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I would be so happy if Blender tackled parametric modeling like this. Tried FreeCAD, gave up in frustration after I drew a second sketch on the face of an obje

I would be so happy if Blender tackled parametric modeling like this. Tried FreeCAD, gave up in frustration after I drew a second sketch on the face of an object and no matter what I did it wouldn't extrude. After that went poorly I'd just picked up Fusion 360 about a month ago and have been doing pretty well with that. Whoops.

splatcollision 6y ago
Since blender is so easy to write add-ons for with their Python API, I'd be surprised if there wasn't already community effort around this. I don't know much about CAD requirements, but it looks like there are a few tools available already and efforts underway: https://duckduckgo.com/?q=blender+cad+add-on https://duckduckgo.com/?q=blender+cad+add-on
- wlesieutre 6y ago
  The critical thing is that Fusion 360 and similar tools use a non-destructive parametric workflow. Everything is defined based on sketches with dimensions and constraints like "this angle is 30 degrees, these lines are parallel, this is a right angle, this radius is 3 cm" and you can go back in at any point to change a previous dimension, even if it was on the very first shape you started building from. The whole object recalculates from the new design. The CAD addons for blender are helpful for doing some more precise drawing actions (like finding the intersection point of two edges, which blender doesn't normally give you), but they're still fundamentally in a destructive mesh workflow. You have a pile of vertices/edges/faces, you do some editing, and you have a different pile of verticies/edges/faces. There's some stuff doable with non-destructive modifiers, but they're for very limited specific tasks.
  - skykooler 6y ago
    I think that with a bit of work, an addon could build on the boolean modifiers (among others) and create something fairly powerful.
samwillis 6y ago
The trouble is that Blender is fundamentally the wrong platform to build a parametric (solid body) modeller on. Everything in blender is a mesh, whereas in a parametric solid body modeller everything is a BREP[0]. It would ether need a new BREP kernel or to include an existing open source BREP kernel, the most advanced being OpenCASCADE which FreeCAD is built upon. Would love to be proved wrong though! 0: https://en.wikipedia.org/wiki/Boundary_representation https://en.wikipedia.org/wiki/Boundary_representation 1: https://www.opencascade.com https://www.opencascade.com
- wlesieutre 6y ago
  Blender is mostly meshes, but it can already have other geometry types like NURBS. You can convert a nurbs object to a mesh, but the modeling process and data format is totally different. I'm imagining that the solid modeling system would be a separate mode type like that.
  - eloisant 6y ago
    Still, blender is not a CAD tool. It's great to great organic designs (characters, animals, figurines, etc.) but it's not good for functional parts. And it will never be, CAD and 3D modeling for organic/art are fundamentally different.
    - KMnO4 6y ago
      I wonder how much work it would be to turn it into a proper CAD tool. I would donate a significant chunk of my paycheck to Blender if it supported parametric CAD. Obviously that would be pocket change to the Blender Foundation, but if enough people did then maybe it would be worth it. I'd wager there a fairly big group of people like me who need somewhat decent CAD for hobby use. And if those who can afford to pay put that money towards Blender, we could make it better overall for those who can't.
      - UncleEntity 6y ago
        > I wonder how much work it would be to turn it into a proper CAD tool. Never used it myself but there are some CAD tool addons you can try -- also they seem to have incorporated some 'hard modeling' features which, I would imagine, aren't that far from the CADiverse. Also, unless they worked on it (semi)recently, the NURBS in blender is a bit of a trainwreck which everyone was scared to even look in its direction.
triclops200 6y ago
I went through the same exact issue with FreeCAD and eventually ended up using http://solvespace.com/index.pl http://solvespace.com/index.pl It's FOSS and works really well. Isn't as fully featured as Fusion360, but I personally love its interface
- wlesieutre 6y ago
  I just found that linked in r/3dprinting last night on a discussion about the Autodesk's new Fusion 360 bullshit, it's on my list to try out! If SolveSpace doesn't pan out for me I'll try OpenSCAD next, but I gather there are some issues with that modeling approach where fillets/chamfers are much more challenging to create than they are in a graphical modeller.
  - Kliment 6y ago
    With OpenSCAD, you don't have fillets as part of the language, but you can do chamfers or machinable parts easily using the minkowski sum operation, which basically places an object of your choice on every point along the surface of another object. I've used this to do insets and outsets, radiused corners, and all sorts of other funky stuff. However, if you want that sort of operations you would probably be better off with cadquery, which is basically the engine behind FreeCAD, with a really powerful Python interface. It has native support for face operations like fillets.
    - dividedbyzero 6y ago
      No idea if I'm doing something wrong, but minkowski operations seem to cause OpenSCAD's preview and rendering to become extremely slow real quick, on the order of minutes for models with several such parts.
      - Kliment 6y ago
        minkowski and hull operate on every vertex in your object mesh - this means they need to a) convert the solid into a mesh and b) do math for every combination of vertices in said mesh. That's O(n^2) operations for objects of complexity n. This means that they are much slower than csg operations (that operate on the underlying geometry rather than the mesh). They are definitely the slowest (but most powerful) operators in OpenSCAD. If you're doing something like minkowski-adding a sphere to a complex shape, use $fn=(some low number) on the sphere to reduce face count and speed things up initially while you're hacking around, then increase it again before final render.
bondarchuk 6y ago
I know of Sverchok, a Blender plugin to do parametric modeling based on nodes/dataflow/visual programming (if you know what I mean). http://nikitron.cc.ua/sverchok_en.html http://nikitron.cc.ua/sverchok_en.html https://github.com/nortikin/sverchok https://github.com/nortikin/sverchok
- wlesieutre 6y ago
  Interesting, it doesn't look particularly geared toward mechanical parts, but I'll have to check this out!
AJ007 6y ago
My expectation is as companies like Adobe, Autodesk, et al become more bloated in their cloud pricing two things will happen: a) First, nuking the hobbyist/amateur users asphyxiates your future pipeline. These people will now use and invest their time in open source alternatives. Free open source alternatives that have downsides, over time will no longer have downsides. b) Your big corporate customers will independently finance the development of those open source platforms. As someone who first used Blender when it was a year or two old, and then didn't look at it again until 2.8: wow, they have done a damn good job. It isn't Maya or Modo, and misses some unique use cases, but it is amazingly easy to use. Learning curve from start to working animated model in game engine was hours not days. If Blender is any indication, the open source software tools are on a trajectory to be a lot better than the commercial stuff given enough time and focus.

