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42 basic knowledge of mechanical drawing

March 5, 2024

7. When drawing, it is advisable to use the proportion of the original value as much as possible. If necessary, enlarged or reduced proportions can also be used, where 1:2 is the reduction ratio and 2:1 is the enlargement ratio. Regardless of which ratio is used, the actual size of the machine should be indicated on the drawing.


8. The Chinese characters, numbers, and letters written in the design must have neat fonts, clear strokes, even spacing, and neat arrangement. Chinese characters should be written in a long imitation of Song typeface.


9. The three elements of dimensioning are dimension boundaries, dimension lines, and dimension numbers.


10. Symbol in dimension annotation: R represents the radius of the circle, ф Represents the diameter of a circle, S ф Indicates the diameter of the ball.


11. The dimensions on the drawing are the actual dimensions of the parts, and when the dimensions are in millimeters, there is no need to indicate a code or name.


12. When using standard horizontal dimensions, the heading direction of the size numbers should be upward. When labeling vertical dimensions, the heading direction of the dimension numbers should face left. The dimensions of angles are all written in a horizontal position. When any drawing line passes through the dimension number, it must be disconnected