US3537183A - Drawing board and t-square - Google Patents

Description

Nov. 3, 1970 R. J. ANDERSON 3,537,183

DRAWING BOARD AND T-SQUARE Filed Feb. 17, 1969 j yv vroe I k I Ray J. fl/voszso/v J w/W United States Patent 3,537,183 DRAWING BOARD AND T-SQUARE Roy J. Anderson, 1220 Crenshaw Blvd., Los Angeles, Calif. 90019 Filed Feb. 17, 1969, Ser. No. 799,778 Int. Cl. B431 13/02 U.S. CI. 33-76 1 Claim ABSTRACT OF THE DISCLOSURE A drawing board and T-square combination in which the drawing board has an upwardly facing channel extending along a side edge, the T-square having a head provided with lugs spaced laterally of the blade of the T- square and slidable in the channel for maintaining a right angular relation between the T-square blade and the channel. A locking device is carried by the T-square head, the locking device including a clamping plate having an end disposed in the channel in the board and a portion engaged by a pivoted cam, whereby the clamping plate is actuatable into engagement with one side of the channel to force the lugs on the T-square head into engagement with the other side of the channel.

Heretofore, drawing board and T-square combinations have been provided wherein the T-square head is adapted to be clamped or locked in a selected position of adjustment along an edge of the drawing board. Such prior combinations for the most have been relatively complex and, therefore, expensive to produce, on the one hand, or, on the other hand, the clamping devices have been such that the T-sqnare may not be positively and immovably held in a selected position upon operation of the clamping means.

In order to overcome the deficiencies of the prior art drawing board and T -square combinations and to provide a structure which is simple in its operation, yet positive in its locking action, the present invention provides a T- square and drawing board combination in which the drawing board is provided along one edge with an elongated channel having opposing, parallel side Walls between which lugs provided beneath the head of the T-square are snugly, yet freely, slidable, whereby to allow shifting of the T-square along the work surface of the drawing board, while holding the T-square blade in right angular relationship to the channel. The T-square head includes a clamp mechanism having a member engageable with one side wall of the channel and forcing the lugs carried by the T-square head into engagement with the other side wall of the channel, whereby the T-square head is positively and immovably held against angular movement by three-point engagement between the side walls of the channel on the board and the lugs and the clamping member on the T- square head.

In accomplishing the foregoing, the present invention provides a cam-operated locking mechanism involving a simple slidable plate having a first end flange engageable in the channel of the drawing board, and a second portion engageable by a pivoted cam member which locks the plate in position with the T-square immovably held in relation to the drawing board.

This invention possesses many other advantages, and has other purposes which may be made more clearly apparent from a consideration of a form in which it may be embodied. This form is shown in the drawings accompanying and forming part of the present specification. It will now be described in detail, for the purpose of illustrating the general principles of the invention; but it is to be understood that such detailed description is not to be taken in a limiting sense.

See

Referring to the drawings:

FIG. 1 is a view in perspective illustrating a drawing board and T-square made in accordance with the invention;

FIG. 2 is an enlarged top plan illustrating the T-square in locked condition with respect to the drawing board;

FIG. 3 is an enlarged fragmentary detail view in section, taken on the line 3-3 of FIG. 2;

FIG. 4 is a fragmentary top plan illustrating the T- square head in an unlocked condition; and

FIG. 5 is an enlarged fragmentary detail view in section, taken on the line 55 of FIG. 4.

As seen in the drawings, the invention contemplates a drawing board B, herein illustrated as a simple rectangular drawing board, but it will be understood that the board B may form part of a drafting table. For reference purposes, the board B will be seen to have an upper edge 1, a lower edge 2, a right-hand edge 3, and a left-hand edge 4. Extending longitudinally in parallel relation to the lefthand edge 4 of the board B is a channel 5. In the illustrative embodiment, the board B is shown as being the usual wooden drawing board in which the channel 5 is formed, and seated in the channel 5 is a metallic channel-shaped liner 6 having a left-hand side wall 7 and a right-hand side wall 8 disposed in parallel relation to one another and effectively defining the side walls of the channel 5. Preferably, the left-hand edge 4 of the drawing board B is a straight edge paralleling the channel-shaped member 6 so that, if desired, the usual T-square may be employed .and engaged with the edge 4 for performing work on a work sheet 9, which, as is customary, may be suitably secured to the work surface of the board B by thumbtacks 10, or, otherwise, as by adhesive tape or the like.

In accordance with the present invention, a T-square S is provided, this Tsquare including a head 11 and a blade 12 extending at right angles with respect to the head 11 and having a straight lwork edge 13. In the illustrative embodiment, the blade 12 and the head 11 are shown as being of unit construction, but it will be understood that, as is usual, the head may be attached to a separate blade. In any event, the head 11 has end portions 14 and '15 projecting laterally with respect to the blade 12, and, adjacent the outer extremity of these portions 14 and 15, they are respectively provided with downwardly extended lugs or projections 14a and 15a, each of which is shown as being in the form of a rectangular block depending from the T-square head and snugly but slidably engaged between the side walls 7 and 8 of the channel-shaped member 6. These lugs 14a and 15a serve to maintain the proper right angular relation between the channel-shaped member 6 and the blade 12 of the T square S, as the T-square assembly is moved upwardly and downwardly with respect to the work sheet 9 on the drawing board B.

