GB1595748A - Folding square - Google Patents

Description

(54) FOLDING SQUARE (71) We, MASAZO NAKAMURA of 50, Higashinocho, Dainoji-cho, Minami-ku, Osaka-shi, Osaka-fu, Japan, and TOSHIAKI HIRATANI of 38, Higashinocho, Daihoji-cho, Minami-ku, Osaka-shi, Osaka-fu, Japan, both Japanese citizens, do hereby declare the invention, for which we pray that a patent may be granted to us, and the rnethod by which it is to be performed, to be particularly described in and by the following statement:- The present invention relates to a folding square for use in construction work or the like to check or lay out right-angles.

An object of this invention is to provide a folding square which can be easily assembled, and folded after use to facilitate carrying.

Another object of this invention is to provide a folding square which can readily establish a right angle and also form smaller angles.

The invention consists in a folding square comprising: two arms pivotably interconnected at a fixed point adjacent respective ones of their ends so as to be capable of forming a right angle between their respective outside edges when unfolded; and an elongate coupling member having one end pivotably mounted at a fixed point on one of said two arms and the other end being releasably securable to the other arm by a securing means mounted on said other arm at a fixed point, and said coupling member having a slot to permit said securing means to slide therealong and enable the square to be folded.

One or each arm may be provided with an extension arm mounted therein so as to be slidable therealong. The or each extension arm may have adjacent its outer end a surface aligned with the outside edge of the respective arm.

The folding square may comprise one or more levels for checking whether surfaces are horizontal.

In order that the invention may be more readily understood reference will now be made to the accompanying drawings, in which: Fig. 1 is a plan view of a folding square embodying this invention; Fig. 2 is a side view of the outer end of the longer arm Fig. 3 is a sectional view taken along the line Ill-Ill in Fig. 1; Fig. 4 is a sectional view of a portion of an extension arm; Fig. 5 is a sectional view taken along the line V-V in Fig. 1 showing a stop member; Fig. 6 is a plan view showing the folding square of Fig. 1 folded up; Fig. 7 is a front view of another construction of stop member; and Fig. 8 is a plan view of the stop member of Fig. 7.

Referring to Figs. 1 to 3 a folding square according to this invention includes two arms, a longer arm 1 and a shorter arm 2 which are both tubular and of rectangular cross-section. The two arms, which pivot with respect to each other about 5 at a fixed point, have inclined or bevelled surfaces at their inner ends which abut against each other so that the outside edge 3 of the longer arm 1 is at right angles to the outside edge 4 of the shorter arm 2.

The axis of pivot 5 lies on an extension of the line of abutment between the abutting surfaces and on, or, preferably, just inwardly of the intersection point of the inside edge 6 of the arm 1 and the inside edge 7 of the arm 2 so that when the two arms are folded, the two inside edges 3, 4 will be parallel to each other. As shown in Fig. 5, the two arms 1 and 2 have projecting portions 8 and 9 respectively, engaging each other with the pivot 5 extending therethrough.

An elongate coupling member 10 constituting a hypotenuse is attached to the upper surfaces of the two arms 1, 2 with one end of the member 10 being mounted on a pivot 12 secured at a fixed point to a support 11 projecting from the inside edge 6 of the arm 1 and the other end of the coupling member 10 being releasably attached to the arm 2 by clamping means 14 provided on a support 13 which projects inwardly from the inside edge 7. The clamping means 14 com prises a threaded shaft 15 located at a fixed point and extending through the support 13 and an elongate straight slot 16 in the coupling member 10, and a knurled lock nut 17 screwed on the shaft 15 (Fig. 3). When the nut is tightened to secure the coupling member 10 to the arm 2, the two arms and the coupling member form an integral instrument.The nut 17 is formed with a projection on its bottom 18 so as to fit in an enlarged recess at the corresponding end of the slot 16 in the coupling member 10.

Arms 1 and 2 have respective open outer ends 19, 20, that is the ends opposite to the abutting surfaces, to receive extension arms 21, 22, respectively, which also are tubular and of a rectangular cross section. the extension arms 21, 22 telescope in the respective arms 1, 2 so that the combined length of the arms 1 and 21, and arms 2 and 22 can be increased as desired. As will be seen in Fig. 4 a ball 25 in a hole in one wall in each extension arm is biassed outwardly of the arm by a spring 24 mounted in a spring support 23 which is threaded in the opposite wall of the extension arm. A plurality of such balls bear against the inner surface of the respective arm 1 or 2 to ensure that the extension arm slides smoothly in that arm.

