Select the sketch, click on the ellipsis (three dots) next to the Data Map Mode property, and choose the top face of the second pad again. To fix the issue, the third sketch should be mapped to the top face again. The third sketch is attached to Face13 as it originally was, but since this face is now on the side (not at the top), the sketch follows its orientation and now is incorrectly positioned.ħ. The problem appears to be that when the second sketch was modified, the top face of the second pad was renamed from Face13 to Face14.
![freecad offset freecad offset](https://www.xsim.info/articles/FreeCAD/images/Mod-Part/Part_Offset2D3.png)
This results in an invalid pad, as this pad would be disconnected from the rest of the PartDesign Body, which is not allowed. The third sketch, instead of being supported by the top face of the second pad, appears in a strange place, with its normal oriented towards the X direction. By making visible the third sketch and pad, it is clear that the computation of the new solid did not proceed correctly. By doing this, the second pad will recompute correctly, however, when looking at the tree view, an error will be indicated in the third pad.Ħ. Now, double click the second sketch again, and adjust its points so that a portion of it is outside the limits defined by the first pad. The third sketch and pad will stay in the same place.ĥ. Now, double click the second sketch, and modify it so that its length is along the X direction doing this will recreate the second pad. Select the top face of the previous extrusion, and once again create a sketch, and a pad.Ĥ. Select the top face of the previous solid, and then use PartDesign NewSketch to draw another sketch then perform a second pad.ģ. In the PartDesign Workbench, create a PartDesign Body, then use PartDesign NewSketch and select the XY plane to draw the base sketch then perform a PartDesign Pad to create a first solid.Ģ. In TechDraw, the user is advised to add dimensions only when the 3D model is complete and won't be modified further.ġ. Use of supporting datum objects like planes and local coordinate systems is strongly recommended to produce models that aren't easily subject to such topological errors. In PartDesign, the user is advised to follow the best practices discussed in the feature editing page. The topological naming problem most often affects and confuses new users of FreeCAD. Forum thread: Topological Naming, My Take.As of FreeCAD 0.19 there are ongoing efforts to improve the core handling of shapes in order to reduce or eliminate such issues. The topological naming issue is a complex problem in CAD modelling that stems from the way the internal FreeCAD routines handle updates of the geometrical shapes created with the OCCT kernel.
![freecad offset freecad offset](https://www.xsim.info/articles/FreeCAD/images/Part_Offset5.png)