US2936524A - Drafting machine - Google Patents

Description

May 17, 1960 E. J. SHAFFER DRAFTING MACHINE Filed July 24. 1958 INVENTOR. Earl J. Shaffer BY /gJJ 311ur7 HIS ATTORNEYS United States Patent DRAFTING MACHINE Earl J. Shalfer, Homestead, Pa.

Application July 24, 1958, Serial No. 750,756

2 Claims. (Cl. 33-76) This invention relates to improvements in drafting and drawing machines for use on drawing boards, tables, layout machines, and the like, and the primary object of my invention is to provide a versatile machine which can be easily and efiiciently operated by a draftsman.

Many drafting machines are known which have guide rails mounted parallel to one edge of a drafting board and a roller mounted straight edge movable along the guide. These known machines are of complex construction and thus difiicult to repair, clean and adjust. thermore, some lubricated parts on these known machines are exposed, thereby causing untidy drawings due to a draftsman inadvertently contacting the lubricated parts with his clothing and subsequently contacting the drawing being prepared with the same clothing. I

My invention avoids the above ditficulties by providing a drafting machine of simple construction, easy to repair, clean and adjust. All lubricated parts of my invention are enclosed, thus avoiding inadvertent damage to drawings.

In the drawings I have illustrated a present preferred embodiment of my invention in which:

Figure 1 is a plan view of my machine;

Figure 2 is a cross section of my machine taken on line 11-11 of Figure 1; and

Figure 3 is a cross section of my machine taken on line III-III of Figure 1.

Briefly, the present invention comprises a hollow tubular guide alfixed along and parallel to the edge of a drawing board and a straight edge movably mounted over the drawing board and afiixed to bearings rotatable within the tubular guide. A slot is provided in the tubular guide to permit vertical movement of the straight edge relative to the drawing board for purposes of cleaning the apparatus and movement over obstructions positioned on the drawing board. The straight edge is pivotally mounted on bearings affixed to a head plate having a protractor thereon such that the straight edge may be locked in any one of a plurality of predetermined angles.

Referring more specifically to the drawings, a pair of C-shaped brackets 5 have upper legs positionable on the top of a drawing board 6 and lower legs which extend under the drawing board and are spaced therefrom. A screw clamp 7 passes through a threaded opening in each of the lower legs of brackets 5 and engages the lower side of the drawing board 6 thereby tightly locking the bracket to the drawing board 6. Rotation of screw clamp 7 brings its upper end into contact with the underside of the drawing board. Brackets 5 are located in spaced positions along the edge of the drawing board 6 and are welded to a hollow tubular roller guide 8. The guide 8 extends substantially parallel to the edge of the drawing board and has its upper surface located a small distance below the upper surface of the drawing board 6. A portion of the top of guide 8 is removed to provide a continuous slot 9 extending the entire length of the guide. The slot 9, as shown in Figure 2, has one edge 10 located a short distance to the light of a vertical plane passing Furthrough the axis of the guide 8 and a second edge 11 located about 45 to the left of the vertical plane passing through the axis of guide 8 on the side of the guide away from the drawing board. The purpose of this slot will be explained hereinafter.

A pair of C-shaped bearing mounting plates 12 and 13 are positioned back-to-back within one end of the guide 8 and a second pair of similar bearing support plates are positioned within the guide at a point removed from the one end. The construction of only one pair of the hearing support plates and hearings will be described herein since both mechanisms are of identical construction. The plates 12 and 13 are generally C-shaped and each has an intermediate plate 14 aflixed midway between and parallel to the upper and lower legs of the plates.

A pair of barrel roller bearings 15 are rotatably mounted in openings in the lower leg of plate 12 and openings in plate 14 afiixed to plate 12 and a second pair of barrel roller bearings are rotatably mounted in openings in the lower leg of plate 13 and openings in plate .14 affixed to plate 13, as shown in Figures 2 and 3. The axes of rotation of the bearings are parallel to the webs of the O- shaped plates 12 and 13.

A set screw 16 is threaded in an opening in the web of C-shaped plate 12 with the inner end of the set screw in engagement with the web of O-shaped plate 13. The tube 3 has at least one opening 17 therein through which a screwdriver may be inserted when the opening 17 is in alignment with the set screw 16 and the set screw tightened by rotation of the screwdriver to force the plates 12 and 13 apart. Moving the webs of plates 12 and 13 apart forces the bearings 15 on each of the plates 12 and 13 into tight engagement with the tube 8. The bearings 15 must be free to rotate at all times however. In this manner, the plates 12 and 13 are rigidly mounted and movable within the tube 8.

Each of the bearings 15 'has a brass washer 18 mounted on each of its axes between it and the supporting plates, i.e., the lower legs of the plates 12 and 13 and the plate 14. Lubrication of the axes of the bearings is necessary to permit free rotation.

A triangularly shaped head plate 19 is affixed to the upper legs of both pairs of plates 12 and 13 by screws 20 which pass through openings in the head plate 19 and are threaded into openings in the upper legs of the plates 12 and 13. A pair of plates 12 and 13 are affixed at each end of the head plate as shown in Figure 1.

