1, we know the hardness of pencils and the uses of 4B, 2B, b, 2A, AB, pencils from the moment we sharpen them.

2. Write imitation song style, because the font required by the drawing is imitation song style. When I first came into contact with the painting class, I wrote imitation song style until I passed the test.

3. Understand the drawing format, starting with drawing No.0 and ending with drawing No.32. Of course, A3A4 paper came later.

4. Establish a preliminary concept of space in connection with the three views.

Basic knowledge of engineering drawing:

No matter what scale is used in drawing, its size should be marked with the real size of the object.

Generally, D = 0.5 and 0.7mm are preferred for thick lines and 1/2 for thin lines.

Basic principles of dimensioning. 1. The actual dimensions of machine parts shall be based on the dimensions marked in the drawings, regardless of the drawing size and drawing accuracy. 2. When the dimensions in the drawing are in millimeters, there is no need to mark the unit of measurement code.