GB2068571A - Right Angle Setting and/or Checking Instrument - Google Patents

Abstract

An instrument comprises a rigid member AB having attached at the in mid point X between its ends A, B a pivoted rigid arm CX, where AXB is a straight line with AX and BX equal in length, and CX is equal in length to AX and BX. The arm CX pivots in a plane common to AXB, in such a manner that the angle ACB is a right angle, regardless of the attitude of the arm CX to the main member AB. <IMAGE>

Description

SPECIFICATION Right Angle Setting and/or Checking Instrument General The invention relates to an instrument for setting or checking right angles.

In the building and construction industry the need to set out or check right angles, particularly in the horizontal plane, is usually effected by temporary squares being constructed from materials available on site, which tend to be bulky, and awkward for transportation and storage.

This invention relates to a permanent instrument for the setting out or checking of right angles, which is adjustable enabling its use in restricted places, and in any attitude.

It is also compact in its closed position to facilitate easy transportation and storage.

Its essentials are based on a geometric principle which is that two lines joining any point on the circumference of a semi-circle with the extremities of the base form a right angle.

By way of an example one embodiment of the instrument according to the invention is shown in diagrammatic form in Figure 1.

Referring to Figure 1 A to B is a rigid member having attached at its centre point a pivoted rigid arm CX. Where AXB is a straight line, with XA, and XB of equal length, and the arm XC equal in length to XA and XB and pivoted at point?(, swinging in the same plane as member AB.

Thus in all positions of point C relative to AXB the angle formed by points ACB is a right angle.

Right Angle Setting and/or Checking Instrument A typical example of the use of this particular embodiment of the instrument would be in checking the squareness of one vertical wall to another vertical wall where the point C on the instrument would be placed at the junction of the two walls, where upon point A and B on the instrument when held in a horizontal plane should touch the two walls forming the right angle.

See Figure 2.

Claims

1. An instrument for checking or measuring right angles which when in its working mode, comprises a rigid member having pivoted at a point central to a line joining the two extremities, a rigid member whose length from pivot to extremity is equal to half the length of the main member, and is capable of swinging on a plane common to the axis of the main member in such a way that a line joining the three extremities of the members will prescribe a right angle, regardless of the attitude of the swinging member.

2. As in claim (1) the ends of the members being formed as tubular or cylindrical pieces whose axes are parallel to the central pivot axis.

3. As in the preceding claims, and having affixed to the extremities of the members Magnetic, Suction, or Mechanical holding devices.

4. A method for setting or checking right angles in structures by means of a pivotted assembly as in claim (1).

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

Claims (4)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Right Angle Setting and/or Checking Instrument General The invention relates to an instrument for setting or checking right angles. In the building and construction industry the need to set out or check right angles, particularly in the horizontal plane, is usually effected by temporary squares being constructed from materials available on site, which tend to be bulky, and awkward for transportation and storage. This invention relates to a permanent instrument for the setting out or checking of right angles, which is adjustable enabling its use in restricted places, and in any attitude. It is also compact in its closed position to facilitate easy transportation and storage. Its essentials are based on a geometric principle which is that two lines joining any point on the circumference of a semi-circle with the extremities of the base form a right angle. By way of an example one embodiment of the instrument according to the invention is shown in diagrammatic form in Figure 1. Referring to Figure 1 A to B is a rigid member having attached at its centre point a pivoted rigid arm CX. Where AXB is a straight line, with XA, and XB of equal length, and the arm XC equal in length to XA and XB and pivoted at point?(, swinging in the same plane as member AB. Thus in all positions of point C relative to AXB the angle formed by points ACB is a right angle. Right Angle Setting and/or Checking Instrument A typical example of the use of this particular embodiment of the instrument would be in checking the squareness of one vertical wall to another vertical wall where the point C on the instrument would be placed at the junction of the two walls, where upon point A and B on the instrument when held in a horizontal plane should touch the two walls forming the right angle. See Figure 2. Claims

1. An instrument for checking or measuring right angles which when in its working mode, comprises a rigid member having pivoted at a point central to a line joining the two extremities, a rigid member whose length from pivot to extremity is equal to half the length of the main member, and is capable of swinging on a plane common to the axis of the main member in such a way that a line joining the three extremities of the members will prescribe a right angle, regardless of the attitude of the swinging member.

2. As in claim (1) the ends of the members being formed as tubular or cylindrical pieces whose axes are parallel to the central pivot axis.

3. As in the preceding claims, and having affixed to the extremities of the members Magnetic, Suction, or Mechanical holding devices.

4. A method for setting or checking right angles in structures by means of a pivotted assembly as in claim (1).