US2424840A - Drafting apparatus - Google Patents

Description

i July29, 1947. w. H. MURPHY .27,424,840

DRAFTING APPARATUS Filed April 1o, 1944l 2 sheets-sheet 1 July .29, 1947# I w. H. MURPHY DRAFTING APPARATUS Filed April 1o, 1944 2 Sheets-Sheet 2 Patented July 29, 1947 UNITED STATES PATENT OFFICE DRAFTING APPARATUS William H. Murphy, Chicago, Ill.

Application April 10, 1944, Serial No. 530,243

6 Claims.

My invention relates generally to drafting apparatus and more particularly to improved apparatus of this character having a universally adjustable head mounted for transverse movement on a mobile straightedge.

It is an object of my invention to provide an improved drafting apparatus which may be easily adjusted to facilitate drawing lines at any desired angle and at any position upon the drafting board or table.

A further object is to provide an improved drafting apparatus which is very simple in construction and may be produced at a much lower cost than comparable apparatus made in the past,

Other objects will appear from the following description, reference being had to the accompanying drawings, in which Fig. 1 is a plan view of a drawing board with the improved apparatus of my invention installed thereon;

Fig. 2 is an enlarged plan view of a slightly modified form of the invention, in that the protractor head is provided with but a single arm;

Fig. 3 is a rear plan view of a portion of the apparatus shown in Fig. 2;

Figs. 4 and 5 are enlarged sectional views taken on the lines 4--4 and 5 5, respectively, of Fig. 2;

Fig. 6 is a fragementary sectional view taken on the line 6-6 of Fig. 4 and showing the head clamping means in clamping position; and

Fig. 7 is a view Similar to Fig. 6, showing the parts of the clamping mechanism in released position.

Referring to Fig. 1, the apparatus of my invention is illustrated as being mounted upon a drafting board, or table, III, which may be of any suitable construction, and which is equipped with a mobile straightedge I2. This straightedge is preferably of the general construction shown in the patent to H. L. De Lisle, No. 2,256,241, As shown in greater detail in said patent, the mobile straightedge I2 is constrained for translatory movement by means of cables I4 and I6, the ends of which are joined by a spring slack take-up device I8, and the opposite ends of which are respectively anchored to the board or table I at the lower edge thereof. The cable I6 passes around a pulley which includes a suitable cable clamp 22 normally engaged with the cable to prevent movement of the cable I6 around the pulley 20.

When it is desired to have the straightedge I2 positioned at an angle to the horizontal edge of the board IU, the clamp 22 may be released and 2 the straightedge I2 then adjusted tothe desired angle, whereupon the clamp 22 is reengaged. Thereafter, the straightedge I2 will be translatable upwardly and downwardly on the board Ill, but will maintain the set angularity with respect to the horizontal edge of the board.

As best shown in Figs. 4 and 5, the straightedge I2 comprises a strip 24 of a suitable nonwarping plastic material, such as Formica XX, with a raised shoulder portion 24a which is shown as formed of a separate strip of material cemented thereto and upon which a complementary strip 26 is secured by a plurality of drive screws 28, The edges of the strip 24 are grooved for the reception of transparent plastic ruler edges 30, 3l, which may be secured in place by a suitable adhesive. The contacting faces of the strips 24a and 26 are provided with opposed grooves forming a passageway 34 for the operating cables I4 and I 6.

The longitudinal edges of the strip 26 are undercut to provide way or guide surfaces for complementally beveled washers 36 secured to a protractor body 38 by screws 40, and for engagement by a clamping bar 42 having a beveled edge 44. A strip or shoulder 24a is reversely and complementarily beveled on its longitudinal edges with respect to the undercut edges of strip 26, and in the form illustrated is extended laterally slightly beyond the meeting edges of strip 26. The clamping bar 42 is mounted for lateral sliding movement with respect to the protractor body 38 by means of a pair of rivets 46 which are laterally slidable in slots 48. As best shown in Figs. 6 and 7, the bar 42 is pressed against the beveled edge of the strip 26 by a bowed wire spring '50, the ends of which fit in suitable sockets 52 formed in the bar 42, and the central portion of which reacts against a screw 54.

The bar 42 is adapted to be moved laterally to cause its beveled edge 44 to be disengaged from the adjacent under-cut edge of the strip 26 suicently to permit removal of the protractor head 38 from the straightedge. The means for accom.- plishing such movement of the :bar 42 comprises a manually operable lever 56 secured to a crankshaft 58 mounted for pivotal movement in the head 38; The crank portion of the shaft 58 projects into a longitudinal slot 60 formed in the bar 42 so that upon rotation of the lever -56 from its normal horizontal position (Fig. 2) to a substantially vertical position (Fig. '7), the bar 42 is moved laterally against the resilient force of the spring 50 a su'icient distance to free the edge 44 of the clamping bar 42 from the adjacent under- 3 cut beveled edge of the strip 2B of the straightedge. When the clamping bar 42 is moved to this position, as shown in Fig. 7, the protractor head may be removed from the straightedge.

The body 33 of the protractor head is drilled to receive a headed socket member E2 which is internally threaded to receive a stud 64 which may be molded as an insert in a knob 6B. The movable part 68 of the protractor is pivoted on the socket 62. and is frctionally clamped to the body 38v by an undercut Washer 1G. The protractor part 68 ts closely in a complemental recess 12 formed in the upper surface of the body 38, and the upper surface of the protractor part 68 has angular degree graduations 14 marked thereon in a suitable manner, these. graduations cooperating with Vernier graduations 1.6 marked on the upper surface of the body 38 adjacent the graduations 14.

