Open CASCADE, the 3D modelling kernel
3D modeling & numerical simulation



Tolerance Management

To produce a closed shell, Sewing allows to specify the value of working tolerance exceeding the size of small faces belonging to the shape.

However, if we produce an open shell it is possible to get incorrect sewing results for a large value of working tolerance (if the value of working tolerance exceeds the size of faces lying on an open boundary).

The following recomendations can be proposed to the users for tuning-up the sewing process:

- Use as small working tolerance as possible. This will reduce the sewing time and, consequently, the number of incorrectly sewed edges for shells with free boundaries.

- Use as large minimal tolerance as possible. This will reduce the number of small geometry in the shape, both original and appearing after cutting.

- When a shell with holes (free boundaries) is expected as a result of sewing then the working tolerance should be set to a value not greater than the size of the smallest element (edge) or smallest distance between elements of such free boundary. Otherwise the free boundary may be sewed only partially.

- It should also be mentioned that the Sewing algorithm is unable to understand which small (less than working tolerance) free boundary should be kept and which should be sewed.


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