Description
Unsmooth faces are entities on which some operations (for example Shell and Offset) cannot be performed because they are not sufficiently smooth.
Recommendation
If the above operations need to be performed on these faces, it is recommended to select the Split unsmooth faces up to x faces parameter. The first process smooths all corners up to 6 degrees without splitting the face. If this fails, the Split operation is performed on the unsmooth points. Using this parameter, you can limit the number of faces that will be created for one unsmooth face to prevent the creation of a large number of faces. For example, if one or more faces from the unsmooth faces has a number of unsmooth points which will force the tool to split the face into a larger number of faces than defined in the parameter, the face will not be split which is preferable to getting a large number of unusable faces.
The face below is an unsmooth face:
It is split into three faces by the Check & Fix Entities tool.
Unsolved Cases
Use the Fair unsmooth faces option but take into account that fairing unsmooth faces may change the shape of the faces.