The protractor part 68 may be provided with a single arm 18 as shown in Figs. 2 and 3, or may have a. pair of mutually perpendicular arms 8l).

'In each instance, the arms 18 and 80 are provided with suitable dovetail slots for the reception of complementary parts on ruler arms 82, so that the latter may be detached whenever desired.

From a consideration of the fact that the mobile straightedge 2 may be adjusted for translatory movement while at any desired inclination to the horizontal, it. will be clear that the apparatus may be used with great convenience in the making of drawings having a non-horizontal base line. In making such drawings, the mobile straightedge l2 is adjusted to lie parallel to the base line andl the apparatus may then be used to. draw lines. at predetermined angles with respect to. the base line, by setting the protractor part 6a at such angle with respect to the O mark of the Vernier graduations 16. The making of drawings of this type is thus facilitated as compared with making` them with a conventional drafting machine, in. that all angular dimensions may be read direct-1y from the graduations. 14, whereas in the conventional drafting machine. such angular dimensionswould have to bev computed from the scale reading` of the machine by adding or subtracting the anglev by which the base line deviates from the horizontal.

'The spring 50., through the bar 42, secures the body 38- of the protractor head iirmly to the straightedge so that it will not tilt relative thereto, and applies sufficient clamping force to produce friction between the bar 42 and the strip 26. so that. the head will not be liable to accidental displacement from the position on the straightedgeY I 2v to which it is set. Whenever the protractor head is not to be used it may readily be disengaged from the straightedge I2 merely by swinging the wing lever 55 to a vertical position, whereupon the bar 42 will be moved out of the` undercut bevel of the straightedge sufficiently to perm-.it the protractor head to be raised and removed fromv the straightedge l2. Similarly, the head. may be easily and quickly attached to the straightedge.

While 'I' have shown and described particular embodiments of myv invention, it will be apparent that numerous variations and modifications thereof` may be made without departing from the underlying principles of the invention. I therefore desire, by the following claims, to include within the scope4 of my invention, all such variationsA and modications by which substantially the results ot my invention may be obtained 4 through the use of substantially the same or equivalent means.

I claim: 1. In combination, a straight-edge having under-cut longitudinal edges, a protractor member slidably mountedY on said straight-edge and having retaining members engaging beneath one of said under-cut edgesl and an engaging member slidably mounted upon said protractor head and provided with means movable into and out of position engaging beneath the other of said under-cut edges.

2. In combination, a straight-edge having under-cut longitudinal edges, a protractor member slidably mounted on said straight-edge, and having retaining members engaging beneath one of said under-cut edges, an engaging member slidably mounted upon said protractor head and provided with means movable into and out of position engaging beneath the other of said under-cut edges, and spring means coacting with said last named member to urge the same into engaging position.

3.. In combination, a straight-edge having under-cut longitudinal edges, a protractor member slidably mounted on said straight-edge, and having retaining members engaging beneath one of said under-cut edges, an engaging member` slidably mounted upon said protractor head and provided ivith means movable into and out of position engaging beneath the other of said undercut edges, spring means coacting with said last named member to urge the same into engaging position, and means manually operable to retract-l said last named member against the action of said spring to permit disengagement of said. protractor from said straight-edge,

4. A straight-edge, a protractor slidably mounted thereon, said straight edge being provided with under-cut longitudinal edges, said pro.- tractor being provided with retaining members engageable beneath one of said under-cut edges, said protractor member additionally beingA provided with slots, securing members slidably 45 mounted in said slots and headed at one end to prevent disengagement from said protractor member, an engaging member carried by said securing members at their opposite ends and movable into and out of position engaging beneath 50 the other of said under-cut edges, and means yieldingly urging said securing member in engaging position.

5. A straight-edge, a protractor slidably mounted thereon, said straight-edge being pro- 55 vided with' under-cut longitudinal edges, said protractor being provided with retaining members engageable beneath one of said under-cut edges, said protractor member additionally being provided with slots, securing members slidably 60 mounted in said slots and headed at-onev end to prevent disengagement from said protractor member, an engaging member carried by saidjsecuring members at their opposite ends and movable into and out of position engaging beneath 65 the other of said, under-cut edges, means yieldingly urging said securing member in engagingl position, said last named. means comprising a, spring member and a pin` coacting therewith and carried by said protractor member.

6. A straight edge, a protractor slidably mounted thereon, said straight edge being provided with undercut longitudinal edges, said protractor being provided with retaining members engageable beneath one of saidunder-cut edges.. 75 said protractor member additionally being provided with' slots, securing members slidably mounted in said slots and headed at one end to prevent disengagement from said protractor member, an engaging member carried by said securing members at their opposite ends and movable into and out of position engaging beneath the other of said under-cut edges, means yieldingly urging said securing member in engaging position, and means to disengage said engaging member comprising a manually operable eccentric member carried by said protractor member and engaging said engaging member.

WILLIAM H. MURPHY.

REFERENCES CITED The following references are of record in the file of this patent:

Number Number UNITED STATES PATENTS v Name Date Graves Apr. 7, 1942 Linsner Sept. 18, 1923 De Lisle Sept. 16, 1941 Fatkin Oct. 26, 1943 Christian May 25, 1926 FOREIGN PATENTS Country Date French Oct. 23, 1925 Great Britain A. D. 1943 Germany Dec. 28, 1926

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