US3892041A

US3892041A - Drafting board straight edge assembly

Info

Publication number: US3892041A
Application number: US449958A
Authority: US
Inventors: William A Adair; Richard F Pollowy
Original assignee: Teledyne Inc
Current assignee: Teledyne Inc
Priority date: 1974-03-11
Filing date: 1974-03-11
Publication date: 1975-07-01
Anticipated expiration: 1992-07-01
Also published as: CA1033160A

Abstract

A straight edge assembly, for cord mounting on a drafting board utilizing pulley block units located at the ends of the assembly for stringing the cord thereon. The pulley block units at each end of the straight edge assembly are releasably engaged therewith and may be conveniently dismantled for cord restringing without using tools.

Description

United States Patent Adair et al. July 1, 1975 [54] DRAFTING BOARD STRAIGHT EDGE 2,275.25] 3/1942 De Lisie 33/80 ASSEMBLY FOREIGN PATENTS OR APPLICATIONS (75] Inventors: William A. Adair, Des Plain s; 1,303.49! 8/]962 France 33/30 Richard F. Pollowy, Schaumburg, 604.0[0 6/1948 United Kingdom 33/80 both of III. 661MB) 4/1965 Belgium 33/80 [73] Assigneez Teledyne, Inc., Los Angeles, Calif. Primary Examiner Harry N. Hamian [22] Filed: Mar. ll, 1974 21 Appl. No.: 449,958 ABSTRACT A straight edge assembly, for cord mounting on a s 21 US. Cl. 33/80 drafiing ward utilizing Pulley block "nits located at 5| Int. Cl B43] :3/02 the ends of the assembly for Stringing the cord [58] Field of Search 33/80, 81 thereon The Pulley block units at each end of the straight edge assembly are releasably engaged there- [56] References Cited with and may be conveniently dismantled for cord re- UNITED STATES PATENTS stringing without using tools.

l,658.683 2/1928 Jacob 33/80 3 Claims, 9 Drawing Figures DRAFTING BOARD STRAIGHT EDGE ASSEMBLY BACKGROUND OF THE INVENTION This invention relates to a drafting board straight edge assembly. and particularly to innovations and improvements in a straight edge assembly for cord mounting to a drafting board. More specifically. the invention relates to novel pulley block units located at the ends of said straight edge assembly through which the mounting cord runs and which can be dismantled and removed from said straight edge for cord re-stringing purposes without the use of tools.

Heretofore. straight edges in general use which have been cord mounted to a drafting board by pulley means located at each end of the assembly have not been dismantleable without use of tools. The usual method has been to use screws to join pieces making up the straight edge assembly. Also. end covers. or caps usually adjacent the pulley means. have been attached to the straight edge by use of screws.

The pulley means attached to said end covers usually are located either inside a channel running lengthwise through said straight edge or on the side of the drafting board opposite that on which the straight edge is located and immediately therebeneath. In either case. pulley means are located in as small a space as practically possible and as close to the straight edge or drafting board as attainable so that the mechanism is not pulled. jerked. banged or torn. from the drafting board because it may be protruding therefrom. In either case. access to pulley wheels or sheaves is difficult because of space limitations. Therefore. dismantling the straight edge in order to replace a worn mounting cord, replace portions of the straight edge. recover the drafting board. or other purposes has required the use of tools. most likely at least a screw driver, to gain access to the pulley means to sheaves.

The present invention allows disassembly of the straight edge without using tools, by joining portions of the straight edge permanently with double faced adhesive tape and utilizing end covers or caps including pulley means. The caps are frictionally retained but slidably disengageable from the straight edge body by gripping said pulley block unit and pulling laterally away from the straight edge body. Reassembly of the straight edge is readily accomplished.

It is therefore an object of this invention to provide a straight edge assembly which may be conveniently assembled and disassembled manually without use of tools.

Another object of the invention is in the provision of a pulley block unit located at each end and partly inside a straight edge which is cord mounted to a drafting board and is manually releasably engageable with said straight edge.

Other objects. features and advantages of the invention will be apparent from the following detailed disclosure taken in conjunction with the accompanying drawings. wherein like reference numerals refer to like parts. in which:

FIG. 1 is a perspective of a drafting board having a straight edge assembly cord mounted thereto with the straight edge body partially broken away to show a pulley block unit located at the end of the straight edge;

FIG. 2 is a stringing diagram of the cord by which the straight edge assembly of FIG. 1 is mounted upon the drafting board;

HO. 3 is an enlarged plan view of one end of the straight edge assembly of FIG. 1 inverted with a pulley block unit shown partially withdrawn from the straight edge channel in which the unit is slidably mounted;

FIG. 4 is a cross section taken along line 44 of FIG. 3 showing the channel located inside the straight edge;

FIG. 5 is a top plan view of one of the pulley block units of the straight edge assembly shown in FIG. 1;

FIG. 6 is a bottom plan view of one of the pulley block units.

