US2242827A - Drafting device - Google Patents

Description

May 20, 194h A.`LANGSNER 2,242,827

DRAFTING DEVICE Filed Nov. 6, 19:69

I N VENTOR.

ATTORNEY.

Patented May 20, 1941 DltAFT-ING DEVICE Adolph Langelier, Chicago, Ill., assigner to Eugene Dietzgen Co., Chicago, Ill., a corporation of Delaware .Application November 6, i939, Serial No. 302,943

l Claim.

My invention relates in general to drafting equipment and has more particular reference to line drawing guides, the invention more especially relating to a demountable straight edge structure particularly adapted for use in connection with parallel motion apparatus of the sort shown in my co-pending application, Serial No, 179,832, filed December l5, 1937, for Drafting apparatus.

An important object of the present invention is to provide light weight ruling guides or straight edges, having improved means for removably mounting the same in accurately aligned position in a guide Acarrier or support.

Another important object is to provide adjustable means on a ruling guide for securing the same on a guide mount, while permitting the relative position of the guide with respect to the mount to be adjusted without dismounting the guide.

Another important object resides in grooving or otherwise relieving the under surface of the guide in order not only to reduce the weight thereof, but to reduce the surface area of the guide in contact with the working surface, so as to reduce the danger of smearing the work in moving the guide upon the work surface.

Another important object is to form the guide, on its under side, with a plurality of grooves, whereby to lighten the same and reduce the surface area thereof in contact with the working surface, a pair of grooves defining a land therebetween to provide for the reception of fastening members, the land being disposed entirely behind the working surface so that the same is contacted only by the edge portions of the guide when the same is placed and moved on the working surface.

Another important object is to coat the work surface engaging portions of the guide with lacquer or other protective coating to prevent the material of the guide, when made of aluminum or other smearable metal, from soiling the working surface when moved thereon.

Another important object is to provide adjustable means for mounting a guide of the character mentioned in a support; a further object being to provide a plate tiltably mounted on the.

guide, and means for clamping the plate in adjusted position on the guide, the opposed edges of the plate being beveled and tapered for removable wedging association in a correspondingly beveled guide support.

These and numerous other important objects, advantages-and `inherent functions of the invention will become apparent as the same is more fully understood from the foregoing description, which, taken in connection with the accompanying drawing, discloses a preferred embodiment of the invention.

Referring to the drawing,

Figure 1 is a View of drafting apparatus, namely, a parallel motion device fitted with line drawing guides or rulers embodying, and as taught by, my present invention;

Figure 2 is a plan view showing the under side of a guide support forming a part of the parallel motion device shown in Figure 1;

Figure 3 is a sectional view taken substantially along the lines 3 3 in Figure 2;

Figure 4 is an enlarged plan View of a portion of a ruling guide embodying my present invention and showing an adjustable mounting device for securing the guide on the support illustrated in Figures 2 and 3;

Figures 5 and 6 are sectional views taken, respectively, along the lilies 5 5 and 6-6 in Figure Li; and

Figure 7 is a sectional view taken substantially along the line l-'I in Figure 1.

To illustrate my invention, I have shown on the drawing a drafting apparatus comprising parallel motion mechanism II, including a mounting I3 for supporting line drawing guides I5 on the mechanism, although, of course, the invention is not necessarily restricted to parallel motion mechanism, but has application generally to line drawing guides and the mounting thereof on any suitable guide support.

The parallel motion mechanism comprises a pair of arm elements I'I and I8 relatively pivoted as at Ill, the arm II being provided for pivotal attachment, as at 2|, on a table or board forming the drafting or working surface, Athe guide mount I3 being carried on and by the lfree end of the arm I8. The arms I1 and I 8 are formed and arranged in any conventional or preferred manner to carry the support I3 in a predetermined, relative angular relationship with respect to the Working surface, while permitting the same to be moved universally throughout the working surface and within the range of arm movement of the mechanism.

In drafting apparatus of the character mentioned, it is usual to provide a pair of straight edge rulers or ruling guides extending at right angles the one with respect to the other, and so I have shown a pair of ruling guides I5 so mounted on the guide mount I3.

Each of the ruling guides I5 comprises .an

elongated strip of material, having Opposed lateral edges 23 accurately formed in parallelism and beveled, as at 25, to form straight ruling edges along the opposite sides of each guide I5, the medial portions of the guide between the beveled portions 25 being formed preferably to provide a substantially flat, upwardly facing surface 21. The guides I5, of course, may be made of any suitable material, but I prefer to form the same of a light weight metal, such as aluminum, or an aluminum alloy, for the sake of lightness, since weight is a factor in apparatus designed for continuous all day use, as by a busy draftsman. Excessive weight, particularly in large scale equipment, results in appreciable fatigue when used continuously and rapidly, and consequently I prefer to employ the lightest possible material having adequate strength and rigidity to enable the guide to retain its shape and accuracy throughout its service life and under misuse and abuse to which it may be subjected. I nd that aluminum and aluminum alloys are admirably suited for the purpose, although wooden guides also may be utilized.

In order to provide a guide having minimum weight, without sacrificing requisite strength, I prefer to relieve the under side of the strip comprising the guide by removing the material of the strip preferablyv longitudinally of the guide between the Opposed ruling edges 23 thereof.