splatcollision 6y ago

Since blender is so easy to write add-ons for with their Python API, I'd be surprised if there wasn't already community effort around this. I don't know much about CAD requirements, but it looks like there are a few tools available already and efforts underway: https://duckduckgo.com/?q=blender+cad+add-on https://duckduckgo.com/?q=blender+cad+add-on

wlesieutre 6y ago
The critical thing is that Fusion 360 and similar tools use a non-destructive parametric workflow. Everything is defined based on sketches with dimensions and constraints like "this angle is 30 degrees, these lines are parallel, this is a right angle, this radius is 3 cm" and you can go back in at any point to change a previous dimension, even if it was on the very first shape you started building from. The whole object recalculates from the new design. The CAD addons for blender are helpful for doing some more precise drawing actions (like finding the intersection point of two edges, which blender doesn't normally give you), but they're still fundamentally in a destructive mesh workflow. You have a pile of vertices/edges/faces, you do some editing, and you have a different pile of verticies/edges/faces. There's some stuff doable with non-destructive modifiers, but they're for very limited specific tasks.
- skykooler 6y ago
  I think that with a bit of work, an addon could build on the boolean modifiers (among others) and create something fairly powerful.

samwillis 6y ago

The trouble is that Blender is fundamentally the wrong platform to build a parametric (solid body) modeller on. Everything in blender is a mesh, whereas in a parametric solid body modeller everything is a BREP[0]. It would ether need a new BREP kernel or to include an existing open source BREP kernel, the most advanced being OpenCASCADE which FreeCAD is built upon. Would love to be proved wrong though! 0: https://en.wikipedia.org/wiki/Boundary_representation https://en.wikipedia.org/wiki/Boundary_representation 1: https://www.opencascade.com https://www.opencascade.com

