Combination square is a common measuring instrument used for angle, length, height measurement and center positioning in machining and wood mold processing.

This paper introduces the spirit level measurement method

The right angle precision square is mainly used for the inspection and marking of the right angle of the workpiece. When installing and adjusting the equipment, the verticality of the relevant surface of the part or component is inspected.

Before using it, you must first make a school pair, calibrate the spirit level tools. Place it on a flat wall, draw a line, call the horizontal ruler, put it on the line you originally painted. If it is capable of coincidence, it is also possible to ensure that the measured data is also accurate.

A square tool is made for drawing or checking right angles, and sometimes for scribing lines. The square tools are characterized by high precision, good stability and easy maintenance

The accuracy of the spirit level refers to the axial movement of the level bubble and the inclination angle when the center of the bubble coincides with the symmetrical center of the left and right marking lines when the level is at a specified horizontal inclination angle.