From FreeCAD Documentation
- A series of simple sketches is easier to manage than a single complex one. For example, a first sketch can be created for the base 3D feature (either a pad or a revolve), while a second one can contain holes or cutouts (pockets). Some details can be left out, to be realized later on as 3D features. You can choose to avoid fillets in your sketch if there are too many, and add them as a 3D feature.
- Always create a closed profile, or your sketch won't produce a solid, but rather a set of open faces. If you don't want some of the objects to be included in the solid creation, turn them to construction elements with the Construction Mode tool.
- Use the Auto constraints feature to limit the number of constraints you'll have to add manually.
- As a general rule, apply geometric constraints first, then dimensional constraints, and lock your sketch last. But remember: rules are made to be broken. If you're having trouble manipulating your sketch, it may be useful to constrain a few objects first before completing your profile.
- If possible, center your sketch to the origin (0,0) with the Lock constraint. If your sketch is not symmetric, locate one of its points to the origin, or choose nice round numbers for the lock distances.
- If you have the possibility to choose between the Length constraint and the Horizontal or Vertical distance constraints, prefer the latter. Horizontal and Vertical distance constraints are computationally cheaper.
- In general, the best constraints to use are: Horizontal and Vertical constraints; Horizontal and Vertical length constraints; point-to-point Tangency. If possible, limit the use of these: the general Length constraint; edge-to-edge Tangency; Point on object constraint; Symmetric constraint.
- If in doubt about the validity of a sketch once it is complete (features turn green), close the Sketcher dialog and use
Validate sketch.