However, when it is desired that substantial drawing work be done on the work sheet 9 using implements such as triangles in conjunction with the work edge 13- of the T-square blade 12, it is desirable that the "blade 12 be immovably held with respect to the drawing board B, to free both hands of a person for use. Thus, clamping or locking means L are provided for effectively clamping the T-square head 11 in fixed relation to the drawing board B, whereby the blade 12 is held in the desired fixed relation to the work sheet 9. This locking or clamping means L includes a clamp plate -16 having a horizontally extended body portion 17 slidably disposed in a groove 18 formed in and beneath the mid-section of the T-square head 11. A suitable fastener 19 is employed to secure the body portion 17 of the clamp plate 16 in the groove 18, this fastener extending upwardly through the plate 16 and through an elongated slot 20 in the T-square head 11, the fastener 19 having a head 21 of a greater dimension than defining with the body section 17 a channel-shaped portion 25 which receives a reduced thickness section 26 of the T-square head 11. Preferably, the end flange 22 of the clamp plate 16 is recessed within a depression 27 in the mid-section of the T-square head 11.

In order to eifect clamping movement of the clamp plate 16, a lever or cam 28 is provided, the lever being pivotally connected to a pivot pin or shoulder bolt 29 v which is threaded, as at 30, into the T-square head 11. The lever is provided with an operating handle 31 at one end, and, at the other end, the lever 28 has a downwardly extended cam pin 32 which extends downwardly into the recess 27 so as to be engageable with the inner edge 24a of the end flange 24 of the clamp plate 16. As seen in FIG. 2, the lever handle 31 may be rotated in a counterclock: wise direction so that the camming action of the lever pin 32 sliding along the edge 24a of the end flange 24 of the clamp plate 1 6 will force the clamp plate 16 to the left, thereby forcing the inner end flange 22 of the clamp plate 16 into frictional engagement with the outer side wall 7 of the channel-shaped member 6, resulting in the inner side walls 14b and 15b of the lugs 14a and 15a being forced oppositely into engagement with the inner side wall 8 of the channel-shaped member 6. Preferably, as seen in FIG. 2, the cam pin 32 moves to a position at which its axis is on a plane normal to the cam surface 24a and intersecting the axis of the pivot pin 29, whereby the plate 16 is locked in a clamping position by the lever 28.

Since the lugs 14a and 15a are laterally spaced with respect to the T-square blade 12, and since the clamp plate 16, and more particularly its flange 22, is centrally located with respect to the T-squarehead 11, the clamping action is such that the T-square head 11 will be immovably and positively held against movement with respect to the drawing board B. While spaced apart lugs have been illustrated and are preferred, it will be understood that the essential feature of the locking means of the invention is the opposite application of clamping face of the board B, to position the blade 12, and more particularly the work edge -13 thereof, in a desired and selected position with respect to the work sheet 9. Under these circumstances, the lever 28 will be in the condition illustrated in FIGS. 4'and 5 in which the inner end flange 22 of the clamp plate 16 is spaced from the side wall 7 of the channel-shaped member 6, the lugs 14a and 15a being free to slide along the channel-shaped member 6. When substantial ,work is to be done with implements, such as triangles or protractors, at any selected location of the T-square S, or where the use of both hands is necessary or desirable, the T-square S may be locked in the selected position by simply rotating the lever 28 to the position shown in FIGS. 2 and 3, at which the end flange 22 of the clamp member '16 engages the side wall 7 of the channelshaped member 6, and the faces 14b and 15b of the lugs 14a and 15a are forced against the side wall 8 of the channel-shaped member 6.

I claim:

1. A drawing board and T-square combination comprising: a drawing board having an elongated channel at one edge thereof, said channel having opposed parallel side walls, and a T-square slidably disposable upon said 1 board and including a head and a blade projecting from said head in overlying relation to said board, said head having guide means slidable in said channel for maintaining said blade in right angular relation to said channel, lock means cooperative with said guide means for re- 7 leasably clamping said head in a fixed position with rein said groove, and operating means carried by said head forces between a clamping member, such as the member In the use of the drawing board and T-square as de- I scribed above, it will be understood that in normal usage the clamping or locking means L may be released so that the T-square S is easily slidable along the upper surand-acting on said another flange for sliding said clamp plate to move said first-mentioned flange into engagement with a side wall of said channel and to force said guide means into engagement with the other side wall of said channel, said operating means including a lever pivotally mounted on said head and-having a cam pin engageable with a surface of said another flange of said clamp plate for shifting said clamp plate responsive to pivotal movement of said lever, said cam pin and the axis of pivotal movement of said lever being in a plane at least normal to said surface when said lock means is operated to clamp'said T-square to said channel.

, References Cited UNITED STATES PATENTS 2s2,24s 7/1 883 Weidenmann 33-76 1,020,253 3/1912 Blair 3376 1,593,097 7/1926 0rd 33--76 FOREIGN PATENTS 493,735 6/1950 Belgium.

HA'R-RY N. HAROIAN, Primary Examiner

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