FIG. 7 is a side elevational view partially in vertical of one of the sheaves in the pulley block units;

FIG. 8 is an end view of one of the pulley block units; and

FIG. 9 is a side view of one of the pulley block units.

Referring now to the drawings and particularly to FIG. 1, a drafting board is shown having a straight edge assembly 11 mounted thereon by means of cord 12 which is fastened to the drafting board 10 at clamp 13. guided by clips l4-14a and pinched and restrained by retainers 15-15a. Straight edge assembly 11 includes a body 18 which is permanently assembled having an edge portion 19 made of transparent material, a grasping portion 20, and pulley block units 2l21a located at opposite ends of said body 18.

in FIG. 2 the cord stringing diagram shows the conventional relationship of cord 12 to the drafting board 10 and the straight edge assembly 11. Cord 12, shown with arrows added thereto for diagraming purposes only, is strung as follows. First, the cord is clamped medially in clamp 13 and each side is positioned around a guide clip 14-1412 and along a side of drafting board 10. Then each cord end passes into straight edge assembly 11 at pulley unit blocks 2l-21a and around sheave 2424a. Midway through the assembly the cords cross over one another and each end passes around a second pulley 2626a and down an opposite side of drafting board 10 where it is restrained in pinching retainer 15-1501.

Referring to FIG. 3 wherein an end portion of straight edge body 18 is shown turned upside down. one end of the cord 12 enters pulley block unit 21 at end cap portion 30 through an end cap passageway 31. passes over pulley 24 mounted in the sheave mounting portion 32 and outof the pulley block unit into the body 18 through recess 33 also located in sheave mounting portion 32. The other end of cord 12 follows a reverse path. in through recess 33, around sheave 26a, and out passageway 31a.

As is conventional, the cord mounting of said straight edge assembly is such that cord length remains taut and constant when the straight edge assembly 11 is moved vertically on drafting board 10. The cross over stringing relationship insures the biasing of straight edge assembly 11 at the same reference angle to drafting board 10 wherever said assembly 11 is moved up or down on said drafting board 10.

FIG. 4 shows the spatial relationship between edge portion 19, grasping portion 20, the mounting therebetween. and the C-channel 36 into which the sheave mounting portion 32 of the pulley block units 21-210 are placed. Edge portion 19 is a rectangular strip of transparent material such as acrylic plastic. Grasping portion 20 is a modified C-channel which may be made of extruded aluminum, steel, plastic or wood. The inturned free ends 37, 38 of grasping portion 20 are mounted permanently to edge portion 19 by means of strips of double faced adhesive tape 39-39 made of a compressible sponge-like material having adhesives on both sides thereof. The different coefficients of expansion of grasping portion 20 and edge portion 19 are compensated for by the flexibility of double faced edged adhesive tape 39-39. Also shown in FIG 4 is a dry lubricant tape 40 applied on the bottom of edge portion 19. The bottom exposed surface of dry lubricant tape 40 has a low coefficient of friction and cases movement of straight edge assembly 11 across the top of drafting board 10. Also, the slight thickness of dry lubricant tape 40 raises edge portion 19 from the drafting board slightly reducing the possibility of capillary action smudges on drawing medium mounted on the board as an ink line is being drawn along the edge of straight edge portion 19. FIG, 4 shows the cross section shape of channel 36. lt is this channel into which sheave mounting portions 32 of pulley block units 21-210 fit and are frictionally retained so as to be slidably removable therefrom. The outer shape and dimensions of grasping portion 20 are approximately the same as the shape and outer dimensions of end cap por tion 30.

The details of construction of the pulley block units 2l-2l0 will now be described in connection with FIGS. -9. Referring to FIG. 5 the outside surface 43 of end cap portion 30 is preferably of a rough or nonsmooth texture providing gripping means facilitating removal of pulley block unit 21-210 from straight edge body 18. As shown, sheave mounting portion 32 has a generally planar top surface 44 and generally planar side surfaces 45-45 except for nubs or detents 46 which protrude from side surfaces 45-45. Top surface 44, side planar surfaces 45-45. and bottom surfaces 47-47 have outside dimensions slightly smaller than the corresponding interior dimensions of grasping portion channel 36. In this embodiment, nubs or detents 46 are provided to give a proper sliding fit for sheave mounting portion 32 in grasping portion C-channel 36. Sheave mounting portion 32 slides into the C-channel until end cap portion shoulder 50 engages the inner shoulder of grasping portion 20. Inner shoulder 51 is indented from the end of assembly 11 approximately the thickness of end cap portion 30. End cap portion 30 then fits in the indented portion when pulley block unit 21-210 is in place. In FIG, 8 the C-shape ofend cap portion shoulder 50 is shown.

