5 ms·

If Blender and FreeCAD could have a baby together then that would be amazing baby.

progbits 4y ago
Blender has nice UX (the new versions, used to be horrible) but sadly what is holding opensource CAD back for me is the poor constraints and parametric modeling backend. Anything beyond simple polyhedra and booleans runs into a problem. Fillets, chamfers, sweeps and lofts don't work well. It's a shame.
- ezst 4y ago
  Things have improved quite a bit in the latest freecad versions, and I remember reading somewhere that the next one promises to solve whatever's left over. My biggest gripe with freecad isn't necessarily that (it's easy enough to work around), but that going back few steps to edit things and apply it forward is very fragile. There are ideas floating around to better handle this workflow but we'll have to see how well that goes (it's probably a very difficult problem to solve with no general solution). In the meantime this gives me a lot of frustration and rework, but, running on Linux, there's no real alternative as far as I can see.
  - jstanley 4y ago
    There is certainly no general solution. Consider: You make a base sketch and pad it up to create a square part with a single hole in the centre. You chamfer the hole. You change the base sketch so that it is now a rectangular part with 2 holes, 1 at the left and 1 at the right. Should the chamfer apply to the left hole, the right hole, or both holes? Obviously there are special cases that FreeCAD doesn't currently handle optimally, but a general solution is impossible without FreeCAD reading your mind. (You could also asy "any of those 3 options is better than trying to apply the chamfer to a random bit of un-chamferable geometry". But a general solution is still impossible.).
    - TheSpiceIsLife 4y ago
      The chamfer applies to the first hole only, unless it is a copy of the first. Any changes to the first hole only apply to the first hole, unless that second hole is a linked copy of the first. ____ Is there an argument against this general solution?
      - jstanley 4y ago
        Who's to say which hole is the "first"?
        mgdlbp 4y ago
        From the user's perspective, the circle that was originally drawn, which wasn't touched when adding a second circle to the sketch. If the original was deleted, then it's unclear (possibly assume the first replacement). IIRC (not testing now) FreeCAD already handles this example sensibly. You can add circles to the sketch and the chamfer stays put. If you delete the circle and add a new one, it appears on the new hole. But if you add a square instead, it moves to a random edge of the rectangular hole. The 'edge' of the rectangular hole is actually a loop of four edges, so this is understandable. Commercial software can fix some of these cases - I don't think the Freecad link branch can, but it does at least detect that the original geometry was deleted and raises an error asking you to reselect instead of allowing things to move around. And unrelated features downstream don't break. Not dissimilar UX to when I mess with something that Fusion can't handle, I say.
        phkahler 4y ago
        If the first is deleted then everything done to it afterward should be gone.
    - tohnjitor 4y ago
      It should gracefully fail and call for the hole feature to be redefined.

Blender has nice UX (the new versions, used to be horrible) but sadly what is holding opensource CAD back for me is the poor constraints and parametric modeling backend. Anything beyond simple polyhedra and booleans runs into a problem. Fillets, chamfers, sweeps and lofts don't work well. It's a shame.

ezst 4y ago
Things have improved quite a bit in the latest freecad versions, and I remember reading somewhere that the next one promises to solve whatever's left over. My biggest gripe with freecad isn't necessarily that (it's easy enough to work around), but that going back few steps to edit things and apply it forward is very fragile. There are ideas floating around to better handle this workflow but we'll have to see how well that goes (it's probably a very difficult problem to solve with no general solution). In the meantime this gives me a lot of frustration and rework, but, running on Linux, there's no real alternative as far as I can see.
- jstanley 4y ago
  There is certainly no general solution. Consider: You make a base sketch and pad it up to create a square part with a single hole in the centre. You chamfer the hole. You change the base sketch so that it is now a rectangular part with 2 holes, 1 at the left and 1 at the right. Should the chamfer apply to the left hole, the right hole, or both holes? Obviously there are special cases that FreeCAD doesn't currently handle optimally, but a general solution is impossible without FreeCAD reading your mind. (You could also asy "any of those 3 options is better than trying to apply the chamfer to a random bit of un-chamferable geometry". But a general solution is still impossible.).
  - TheSpiceIsLife 4y ago
    The chamfer applies to the first hole only, unless it is a copy of the first. Any changes to the first hole only apply to the first hole, unless that second hole is a linked copy of the first. ____ Is there an argument against this general solution?
    - jstanley 4y ago
      Who's to say which hole is the "first"?
      - mgdlbp 4y ago
        From the user's perspective, the circle that was originally drawn, which wasn't touched when adding a second circle to the sketch. If the original was deleted, then it's unclear (possibly assume the first replacement). IIRC (not testing now) FreeCAD already handles this example sensibly. You can add circles to the sketch and the chamfer stays put. If you delete the circle and add a new one, it appears on the new hole. But if you add a square instead, it moves to a random edge of the rectangular hole. The 'edge' of the rectangular hole is actually a loop of four edges, so this is understandable. Commercial software can fix some of these cases - I don't think the Freecad link branch can, but it does at least detect that the original geometry was deleted and raises an error asking you to reselect instead of allowing things to move around. And unrelated features downstream don't break. Not dissimilar UX to when I mess with something that Fusion can't handle, I say.
        phkahler 4y ago
        If the first is deleted then everything done to it afterward should be gone.
  - tohnjitor 4y ago
    It should gracefully fail and call for the hole feature to be redefined.