slot in said slide member, said slot being at an angle to the motion of said slide; and a projection on said jaw member extending into said slot, whereby longitudinal movement of said slide effectuates positive vertical movement of said jaw member.

2. A drawing board of the character described,

including: a drawing surface; clamping means adjacent said drawing surface; spring means for moving said clamping means away from said drawing surface, whereby a sheet of paper held in said clamping means is stretched; and manually operable means for holding said clamping means immediately adjacent the edge of said drawing surface, said last mentioned means including a slide having diagonal slots therein adapted to cooperate with members on said clamping means received by said slots. 3. A drawing board of the character described, including: a drawing surface; clamping means adjacent said drawing surface, said clamping means being manually operable by means of a slide; spring means for moving said clamping means away from said drawing surface, whereby a sheet of paper clamped in said means is stretched; and means for holding said clamping means immediately adjacent the edge of said drawing surface, said means including manually operable slide means.

4. A drawing board of the character claimed in claim 3, wherein both of said slides have their tips extending inwardly o-f said clamping means and within a recess in said board.

MAX KURT VON ZIMMERMANN.

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