JP3036923U - Compass opening device - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a compass that can draw a precise circle without loosening during use. [Structure] A horizontal female screw is cut on the central body of a leg with a pencil 1, a rotary bolt body 2 to be screwed into this is fitted, and its tip is opened on the central body of a leg with a needle 3. It is formed by penetrating the vertically long window portion 4 and fixing the spherical retaining portion 5.

Description

[Detailed description of the invention]

[0001]

[Industrial applications]

 This invention relates to a compass opening device.

[0002]

[Prior art]

 Conventionally, when drawing a circle on a sheet of paper with a compass, the leg with a needle and the leg with a pencil are opened by the required length.

[0003]

[Problems to be solved by the device]

 However, while drawing a circle, the open leg shank at the top becomes loose and a double circle is made. The reason for this is that the stem of the spread leg is simply studded, and gradually loosens during use.

[0004]

[Means for Solving the Problems]

 Therefore, this invention is to open the compass by its own means without relying on the conventional tacks and the like. In other words, a threaded portion penetrating in the horizontal direction and its fixing device are provided on the central trunks of both the leg with a needle and the leg with a pencil, and the compass is opened by rotating the screw.

[0005]

[Action and Examples]

 A horizontal female screw is cut on the central body of the pencil-equipped leg 1 of the compass A, and a rotary bolt body 2 to be screwed into this is fitted. Further, the tip portion thereof penetrates the vertically long window portion 4 opened in the central body portion of the leg 3 with a needle, and the spherical retaining portion 5 is fixed. The compass opens or closes by turning the operation knob 6 of the rotary bolt body 2 while applying the tips of the leg with needle 3 and the leg with pencil 1 to the ruler B. At this time, the tip of the rotary bolt body 2 penetrates the vertically long window portion 4 and is fixed by the spherical retaining portion 5. Therefore, as the compass A opens and closes, the compass A floats up and down, and the operation can be smoothly performed without difficulty.

[0006]

[Effect of the invention]

 As described above, the present invention is carried out by rotating the rotary bolt body 2 that horizontally penetrates the central body of both legs, not by fixing the open leg of the compass by conventional tacking, so loosen it during use. It provides a useful compass opening device that can set the precise radius length without any risk of failure.

[Brief description of the drawings]

FIG. 1 is a front view (partially sectional view) of a compass of the present invention.

FIG. 2 is a side view of the main part of the compass of the present invention.

[Explanation of symbols]

 1 Leg with pencil 2 Rotating bolt body 3 Leg with needle 4 Longitudinal window 5 Spherical clasp 6 Operation knob 7 Needle 8 Pencil fixing screw 9 Pencil A Compass B Ruler

Claims (1)

[Utility model registration claims] 1. A vertically elongated body in which a female thread is cut on a central body portion of a leg 1 with a pencil, a rotary bolt body 2 to be screwed into the female body is fitted, and a tip portion thereof is opened in a central body portion of a leg 3 with a needle. A compass leg opening device which penetrates the window portion 4 and has a spherical retaining portion 5 fixed thereto.