Turning now to FIG. 6, end cap portion passageways 31-310 and sheave mounting portion recess 33 are shown along with

sheaves

24 and 26a. Cord 12 moves in and out of pulley block unit 21 through said passageways 31-310 and said recess 33. Sheaves 24, 24a, 26 and 260 are identical and are shown in enlarged partially sectioned form in FIGv 7. The sheave is a circular disk having a spindle mounting 52 through the center of said sheave from one side to the other and a groove 53 running along the center of the circumference of said sheave. The sheave also has an integrally formed spacer hub 54 which prevents movement of the sheave axially on spindle 55-550 located in sheave mounting portion 32. It should be noted that there is no retainer other than the bottom side wall 57 of channel 36 which retains

sheaves

24, 240, 26, and 260 on the spindles 55-550. Also shown in FIG. 6 is cord guide 58 which is located in both sheave mounting portion 32 and end cap portion 30. Cord guide 58 is curved immediately adjacent each sheave outer circumferential surface in the area where cord 12 is located in groove 53. Wall 58 prevents cord 12 from leaving groove 53 by covering the top of the groove 53.

In operation, each end of cord 12 is placed at an opposite end of channel 36, moved through channel 36. and out the opposite end thereof One method of performing this function is to place a small weight on each end of cord 12 while holding straight edge body 18 vertically and dropping the weighted end into and through channel 36. Body 18 is then inverted and the operation repeated using the other end of cord 12. With one portion of cord 12 going in and another portion of cord 12 coming out each end of body 18, those two portions are placed in

sheaves

24, 26 and 240, 260, respectively, and the sheaves placed on their respective spindles 55 and 550. Pulley block units 21-210 are then slidably moved into installed position with sheave mounting portion 32 inside C-channel 36. Thereafter, the two loose cord ends are placed through and retained by pinching retainers 15-150 at the bottom side edges of board 10.

It should be noted that cross over cord mounting causes inward cord pressure on

pulleys

24, 240, 26, 260 toward the center of straight edge assembly 11. This causes pulley block units 21-210 to be maintained in place with sheave mounting portion 32 inside C- channel 36 and prevents said units 21-210 from wandering out of installed position.

In this embodiment, pulley block units 21-210 and sheaves 24-240, 26-260. are made of molded plastic. It can be appreciated that other suitable materials may be utilized without detracting from the scope of the invention. It can also be appreciated that while, in this embodiment, the open end of spindles 55-550, face downward and sheaves 24-240, 26-260 are mounted from the bottom that the mounting could be reversed, i.e., mounting from the top, without detracting from the scope of the invention. Also, it is possible that sheaves 24 and and 260 or 240 and 26 could be placed vertically on one spindle S5 and perform the same function as in the disclosed invention.

We claim:

1. in a straight edge assembly for cord mounting on a drafting board the improvement comprising a permanently assembled body including an edge providing portion and a grasping portion, and a pulley block unit located at each end of said assembly which is manually removable and replaceable without the use of tools, each said pulley block unit including an integrally formed pulley block and at least one sheave mounted therein, said block having an end cap portion for covering at least a part of the end of said body, a sheave mounting portion adjacent said end cap portion including a spindle on which said sheave is mounted and retained in place by said contiguous body part, a recess through which said mounting cord passes. and means for frictionally retaining each said pulley block unit to a contiguous body part at the end of said assembly and allowing releasable sliding engagement therebetween including a nub extending from an outside surface of said portion which frictionally engages said contiguous body part.

