Hello, the calculation method of free tolerance of parts depends on the tolerance standards used, such as ISO tolerance, ANSI tolerance, JIS tolerance and so on. Generally speaking, the free tolerance refers to the difference between the maximum size and the minimum size of a part, which is usually calculated by using the following formula:

　　Free Tolerance = Maximum Size Minimum Size

　　For example, if the maximum size of a part is 50 mm and the minimum size is 49 mm, its free tolerance is:

　　Free tolerance =50 mm 49 mm =1 mm.

　　It should be noted that different tolerance standards and application fields may have different tolerance calculation methods and accuracy requirements, so it needs to be selected and applied according to specific conditions in actual engineering design.

　　Limit deviation of linear dimension of free tolerance The numerical tolerance grade size is divided into 0.5 ~ 3 > 3 ~ 6 > 6 ~ 30 > 30 ~ 120 > 120 ~ 400 > 400 ~ 1000 > 1000 ~ 2000 ~ 4000 F (precision grade) 0.05 0.05. 0.1 0.1 0.2 0.3 0.5 0.8 1.2 2 C (coarse grade) ±0.2 ±0.3 ±0.5 ±0.8 ±1.2 ±2 ±3 ±4 v (coarsest grade) 0.5 1.5 2.5 4 6 8 Table 2 Limit deviation between radius of rounding and chamfer height. Numerical tolerance grade size is divided into 0.5 ~ 3 > 3 ~ 6 > 6 ~ 30 > 30 F (precision grade) ±0.2 ±0.5 ±1 ±2 m (medium grade) C (rough grade). Table 3 numerical tolerance grade length of limit deviation of angular dimension ≤ 10 > 10 ~ 50 > 50 ~ 120 > 120 ~ 400 > 400 f (precision grade) ±1° ±30 ±20 ±10 ±5 m (medium grade) c (rough grade) 1 30 1 30. 3 2 1 30 20 The length of the angular dimension is determined according to the length of the short side of the angle, and the conic angle is determined according to the length of the conic prime line.