wlesieutre 6y ago
Blender is mostly meshes, but it can already have other geometry types like NURBS. You can convert a nurbs object to a mesh, but the modeling process and data format is totally different. I'm imagining that the solid modeling system would be a separate mode type like that.
- eloisant 6y ago
  Still, blender is not a CAD tool. It's great to great organic designs (characters, animals, figurines, etc.) but it's not good for functional parts. And it will never be, CAD and 3D modeling for organic/art are fundamentally different.
  - KMnO4 6y ago
    I wonder how much work it would be to turn it into a proper CAD tool. I would donate a significant chunk of my paycheck to Blender if it supported parametric CAD. Obviously that would be pocket change to the Blender Foundation, but if enough people did then maybe it would be worth it. I'd wager there a fairly big group of people like me who need somewhat decent CAD for hobby use. And if those who can afford to pay put that money towards Blender, we could make it better overall for those who can't.
    - UncleEntity 6y ago
      > I wonder how much work it would be to turn it into a proper CAD tool. Never used it myself but there are some CAD tool addons you can try -- also they seem to have incorporated some 'hard modeling' features which, I would imagine, aren't that far from the CADiverse. Also, unless they worked on it (semi)recently, the NURBS in blender is a bit of a trainwreck which everyone was scared to even look in its direction.

triclops200 6y ago

I went through the same exact issue with FreeCAD and eventually ended up using http://solvespace.com/index.pl http://solvespace.com/index.pl It's FOSS and works really well. Isn't as fully featured as Fusion360, but I personally love its interface

wlesieutre 6y ago
I just found that linked in r/3dprinting last night on a discussion about the Autodesk's new Fusion 360 bullshit, it's on my list to try out! If SolveSpace doesn't pan out for me I'll try OpenSCAD next, but I gather there are some issues with that modeling approach where fillets/chamfers are much more challenging to create than they are in a graphical modeller.
- Kliment 6y ago
  With OpenSCAD, you don't have fillets as part of the language, but you can do chamfers or machinable parts easily using the minkowski sum operation, which basically places an object of your choice on every point along the surface of another object. I've used this to do insets and outsets, radiused corners, and all sorts of other funky stuff. However, if you want that sort of operations you would probably be better off with cadquery, which is basically the engine behind FreeCAD, with a really powerful Python interface. It has native support for face operations like fillets.
  - dividedbyzero 6y ago
    No idea if I'm doing something wrong, but minkowski operations seem to cause OpenSCAD's preview and rendering to become extremely slow real quick, on the order of minutes for models with several such parts.
    - Kliment 6y ago
      minkowski and hull operate on every vertex in your object mesh - this means they need to a) convert the solid into a mesh and b) do math for every combination of vertices in said mesh. That's O(n^2) operations for objects of complexity n. This means that they are much slower than csg operations (that operate on the underlying geometry rather than the mesh). They are definitely the slowest (but most powerful) operators in OpenSCAD. If you're doing something like minkowski-adding a sphere to a complex shape, use $fn=(some low number) on the sphere to reduce face count and speed things up initially while you're hacking around, then increase it again before final render.

bondarchuk 6y ago

I know of Sverchok, a Blender plugin to do parametric modeling based on nodes/dataflow/visual programming (if you know what I mean). http://nikitron.cc.ua/sverchok_en.html http://nikitron.cc.ua/sverchok_en.html https://github.com/nortikin/sverchok https://github.com/nortikin/sverchok

wlesieutre 6y ago
Interesting, it doesn't look particularly geared toward mechanical parts, but I'll have to check this out!

AJ007 6y ago

My expectation is as companies like Adobe, Autodesk, et al become more bloated in their cloud pricing two things will happen: a) First, nuking the hobbyist/amateur users asphyxiates your future pipeline. These people will now use and invest their time in open source alternatives. Free open source alternatives that have downsides, over time will no longer have downsides. b) Your big corporate customers will independently finance the development of those open source platforms. As someone who first used Blender when it was a year or two old, and then didn't look at it again until 2.8: wow, they have done a damn good job. It isn't Maya or Modo, and misses some unique use cases, but it is amazingly easy to use. Learning curve from start to working animated model in game engine was hours not days. If Blender is any indication, the open source software tools are on a trajectory to be a lot better than the commercial stuff given enough time and focus.