It is nice wh e you can Boolean all objects into a nice single clean mesh but many times the programs can become unstable or not be able to complete the function depending on system memory, complexity of the geometry and of course the random bug tha only happens on rush jobs.
There is no reason why the slicing software shouldn’t be able to remove internal hollows.
Calculating the intersection of many randomly oriented polygons is a non-trivial task. And once the intersections are determined, the existing geometry has to be modified to eliminate overlapping regions. So I’m thinking there are probably lots of reasons why slicing software shouldn’t be able to remove internal overlaps. Many of the same reasons I’d wager that cause your CAD software to crash when doing CSG (CSG Union is the same mathematical exercise as detecting and eliminating overlapping 3D regions).
IMO if your CAD software is crashing doing CSG, that’s a problem you can and should fix. What are you using for CAD?
I will bet my money on the hunch that KenCitron is using Blender.
That’s what I use and it often crashes with boolean operations. I have a love/hate relationship with the program.
I’ve used MeshMixer with a certain degree of sucess. It doesn’t usually crash on Boolean operations, but it doesn’t always find a solution depending on the complexity of the objects.
I’m not sure about other programs, but MeshMixer can’t Boolean multiple objects, just 2 at a time, so if you have many overlapping objects, you have to do them one by one,.
3ds Max has problems with Booleans too, though most of the time it works as long as the meshes are OK in the first place.
I use Lightwave3D for simpler tasks. Like 3DS, it sometimes has problems but more often than not it’s caused by an error in one of the polygon sets. 1 and 2 vertice polys and stray points or degenerate polys tend to cause problems. These are due to mistakes I’ve made in modeling something, or by previous CSG operations I didn’t clean up properly. I find them and fix them as best as I can. Rarely I run into something I can’t make work (or is too much work to make work). I can usually solve those issues by making slight adjustments to the geometry in the overlapped regions. If it changes a critical external dimension, I fix it after the CSG is done. I still end up with non-manifold edges every once in awhile, but NetFabb generally takes care of these so I don’t have to go hunt them down in the source geometry and fix it there… It’s worth the effort of finding a way to get CSG to work, getting the geometry to be as clean as you can get it. Workarounds can cause their own problems. In my experience, they are worth avoiding…
I don’t use Blender because it is just a poly modeler and not suitable for cad work. I use MOI3d and so far for the many years I have been using it MOI has NEVER crashed. It doesn’t matter what program your using since if the object is too complex the Boolean operation will fail at some point due to system resources or it may take more than a lifetime to calculate. Another downside to permanent Booleans is they typically can’t undone unless you happen to have an expensive parametric modeler which most don’t. Having version after version of models is not a great answer either.
What I have found so far that the OBJ format seems to come in cleaner into PreForm vrs STL when there are multiple mesh groups involved. PreForm seems to be able to repair the files much better even when the overlaps are extreme. I believe this is because it is able to see the objects as separate objects and not as one continuous mesh with holes such as the case with stl format.
Not sure if this was a fix since the last update but regardless, if your print requires overlaps use the obj format for import. This for me is a HUGE time saver!
Thanks
Modo has a pretty great booleans tool. still I have to say in my experience I’ve never had any issues or artifacts with overlapping pieces, otherwise none of my parts would turn out well because they all do that.
For now MOI is only a 32 bit app, there is a 64 bit version coming out. I really don’t have any problems with MOI and it is a rock solid dependable direct nurbs modeler.
It does seem that both the obj and stl import issues with overlapping objects has been resolved. I really thank the Formlabs team for this. Now the auto repair generates nice clean slices where objects intersect.
I think if i were to change modelers I would look at a parametric modeler such as Xenon but for the most part, MOI is just too simple and efficient to use.
There is a misconception that Blender is just a poly modeller, but you can create highly complex parametric geometry via their modifiers, nurbs, or straight Python programming, and you can make organic shapes that have no visible faceting. That’s in real life, not just normal screen smoothing used for rendering.
You just need to apply the parametrized functions that describe the model at the time of export.
All modelling software has to convert the geometry to polygons before it can be printed on an SLA machine
It is free, and you can do many things that others can’t do if you wanted to do more than 3D printing. It also has a steep learning curve and plenty of bugs.
I am also using Blender for CAD, as I am building a Robot Drummer, but it is really designed for artists. I would prefer to use a more technical program for this, but good CAD software was usually too expensive to justify the purchase for the extra benefits. MOI is cheap enough so I have downloaded a trial version to check it out.
I didn’t know Blender had nurb capabilities. The main reason I don’t use Blender is because from the little I did try it I found that between versions, plug-ins may or may not be compatible. The other reason is I found it to be shortcut key heavy with an extremely clunky un-traditional interface. For many many years I had used Amapi and eventually Amapi pro until the programming team had been broken up when it was sold off. Some of those users had been using Rhino and many others jumped to MOI written by the guy that wrote Rhino.
MOI is a direct modeler and has a very limited dynamic functions ie you an modify a profile of an extrusion, depth or revolve profile post creation but once other functions are applied such as a chamfer or Boolean then your married to that shape.
What MOI doe offer is the ability to easily dissociate surfaces, trim them and stitch them back together so making complex shapes is possible but some forms may just take longer to do but the low level editing of nurb forms is extremely easy.
You are correct about 3d printers needing polygonal geometry to process but it is nice to be able to control that post creation of the objects on export rather than trying to work with millions of polygons at one time. MOI has a really nice exporter that allows you great control of the faceting of shapes based on edge length, curvature and restrictions on minimum feature size making the stl or obj as efficient as possible. You will see that when you do a save as and choose advanced options.
For myself I have run MOI on all sorts of machines from a 1.4gz Celeron laptop to a dual chip Xeon workstation and it runs equally well and stable. I have never had it crash on me nor ever lose a file. That just amazes me. MOI will always allow you to esc function that takes too long and it will at worst tell you there is a calculation error but not toss you back to the desktop or eat your work.
You may want to check some of the external scripts found in the forums and if you have questions just email Michael.
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