Tolerances
- Last UpdatedAug 14, 2025
- 2 minute read
As well as distinguishing between hard and soft clashing items, the checking utility recognises three categories of clash between them, depending on how far the two primitives intrude on each other's allocated space.
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Touch Gap |
A touch where the primitives either overlap by less than the amount needed to cause a clash or are separated at their closest point by less than a specified distance which can mean that one item is resting upon another as intended, or it can indicate a problem. |
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Overlap |
A physical clash where the primitive volumes overlap by more than a specified amount which means that a definite interference exists. |
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Clearance |
A clearance where the primitives are separated at their closest point by more than the amount necessary to constitute a touch but less than a specified clearance distance which represents a near miss, which you may want to investigate. |
These three classes are illustrated below for the clash specifications:
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Touch limits: 5mm overlap to 2mm gap
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Clearance limit: 8mm
so that the following criteria apply:
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If the items overlap by more than 5mm, a clash is reported
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If the items overlap by less than 5mm, a touch is reported
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If the items do not overlap but are separated by less than 2mm, a touch is reported
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If the items are separated by more than 2mm but less than 8mm, a clearance is reported
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If the items are separated by more than 8mm, no interference is found.
