US2574463A - T-square securing means - Google Patents

Description

Nov. 13, 1951 H. A. CHAPIN 2,574,463

T SQUARE SECURING MEANS Filed DEC. 25, 1946 2 SHEETSSHEET 2 *2 S: k) a T? I A A%% Patented Nov. 13, 1951 UNITED STATES PATENT OFFlCE T-SQUARE SECURING MEANS Harold Addison Chapin, San Jose, Calif.

Application December 23, 1946, Serial No. 717,875

2 Claims.

The present invention relates to means for holding the head of a T square firmly and slidably against the side of a drafting-board when in use.

As heretofore made the T square is held in contact with the board by pressure of the hand and sometimes will be allowed to slide inadvertently over a line previously made in ink and still fresh, in such a manner as to smear the ink and ruin the drawing.

One object of the invention is to provide a device that can be easily and quickly attached to the board and square that will effectually prevent its accidentally slipping and hold the blade of the square at right-angles to the board.

Another object of the invention is to provide resiliently controlled means for holding the square in position and instantly released for permitting the easy manipulation of the square on the board and at the same time prevent the tipping of the square on the board.

It is also an object of the invention to provide a device of the character indicated that can be easily manipulated by the fingers of one hand.

In the drawing:

Figure 1 is a top plan view of my invention as attached to a square and positioned on a board, parts being broken away.

Figure 2 is an enlarged sectional view on line 22 on Figure 1.

Figure 3 is an enlarged top plan view of my invention as arrangtd on a T square.

Figure 4 is a bottom plan view of a square in position on a board, parts being broken away, and embodying my invention.

Figure 5 is a cross sectional view on the line 5-5 of Figure 2.

Referring now more particularly to the drawing, I show at l a drafting board fitted on one edge with a strip of metal 2 to act as a smooth and true edge for the T square to slide on, this metal strip being slightly wider than the thickness of the blade head 4 of the T square in conjunction with which it is used. The opposite edge of the board is fitted with a strip of metal 3, this latter strip being in the form of an angle bar, and placed with its top surface lying fiush with the top surface of the board as shown.

The head of the T square, as mentioned, is shown at 4 with the blade showing at 5, the head end of the blade having a sheet of sheet metal 6 bent thereover as shown to provide clearance for the blade on the board and permit its sliding freely thereover, and to provide a sliding surface for the member hereinafter described.

Passing through the blade head 4 and overlying end of blade 5 is a bolt 1 supporting a knob 8 in fixed relation to the blade head 4 and blade 5, the said knob 8 having a groove 9 formed in its bottom end to permit the strap H) to slide therethrough. I

The strap I0 is a fiat strip of sheet metal lying fiat on the top surface of the blade 5 in parallel relation therewith and along its median line, passing through the groove 9 and terminating in a strap head I l. The head I l is a heavy piece of sheet-metal bent into a U-shape when viewed endwise, the space between the top and bottom leaves of the U-shaped member being somewhat greater than the thickness of the strap it which it encompasses and to which it is bolted as at l2. In this space between the top and bottom leaves of the U-shaped member is placed a spring is with one end bearing against the member and the other end bearing against the adjacent edge of the metal member 6. Disposing the spring l3 in this manner enables it to urge the strap head I l and consequently the strap l0 outwardly with respect to the blade 5.

The strap ID has a slot [4 formed therein through which the bolt '1 passes and which permits the strap to slide on blade 5. Adjacent the free end of blade 5 is bolted as at I5 a shoe It, a slot I! in blade 5 allowing the bolt [6 to slide backwards and forwards in the blade, the shoe I6 being supported below the blade 5 to have sliding engagement with the angle bar 3.

Normally the spring l3 urges the shoe l6 against the angle bar 3 below its top flange and thus holds the blade head 4 snugly against the metal strip 2 and holds the T square firmly in position. By hooking the thumb of the left hand around the knob 8 the fingers of that hand may be freely used to press upon the strap head II and so re lease the spring pressure forcing the shoe it into contact with the metal strip 3 and permitting the free movement of the blade 5.

The slots [4 and I! permit the strap in to be moved lengthwise of the blade 5 for releasing the pressure against strip 3, and also to permit the pressure of spring l3 to return that pressure instantly when so desired by the operator.

Two guide members, preferably resilient, are shown at I8l8 fastened to the underside of the metal strip 2 to pass under and bear against the bottom front edge of the head 4. These guide members operate to hold the blade head 4 in its proper relation to the top surface of the drafting board, that is, in most cases with its top surface aligned fiush with the top surface of the board.

it is to be noted that the sheet metal strip 6 which is disposed over the head end of the blade 5 provides reinforcing bearings spaced in the direction of the length of the bolt 1 to aid in sustaining the same when the T-square is actuated by the knob 8.

In the manner described the T-square may be instantly adjusted along the length of the board and yet at. all times it is held against accidental movement:

Having thus described my invention, what I claim as new and desire to secure by Letters Patent, is:

l. The combination of a T-square including a;-

blade, and a transversely extending head secured to one end thereof and having a straight inner wall for engagement with the edge of adrafting board, a U-shaped holder of relatively thin stock carrying the head end of the blade, one leg of the U-shaped holder being disposed between the T-square head and the blade whereby to space the latter slightly aboveth'e plane of the top of a drafting board, an elongated'bolt extending through said head, blade and blade holder; a knob mounted on the projected-end of said bolt above said blade and head, an, elongated flat metal strap extending lengthwise of saidblade, one endof said strap normally projectingbeyond the outer edge of said head and having a down-turned portion disposed in opposition to the outer edge of said head, said strap having a lineal slot through which saidknob carrying bolt-extends, a vertically extending pin secured to the strap adjacent itsrotheriend', the;

blade having, a slot through which said pin extends to a point below the undersurfacevof said blade, a shoe carried by the lower end of-said pin and positioned to engage the edge ofthe drafting board opposite to that engaged by the T-square head, said knob having a groove-in its 4 bottom surface through which said strap is adapted to slide, and spring means interposed between the down-turned end of said strap and the rear edge of said blade and its U-shaped holder.

2. The combination of a T-square including a blade, and a transversely extending head secured to one end thereof and having a straight inner wall for engagement with the edge of a drafting board,,an elongated boltextendingrthrough said head and=bladeand projecting above the top surface of the latter, a knob mounted on the projected end of said bolt above said blade and head, an elongated flat metal strap extending lengthwise 'of said blade, one end of said strap normally projecting beyond the outer edge of said head and having a down-turned portion disposed irropposition to the outer edge of said head, said strap having a lineal slot through which said knob-carrying bolt extends, a depending draftin board-edge-engaging shoe element carried by said strap-at the endremote from the knob, said blade and strap havin 00- operating guide means-adjacent said last men-- tioned end of said strap.

HAROLD ADDISON CHAPIN.

REFERENCES CITED Thefollbwlngreferences-'are'of record in thefile'ofthis patent:

UNITED STATES PATENTS Number Name Date 282,248. Weidenmann' July 31-, 1883 v 1,419,354 Boon- -i. June 13, 1922' 2,085,304- Farrell June 29, 193'! 2,326,301 Leffel- Mag 10, 1943 FOREIGN PATENTS Number Country Date 21,402 Great Britain Sept. 20, 1909= 376,843 Germany June 5, 1923

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