' Material may thus be removed by longitudinally grooving the under side of the strip, and I prefer to form a pair of parallel grooves 29, defining therebetween a longitudinal rib 3i extending preferably throughout the length of the guide, although this rib 3| may be cut away at intervals to further reduce the weight of the guide. The grooves 23 are formed inwardly of the 0pposed ruling edges 23 to form lands 33 in the under side of the guide adjacent the ruling edges 23. These lands 33 form bearing surfaces in position to engage the drafting or working surface to which the guide or ruler may be `applied for drafting purposes, and it will be noted that the rib 3| terminates slightly behind the plane which includes the bearing surfaces 33, so that when the guide is applied to a working surface, the rib 3| is maintained out of contact with such surface. This is of advantage particularly where the guide is formed of aluminum or other metal. Metals, when rubbed on a drafting surface such as paper, have a tendency to smear the surface, and by relieving the under side of the guide, smearing is reduced to` an absolute minimum.

The rib 3| serves multiple purposes. It not only affords a thickened guide section for receiving and adequately supporting fasteners 35 for attaching auxiliary means on the guide, but also provides longitudinal reinforcement for rigidifying the guide, and, further, since its lower surface is but slightly offset from the plane passing through the bearing surfaces 33, it affords additional support for the ruler in the event that the same is subjected to excessive pressure downwardly upon the work surface. If the ruler is accidentally or otherwise subjected to excessive pressure applied on the upper surface 21 thereof, the bottom of the rib 3| will limit the ruler flattening effect of such excessive pressure upon engagement with the work surface, the normal clearance provided between the rib and the working surface being such as to limit the ruler flattening effect well within the elastic limits of the ruler material, so that even though the guide section in the lateral portions of the ruler be made exceedingly thin to lighten the device to a maximum degree, yet the presence of the longitudinal rib 3| will effectively prevent damage and distortion of the ruling guide.

The guide mount I3 comprises a preferably thin strip or plate, preferably of metal, formed, as at 31, for attachment in any desired relative angular position on the free end of the arm I8. In the illustrated embodiment, the support member I3 comprises a pair of ruler mounting portions 39 preferably extending relatively at right angles, the one with respect to the other. At the base of each of the mounting portions 39, the under side of the mount I3 is provided with a shallow circular cavity 4I, and the portions 33 are each provided with an elongated groove or channel 43, extending laterally fromvand communicating with the cavity at one end, the channel 43 opening at its other end at the terminal ends of the portions 39. The side edges of the grooves 43 are beveled, as at 45, and converge slightly from` the terminal ends of the portions 39 to the cavities 4I.

The guides I5 are each provided, preferably at'both ends thereof, with mounting means 41, comprising preferably metallic strips pivoted at one end, preferably by means of a flat headed screw 49, at adjacent the end of the guide I5. The strips 41 are cut away laterally, as at 5I, to provide edge portions 53 and 55 on opposite sides of the strip 41, which edge portions are beveled, as clearly indicated at 56, and arranged to converge toward the pivoted end of the member 41, whereby said edges 53 and 55 may wedgingly enter the channels 43 and be wedgingly received therein, whereby to demountably assemble the guides on the mounting portions 39.

In order to permit accurate angulation of the guides I5 on the mount I3, I provide for fastening the end of the strip 41, opposite from the -pivoted end thereof, on the guide in adjustable fashion. To this end, the strip 41 is provided with va curved slot 51 in its end remote from the pivot screw 43, said slot having curvature centering on the pivot 49; and I provide a clamping screw 59, extending in the slot 51, for the purpose of securing the member 41 at an adjusted angulation on the guide. It will be noted that both the pivot screw 49 and the clamping screw 59 comprise the fasteners 35 heretofore mentioned, which are received in threaded openings formed in the rib 3|.

After a guide has been assembled on the mount I3 by wedging the strip 41 in the channel 43, the flattened head of the pivot screw 49 permitting the strip to be forced into place in the channel 43, the clamping screw 59 may be loosened and the guide accurately angulated on the mount I3, after which it may be clamped in adjusted position by tightening the screw 59 to hold the parts in adjusted position. In this connection, it will be noted that-the beveled edges 53 and 55 of the strip 41 are arranged so that when wedgingly received in the channel 43, the clamping screw 59 is exposed downwardly of the end of the mounting portion 39 to permit manipulation thereof after the ruler has been assembled on the mount 'I'he guides I5 may be formed with any usual or preferred scale graduations on the inclined surfaces 25r thereof adjacent the ruling edges 23, the graduations preferably being formed by engraving or otherwise marking the same in the material of the ruler. I prefer also, particularly where the ruler comprises a metal, to coat the same, and

particularly the surfaces of the lands 33, with a lacquer or enamel baked thereon. 'This coating may, of course, cover the ruler entirely for the purpose of protecting the same from corrosion and for improving the appearance of the ruler, but the presence of a baked coating on the lands 33 Where the ruler comprises a metallic material will serve absolutely to prevent smearing of the Work surface by preventing direct metallic contact therewith at the lands 33.

It is thought that the invention and numerous of its attendant advantages will be understood from the foregoing description, and it is obvious that numerous changes may be made in the form, construction and arrangement of the several parts Without departing from the spirit or scope of the invention, or sacricing any of its attendant advantages, the form herein described being a preferred embodiment for the purpose of illustrating the invention.

The invention is hereby claimed as follows:

A ruling guide comprising an elongated mem ber defining a pair of spaced ruling edges, means formed on the underside of said member to provide spaced edge lands forming bearing surfaces adjacent said ruling edges, and an additional land forming a bearing surface intermediate said edge lands and offset with respect to the plane of said edge lands to normally afford a slight clearance between the bearing surface of said additional land and a working surface on which used whereby to allow contact of the guide with the working surface only at the bearing surfaces of said edge lands, said ruling guide having portions

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