A straight edge blade 21 having plastic or wooden edges 22 is pivotally mounted to head plate 19 by a screw 23 which passes upward through openings in head plate 19 and blade 21 and has a nut 24 threaded thereon. The end of the straight edge blade 21 has a continuous slot 25 therein of arcuate shape. A screw 26 passes upward through an opening in head plate 19 and through the slot 25 and has a nut 27 threaded thereon. By loosening the nuts 24 and 27 slightly, the blade 21 may be pivoted on screw 23 to any of a plurality of angles on the surface of the drawing board. To measure and set such angles, the head plate 19 is provided with a protractor scale 28 and the blade 21 has a line 29 inscribed thereon to indicate the angle at which the blade is located when the line 29 is lined up with the angle subdivisions of protractor scale 28.

To operate the drafting machine, the brackets 5 are positioned on the edge of the drafting board as shown in Figure 2. The screw clamps 7 are tightened at each end of the guide 8 and bearings 15 and plates 12 and 13 are positioned inside the guide 8 in the manner shown in Figure 2. The set screws 16 in each of the plates 12 are aligned separately with the opening 17 in guide 8 and a screwdriver is inserted through the opening 17 and turned to tighten the set screws and move each pair of plates 12 and 13 apart to rigidly lock the bearings 15 within the guide 8. The bearings are free to rotate however. The drafting machine is then ready for use. i If it is desired to swing the blade horizontally over the draftingiboard, the screws 24 and 27 are loosened slightly, the desired angle is located on the protractor scale 28 and the blade swung in the proper direction until line 29 is aligned with the subdivision on scale 28 indicating the desired angle. The locking screws 24 and 27.a1'e then tightened to maintain the blade in the desired position.

If it is desired to swing the blade 21 vertically relative to the drafting board, it is merely necessary to pull upward on the blade and it will swing to the dash line position shown in Figure 2. In so doing, the bearings 15 merely slide within the guide 8 to the angular position required to position the blade at the desired vertical angle.

From the above description, it is seen that the only parts requiring lubrication on my invention are the bearings 15. These bearings are always maintained within the guide 8 and there is no possibility that drawings will beinadvertently soiled due to a draftsman contacting the lubricated part with his clothing and subsequently contacting the drawings with the same clothing. It is also apparent that my invention is a simple machine, easy to clean and maintain.

While I have described a present preferred embodiment of my invention, it may be otherwise embodied within the scope of the following claims.

I claim:

1. A drafting machine adapted to be mounted along the edge of a drawing board, comprising spaced brackets adapted to be secured to the drawing board, a tubular guide of circular cross-section affixed to said brackets, the central axis of rotation of said tubular guide extending substantially parallel to the edge of the drawing board, a portion of the upper surface of said guide being removed toform a continuous opening along the length of the guide; said continuous opening commencing along a line about 45 from a vertical plane passing through said central axis and extending to a second line a short distance from said vertical plane and on the side of the plane opposite the side on which the first line is located, said first line being located on a side of the vertical plane remote from the drawing board; a pair of C-shaped plates each having a web and a lower leg positioned within said guide; a portion of the web of each of the -C-shaped plates extending vertically upward above the opening in the guide; the lower leg of each plate extending in opposed directions to each other, an intermediate plate afiixed to the vertically extending web on each plate and spaced from and parallel to said lower leg; a plurality of bearings atfixed to axes rotatably mounted between said lower leg and said intermediate plate on each plate, said axes being parallel to each vertically extending web; said bearings being barrel-shaped to conform to and engage the inner surfaces of the guide such that said C-shaped plates may move longitudinally along the guide and pivot transversely relative to the guide; threaded means to move said vertically extending webs of the C-shaped plates located within the guide away from each other to move the bearings into tighter contact with the inside surfaces of the guide; ahead plate afiixed to the upper ends of said vertically extending webs in a horizontal plane substantially parallel with the surface of the drawing board, and a straight edge to overlie the drawing board and having one of its ends aflixed to the head plate such that the straight edge is movable longitudinally with respect to the guide or swingably upward away from the drawing board. 7

2. A guide mechanism comprising spaced brackets adapted to be secured to a rigid supporting structure, a tubular guide of circular cross-section afiixed to said brackets, said guide having a central axis of rotation, a portion of one surface of said guide beingremoved to form a continuous'opening extending longitudinally along the length of the guide; said opening including at least about 45 of the periphery of said circular cross-section, a pair of G-shaped plates each having a web and a lower leg positioned within said guide, a portion of the web of each C-shaped plate extending outwardly from the guide through said opening, the outermost end of said webs being affixed relative to each other; the lowerleg of each plate extending in opposed directions to each other, an intermediate plate afi'ixed to the outwardly extending web on each plate and being spaced from and parallel to said lower leg, a plurality of bearings mounted on axes extending between said lower leg and said intermediate plate on each individual C-shaped plate, said axes being rotatably mounted parallel to each other, said bearings being barrel-shaped to conform to and engage the inner surfaces of the guide such that the C-shaped plates may move longitudinally along the guide and pivot transversely relative to the guide.

References Cited in the file of this patent UNITED STATES PATENTS Carscallen Nov. 18, 1947

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