Each extension arm may be temporarily fixed to its respective arm 1 or 2 by a suitable means such as a screw or a lug 27 similarly biassed by a spring 26. Alternatively, the engagement between each extension arm and its respective outer arm 1 or 2 may be adapted to be relatively tight so that the extension arms can be pulled out only by force. Each extension arm 21 or 22 is provided at its outer end with an enlarged portion or head having an outside edge 28 or 29 aligned with the outside edge 3 or 4 of the arm 1 or 2. The heads also serve as stop pers for preventing the extension arms from telescoping fully into the respective arm 1 or 2.

In the shorter arm 2 and the head of the extension arm 22 there is provided a rod 30, 31, constituting an engaging member or a stop, respectively, at positions equally spaced from the outside edges 4 of the arm 2 and a line extended therefrom, respectively.

As shown in Fig. 5, the rod 30 is slidably mounted in a lateral hole 32 in the arm 2 and held captive against axial movement by a ball 34 which is biassed by a spring 37 mounted on a setscrew 36 in another lateral hole 35 which is disposed perpendicular to the lateral hole 32. The ball 34 is located in and engages one of two annular recesses 33, 33' formed in the rod 30. When necessary, the rod 30 is placed in its operative position as in Fig. 5 where its lower end projects from the bottom surface of the arm 2 with the ball 34 located in the recess 33. When not needed, the rod 30 is pushed in until the ball 34 engages the other recess 33'. The rod 31 on the extension arm 22 is similarly arranged and constructed.

Fig. 6 shows how the folding square is folded. The lock nut 17 is first loosened.

The arm 2 is now turnable about the pivot 5 as the shaft 15 slides in the slot 16 in the coupling member 10. The arm 2 turns counterclockwise toward the arm 1 in Fig. 1 whereas the coupling member 10 turns clockwise about the pivot 12 with the shaft 15 moving towards the other end of the slot 16. The arm 2 moves to a position where it is parallel with the arm 1 and the coupling member 10 is located over the two arms as in Fig. 6. The nut 17 is retightened to clamp the arms 1, 2 and the coupling member 10 together.

To reassemble the square thus folded into its operative position, the reverse procedure to the above is carried out with the lock nut 1 7 being retightened in its original position.

An exact right angle is now formed between the outside edge 3 of the arm 1 and the outside edge 4 of the arm 2.

The square thus assembled is used to check or test right angles. In doing so, each extension arm 21, 22 can be pulled out ot the respective arm 1, 2 to extend the length thereof, as desired. When necessary, the arm 2 may be set on a workpiece to be checked, such as lumber or the like, with the rods 30 and 31 engaging one ofits edges and the arm 1 being used to check or lay out a right angle.

The coupling member 10 with the straight slot 16 as illustrated is simple and low in cost. However, the coupling member may be formed with an arcuate slot of a relatively large radius. Such an arcuate slot ensures a smoother folding action.

The preferred embodiment is provided with three levels: the first one 38 is on the inside edge 6 of the arm 1, the second one 38' is on the inside edge 7 of the arm 2, and the third one 39 on the top surface of the arm 1. When using this square in mounting a window frame, for example, these levels may be used to check whether frame parts are horizontal.

Since the support 11 projects from the inside edge 6 of the arm 1, a space exists between the two arms 1 and 2 when the square is folded up. This space accommodates the levels 38 and 38' and affords them protection.

Conveniently, dots H and J may be engraved on the outside edge 3 of the arm 1 and the outside edge 4 of the arm 2, respectively, at such positions that the ratio of the distance from the corner edge of the square to dot H to the distance from that corner edge to dot J will be 4:3. The accuracy of the right angle of this folding square can be checked by measuring the distance between dots H and J to see that it is in the ratio of 5:4 and 5:3 with respect to the former and latter distances, respectively. The outside edges 3 and 4 may also be graduated to use both arms also as a scale.

The extension arm 22 is formed with a recess 40 in its top surface at the outer end so that it can be easily pulled out by a finger.

A reference line 41 is marked on the arm 2 and an angle scale 42 is graduated on the coupling member 10. By aligning the reference line 41 with a desired angle and tightening the lock nut 17, the desired angle can be established between the outside edges 3 and 4. The square can thus be used to check or lay out a desired angle smaller than right angle.

Figs. 7 and 8 show a variation of the engaging member on the arm 2. The outside edge 29 of the enlarged end of the extension arm 22 is formed with a dovetail groove 44 in which an engaging member or stop 45 is slidably mounted. It is secured to the extension arm 22 by a setscrew 47 extending through an axial slot 46 formed in the stop 45. When necessary, the stop 45 is pushed out so as to project from the underside of the arm 22 as shown in Fig. 7. When not in use, the set screw 47 is loosened and the stop 45 is pushed into its normal non-projecting position.

