Set diameter tolerances

Extended modules > Advanced Machining > Set diameter tolerances

Diameter or radius dimensions for the cylindrical faces of the holes as specified by Creo Elements/Direct Annotation 3D are transferred as tolerances to the CAM system.

Creo Elements/Direct Annotation 3D currently supports the following three types of tolerances:

• Limit

• Upper/Lower

• Plus/Minus

User-entered numeric values are exported as a diameter value with upper and lower tolerances. If a radius is specified, its value is doubled.

Creo Elements/Direct Modeling does not support ISO-tolerances as elements of the data structure. However, a workaround overcomes this limitation by allowing you to specify the ISO-tolerance using the postfix text of the dimension.

Creo Elements/Direct Machining knows the full range of ISO-tolerance qualities:

"01", "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "10", "11", "12", "13", "14",
"15", "16", "17", "18"

and the tolerance fields:

"A", "B", "C", "CD", "D", "E", "EF", "F", "FG", "G", "H", "J", "JS",
"K", "M", "N", "P", "R", "S", "T", "U", "V", "W", "X", "Y", "Z",
"ZA", "ZB", "ZC",
"a", "b", "c", "cd", "d", "e", "ef", "f", "fg", "g", "h", "j", "js",
"k", "m", "n", "p", "r", "s", "t", "u", "v", "w", "x", "y", "z",
"za", "zb", "zc"

If a radius dimension is specified, the ISO tolerance is applied to the diameter also, although this may result in different numerical tolerances because ISO tolerances are governed by a geometrical sequence (that is, 10H7 means 10.000 - 10.018 but 20H7 is 20.000 - 20.021)

For technical reasons, it is therefore recommended to use the ISO tolerances as this will convey the information qualitatively rather than quantitatively, which may not lend itself to geometrical scaling.

Therefore, the process of specifying a diameter tolerance can be compared to adding a diameter or radius dimension to the cylindrical face.