2. The improvement of claim 1 wherein said end cap portion further comprises, gripping means thereon to facilitate removal thereof from said body portion. a shoulder at the juncture of said end cap and said sheave mounting portions. said shoulder having the outer di mensions of said body adjacent thereto and inner dimensions of said sheave mounting portion and said end cap portion having at least one passageway therein for traversal of a mounting cord therethrough 3. In a straight edge assembly for mounting on a drafting board by a cord fastened mediate its ends to said board. said assembly including a body having an edge portion and a downwardly-facing C-channel shaped grasping portion the free ends of which channel are permanently attached to said edge portion. the improvement comprising. an integrally formed pulley block unit located at and partly inside each end of said body which is manually removable and replaceable without the use of tools. each said pulley block unit including an end cap portion. a sheave mounting portion attached thereto. and a pair of sheaves mounted side by side therein. said end cap portion having outside dimensions corresponding approximately to the cross sectional outside dimensions of said grasping portion, gripping means for facilitating lateral manual removal of said unit from said assembly. a pair of passageways therein for the traversal of said cord therethrough. and a shoulder at the juncture of said marginal portion and said sheave mounting portion having the outside dimensions of said body adjacent thereto and the inside dimensions of said sheave mounting portion. said shoulder limiting the travel of said pulley block unit in said body channel. said sheave mounting portion having outside cross sectional dimensions not appreciably greater than the corresponding inside dimensions of said channel in said body and frictionally retained therein. a pair of spindles each having a sheave rotatably mounted thereon. said spindles being retained in place by said contiguous body part. a cord retaining shoulder on said mounting portion around said sheave preventing said cord from disengaging a groove in said sheave. a recess from said sheave to an inside end sur face of said mounting portion through which said cord is free to move. a nub protruding slightly from a surface of said portion adjacent an interior surface of said body making contact with said surface which prevents said pulley block unit from sliding out of said channel unless pulled therefrom, and a pair of sheaves each rotatably mounted on one of said spindles and having a protruding hub on at least one side of said sheave preventing the movement of said sheave axially along said spindle.

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3,892,041

DATED July 1, 1975 INVENTOR(S) Willaim A. Adair, and Richard F. Pollowy It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, Line 37 delete "to" and insert or in place thereof.

Signal and Scaled this twenty-eight Day of October 1975 [SEAL] A ttest:

C. MARSHALL DANN ('vmmissimrvr njlaremx and Trarlvmurks RUTH C. MASON Arresting Officer

Claims

1. In a straight edge assembly for cord mounting on a drafting board the improvement comprising a permanently assembled body including an edge providing portion and a grasping portion, and a pulley block unit located at each end of said assembly which is manually removable and replaceable without the use of tools, each said pulley block unit including an integrally formed pulley block and at least one sheave mounted therein, said block having an end cap portion for covering at least a part of the end of said body, a sheave mounting portion adjacent said end cap portion including a spindle on which said sheave is mounted and retained in place by said contiguous body part, a recess through which said mounting cord passes, and means for frictionally retaining each said pulley block unit to a contiguous body part at the end of said assembly and allowing releasable sliding engagement therebetween including a nub extending from an outside surface of said portion which frictionally engages said contiguous body part.

2. The improvement of claim 1 wherein said end cap portion further comprises, gripping means thereon to facilitate removal thereof from said body portion, a shoulder at the juncture of said end cap and said sheave mounting portions, said shoulder having the outer dimensions of said body adjacent thereto and inner dimensions of said sheave mounting portion and said end cap portion having at least one passageway therein for traversal of a mounting cord therethrough.

3. In a straight edge assembly for mounting on a drafting board by a cord fastened mediate its ends to said board, said assembly including a body having an edge portion and a downwardly-facing C-channel shaped grasping portion the free ends of which channel are permanently attached to said edge portion, the improvement comprising, an integrally formed pulley block unit located at and partly inside each end of said body which is manually removable and replaceable without the use of tools, each said pulley block unit including an end cap portion, a sheave mounting portion attached thereto, and a pair of sheaves mounted side by side therein, said end cap portion having outside dimensions corresponding approximately to the cross sectional outside dimensions of said grasping portion, gripping means for facilitating lateral manual removal of said unit from said assembly, a pair of passageways therein for the traversal of said cord therethrough, and a shoulder at the juncture of said marginal portion and said sheave mountiNg portion having the outside dimensions of said body adjacent thereto and the inside dimensions of said sheave mounting portion, said shoulder limiting the travel of said pulley block unit in said body channel, said sheave mounting portion having outside cross sectional dimensions not appreciably greater than the corresponding inside dimensions of said channel in said body and frictionally retained therein, a pair of spindles each having a sheave rotatably mounted thereon, said spindles being retained in place by said contiguous body part, a cord retaining shoulder on said mounting portion around said sheave preventing said cord from disengaging a groove in said sheave, a recess from said sheave to an inside end surface of said mounting portion through which said cord is free to move, a nub protruding slightly from a surface of said portion adjacent an interior surface of said body making contact with said surface which prevents said pulley block unit from sliding out of said channel unless pulled therefrom, and a pair of sheaves each rotatably mounted on one of said spindles and having a protruding hub on at least one side of said sheave preventing the movement of said sheave axially along said spindle.