Please note follows when using automatic 3D modeling:

1. Do not make the drawing to be too complicated. Keep the number of total entities less than 100 if possible.
2. It is better that do not use the third view if only two views can describe the solid exactly.
3. Avoid cross intersections of hidden features as possible, or omit hidden feaures if possible.
4. Do not project through holes as possible except they have different segments.
5. Avoid intersections of curve surfaces as possible.
6. Avoid non-orthogonal slope.
7. It is better that chamfering or filleting after modeling.
8. Spline modeling via another process is a suggestion.
9. Because of limited memory, it will cause crashes if it takes too long for modeling. It is recommended to escape by using "ESC" key, and then finish modeling by using semi-automatic modeling functions.