US1485787A - Tau-square guide - Google Patents

Description

Patented lidar. All, 1924.

@NEFF it-@SEM T-SQUARE GUIDE.

Application :filed 'March 26, 1923.

To all whom t may concern.'

Be it known that I, FRANZ KTTEL, a citizen of the Republic of Switzerland, and resident of Lucerne, in the Canton of Lucerne,

Switzerland, have invented'certain new and useful Improvements in T-Square Guides, of which the following is a specification.

rEhe manipulation of loose T-squares along the edges of a drawing board has ever been felt as an inconvenience by every draughtsman, inasrnush as he is necessarily obliged always to use one hand for thepurpose ofpressing the l`square against and cause it to slide along the board in order to draw horizontal l5 or vertical lines and parallels thereto. It

not rarely happens hereby that owing to carelessness in holding or guiding the T- square a fresh line, instead of being drawn parallel, is drawn at an angle to the preceding line. More often, however, foreign bodies become attached to the guiding edge of the drawing board, the T-square being made to slide over these bodies and thereby caused to lose its true bearing. Especially when using large drawing boards, care must be taken that in guiding the drawing pen or pencil along the correspondingly long T- square, the latter, as is frequently the case when operating at its end, is not forced out of its true horizontal position relative to the drawing board, a firm pressure of the T-square against the edge of the board being essential in order to maintain such true horizontal position of the fsquare.

It is the object of the present invention to enable the draughtsman not only to keep the T-square constantly in the required horizontal position, but also to permit of an easy adjustment and fixing of the T-square at any desired point along the edge of the drawing board.

According to my invention l attach to any drawing board a guide-plate of metal adapted to guide and check the movement of a slotted back-square, the latter forming the head of the T-square and being provided with a hand-operated clamping device by means of which the back-square may be moved and fixed in any position within the said guide-plate.

For a clear understanding of the inven- Serial No. 627,747.

tion I refer to the accompanying drawings, in which l,

Fig. 1 shows a side elevation of the T- square-guide as attached to a drawing board, the latter only partly being illustrated;

Fig. 2 shows a section, partly in elevation, of the aforesaid bach-square with the clamping device;

Fig. 3 shows a perspective view of part of a drawing board with the guide-plate secured thereto;

Fig. a shows an elevation, partly in section, of the hand-operated clamping device; Fig. 5 is a lateral section through parts of the device illustrated in Fig. 2l;

Fig. 6 represents a plan view'of the clamping device;

Fig. 7 is a perspective view of the back- 70 square and certain other parts;

F ig. 8 is a sectional view of details, and

Fig. 9 shows a plan view of the backsquare and the guide-plate mounted on a drawing board.

Referring to these drawings, 1 designates a drawing board of any suitable size, to the underside of one edge of which and exactly parallel thereto an angle-shaped guideplate 2 is secured by means of screws 3 en and washers 4. Each end of the guideplate is formed with an internally screwthreaded nave, as at 28, to receive a pin 24 the pointed end of which, when the pin is screwed into the nave, is made to penetrate into the drawing board thus assisting in steadying the plate 2 and preventing any accidental displacement thereof. The guideplate serves for the reception of a backs uare 6 made, for instance, of wood or a0 celluloid and provided with metal strips 7 at its base to make contact with and ensure smooth sliding along the edge of the drawing board l. The central portion of the back-square 6 has recesses 8 formed therein e5 of the shape most clearly shown in Figs. 2 and 7. Mounted within these recesses is a clamping device adapted to secure the back-square in the guide-plate or release it when it is desired to move the back-square along the said guide-plate. A member 9 of wood or other suitable maf/@rial attached to the top of the back-square and covering the recesses 8 forms With the said backsquare the T-square proper.

The aforementioned clamping device coinprises an arm 10, an integral sleeve 11 at one end thereof, and a clamping member 18 at the other end to tightly abut against or clamp the vertical portion of the guideplate, the arm 10 being pivoted to a bridgepiece 12 fitted Within the recesses 8. Also located in these recesses and secured to the back-square 6 is a spring guide 2O carrying a pin 19, this pin receiving one end of a coil spring 17 of which the other end tends to press against the head 16 of the sleeve 11. The screw-threaded head of the sleeve is fitted With a cap 18, the latter and the sleeve thus forming a handle -for operating the clamping device.

By applying pressure upon the cap 18, the arm 10 is made to swing about its pivot at 12 and the clamping member 13 caused to be disengaged from the guideplate 2, so that the back-square 6 and the member 9, that is, the T-square may be freely moved along the guide-plate. As soon as the pressure on the cap 18 is released, the clamping member 13 is once more made to press against the guide-plate and thereby secures the T-square in position. A slot 21 longitudinally arranged in the bottom portion of the back-square and receiving the vertical part of the guide-plate 2 ensures a true parallel movement of the back-square.

Having now fully described my said invention What I claim and desire to secure by Letters Patent is :M

ln a lu-square-guide for drawing boards, the combination, With an angle-shaped guide-plate attached to the underside of the drawing board and parallel to one Working edge thereof, and a longitudinally slotted and centrally recessed back-square Which forms part of the lsquare and is slidably mounted in the guide-plate, of a clamping device for securing the back-square in any position Within the guideplate, the said clamping device comprising an arm pivotally mounted in the recessed part of the backsquare, a handle formed at one end of the arm, a clamping member fashioned at the other end of the arm and abutting against the inner Vside of the vertical member of the guide-plate, and a spring also mounted Within the aforesaid recessed part and tending to press against the handle end of the arm and causing the clamping member to tightly engage the said vertical member of the guide-plate, all as and for the purpose set forth. n

FRANZ KUTTEL. In the presence of- JAMES J. MURPHY, Jr., Een. COLERE WAons.

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