The folding square may be made of stainless steel, but preferably is made of aluminium because of its light weight and ease of machining.

It will be understood from the foregoing that the folding square is easy to fold and handy to carry when folded and that it can establish a right angle and smaller angles exactly between two arms coupled to each other.

While this invention has been described with reference to a preferred embodiment, it is to be understood that various modifications may be made without departing from the scope of the following claims.

WHAT WE CLAIM IS: 1. A folding square comprising: - two arms pivotably interconnected at a fixed point adjacent respective ones of their ends so as to be capable of forming a right angle between their respective outside edges when unfolded; and - an elongate coupling member having one end pivotably mounted at a fixed point on one of said two arms and the other end being releasably securable to the other arm by a securing means mounted on said other arm at a fixed point, and said coupling member having a slot to permit said securing means to slide therealong and enable the square to be folded.

2. A folding square as claimed in claim 1, wherein said slot is an arcuate slot.

3. A folding square as claimed in claim 1 or 2, wherein one or each arm is provided with an extension arm mounted therein so as to be slidable therealong, one or each extension arm having adjacent its outer end a surface aligned with the outside edge of the respective arm.

4. A folding square as claimed in claim 3, wherein each arm is tubular, has a rectangular cross secticn and is open at its outer end to receive the respective extension arm.

5. A folding square as claimed in claim 3 or 4, wherein a stop member is provided on one of said arms and on the respective extension arm.

6. A folding square as claimed in any one of the preceding claims, further comprising at least one level.

7. A folding square substantially as hereinbefore described with reference to Figures 1 to 6, or Figures 1 to 6 as modified by Figures 7 and 8 of the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (7)

**WARNING** start of CLMS field may overlap end of DESC **. checked by measuring the distance between dots H and J to see that it is in the ratio of 5:4 and 5:3 with respect to the former and latter distances, respectively. The outside edges 3 and 4 may also be graduated to use both arms also as a scale. The extension arm 22 is formed with a recess 40 in its top surface at the outer end so that it can be easily pulled out by a finger. A reference line 41 is marked on the arm 2 and an angle scale 42 is graduated on the coupling member 10. By aligning the reference line 41 with a desired angle and tightening the lock nut 17, the desired angle can be established between the outside edges 3 and 4. The square can thus be used to check or lay out a desired angle smaller than right angle. Figs. 7 and 8 show a variation of the engaging member on the arm 2. The outside edge 29 of the enlarged end of the extension arm 22 is formed with a dovetail groove 44 in which an engaging member or stop 45 is slidably mounted. It is secured to the extension arm 22 by a setscrew 47 extending through an axial slot 46 formed in the stop 45. When necessary, the stop 45 is pushed out so as to project from the underside of the arm 22 as shown in Fig. 7. When not in use, the set screw 47 is loosened and the stop 45 is pushed into its normal non-projecting position. The folding square may be made of stainless steel, but preferably is made of aluminium because of its light weight and ease of machining. It will be understood from the foregoing that the folding square is easy to fold and handy to carry when folded and that it can establish a right angle and smaller angles exactly between two arms coupled to each other. While this invention has been described with reference to a preferred embodiment, it is to be understood that various modifications may be made without departing from the scope of the following claims. WHAT WE CLAIM IS:

1. A folding square comprising: - two arms pivotably interconnected at a fixed point adjacent respective ones of their ends so as to be capable of forming a right angle between their respective outside edges when unfolded; and - an elongate coupling member having one end pivotably mounted at a fixed point on one of said two arms and the other end being releasably securable to the other arm by a securing means mounted on said other arm at a fixed point, and said coupling member having a slot to permit said securing means to slide therealong and enable the square to be folded.

2. A folding square as claimed in claim 1, wherein said slot is an arcuate slot.

3. A folding square as claimed in claim 1 or 2, wherein one or each arm is provided with an extension arm mounted therein so as to be slidable therealong, one or each extension arm having adjacent its outer end a surface aligned with the outside edge of the respective arm.

4. A folding square as claimed in claim 3, wherein each arm is tubular, has a rectangular cross secticn and is open at its outer end to receive the respective extension arm.

5. A folding square as claimed in claim 3 or 4, wherein a stop member is provided on one of said arms and on the respective extension arm.

6. A folding square as claimed in any one of the preceding claims, further comprising at least one level.

7. A folding square substantially as hereinbefore described with reference to Figures 1 to 6, or Figures 1 to 6 as modified by Figures 7 and 8 of the accompanying drawings.