1. Paper formats can be divided into five types according to size, and drawing formats are coded as A0, A 1, A2, A3 and A4 respectively. There must be a title bar in the lower right corner of the picture frame, and the direction of the text in the title bar should be consistent with the direction of the picture.

2. There are eight kinds of drawing lines: thick solid line, thin solid line, wavy line, double broken line, dashed line, thin dashed line, thick dashed line and double dashed line.

3. In the drawing, the visible contour lines of machine parts are drawn with thick solid lines, the invisible contour lines are drawn with dotted lines, dimension line and dimension line are drawn with thin solid lines, and the symmetrical center lines and axes are drawn with thin dotted lines. The width of the dashed line, thin solid line and thin dashed line is about 1/3 of that of the thick solid line.

4. Proportion refers to the ratio of graphic size to actual size in drawing.

5. The ratio of1:2 means that the physical size is twice the size of the drawing, which is a reduced ratio.

Extended data:

Proportion is the ratio of the linear dimensions of the corresponding elements in a figure and an object. When the pattern needs to be drawn in proportion, the appropriate proportion should be selected from the specified series. In order to get the realism of the physical dimensions from the drawings, the original scale (1: 1) should be adopted as far as possible. When the parts are too large or too small, you can choose the reduction or enlargement ratio specified in the table, but the actual size must be indicated when dimensioning.

Generally speaking, all views of the same part should be drawn at the same scale and filled in the title bar. When a view needs to adopt a different scale, the scale can be marked below or to the right of the view name.