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I thought I would knock some dust off my drafting skills after a small chat with @captain_[email protected]
Seeing this image on the tutorial made me realize, FreeCAD seems to be a Technical Geometry Super-Suite. It makes sense that CAD would grow to include all of these things. But I thought sharing the initial perspective of some one who hasn't looked at this stuff in about 18 years might be interesting.
Granted I'm not actually familiar with most of this stuff, and none of it from the POV of FreeCAD. If this can deliver 10% of what I'm looking at, I'm in for a treat.
I've seen it do things like that for two reasons:
If your change causes the number or arrangement of faces to change, this currently breaks things. This is what people in this thread talking about the topological naming issue are about; it keeps track of which faces are which by giving them names when they are created, and then when another feature is added to that face, it's linked by name. If you go back, edit an earlier step which creates more or fewer faces, it recomputes the model and might name them differently, so features suddenly move.
Sometimes I've had the sketcher just decide to turn a sketch inside out, because sometimes things like tangent constraints have two stable ways to be "fully constrained" or the existing constraints make different shapes with different dimension numbers.
I have seen both issues, when the sketcher starts to play up sometime I add more constraints to try to "anchor" a tangent in a certain direction but it can make the sketch messy The most reliable way I've found to stop it is small incremental changes e.g. say I want the length of a part to change my 40mm I'll change the size in 5mm increments allowing FC to recompute the model between each step. It's fiddly and frustrating but I can live with it, once you get to understand it's quirks Freecad can be very useful