Boolean for 3d print

Hi guys, I’m trying to make this file into one that can be 3D printed so I’m trying to join all of these polysurfaces into one closed one. I’ve tried trimming at all of the intersections and joining the naked edges but it’s taking me ages and the files getting so complex that rhino’s getting really slow. I thought Boolean union might save time but whenever I try to use it one of the polysurfaces being joined together just vanishes. Can anybody help with a reasonable quick way to do this? Thank you

Even saved small the file is 60MB unfortunately, but does anybody know if there are any usual problems with Boolean tools

Note that for 3D printing, generally it’s not required to have one single object. It depends on the slicer program if this is required.

At any rate, you could try to export a few of the object that you are having problems with and post that here. That will most likely be a much smaller file.

Given that you have written that your objects have naked edges…they are more than likely not closed polysurfaces.

For me a vanishing object after a boolean function is usually a sign that I tried to Boolean an open polysurface with a closed polysurface.

Pretty sure you need closed surfaces/polysurfaces for boolean functions to work properly.

Well, it helps in order for them to be predictable, but it is not required… If a complete intersection is found, you can use open objects for Boolean operations, but you need to know the surface normal directions of all elements in order to know in advance what parts will be kept and what will be thrown away. As you said, if you think the objects are closed but the operation removes parts you don’t expect, one or more of the objects involved are most likely open.

Open edges that run through the area where objects are to be trimmed with each other will cause Boolean operations to fail because the intersection curve will be open at that point. In V6, these areas may be marked with a dot containing an exclamation point.

@danjarvis8 One other way to attack the problem of a lot of badly-made objects that have open edges - if the destination is a 3D print - is simply to mesh them, then try with Rhino’s mesh repair tools and/or an external .stl repair software to fix/combine them into closed volume(s). It may be much faster. Some professional 3D printer driver packages have automatic fixing routines built-in.

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@Helvetosaur Thanks for the explanation Mitch. I have noticed sometimes I do get open objects (that I thought were closed) to Boolean…I turn the result to mesh to send to my 3D printer and it gets flagged as not suitable for an STL…because of being open with the naked edges.

Generally I fix the polysurfaces over trying to use the MeshRepair tool. I use it but not that often.


Thanks guys I’ll try both and see what works. I’m trying to repair the polysurfaces at the moment but it’s taking me forever so meshing might be the way to go

Another question to ask here is why are they are needing repair in the first place… how did they get that way? It’s always better to make things correctly in the first place to avoid having to fix stuff “downstream”.

I’ve made a steel roof grid mainly constructed from polysurfaces made from sweep tools. I’ve just found out this means there’s a ton of naked edges

Not necessarily if you take some care. If the profiles are closed planar curves, the sweeps will have open planar ends, all you need to do is use Cap to close the ends. Now, if you have several sweeps coming together at different angles at a truss joint, that will most like cause difficulties in getting a good intersection - as 3D trusses also do in real life.

There are some solutions that might work OK for this for 3D printing as well - one of them that I use is creating spheres at the joints that are just big enough to enclose all the horrible crazy intersections at each joint. If each leg of the truss coming into the joint meets the sphere surface before it meets another leg, the whole thing will easily Boolean into a solid. The spheres might or might not be very visible in the final printed object, depending on the size and the resolution of the printer.

That sounds like a good idea, I’d forgotten about all the additional structure the printer has to put into the model so it can be printed as well, although I think the printer resolution is quite good

I think where I’d been going wrong in my model is that for some bizarre reason I forgot cap was there so I’ve been duplicating borders and then using srf from planar crv. I just happened to forget that control existed on a nightmare of a model

I’ve split the model into 4 so this uploads, I think it’s almost there but now I’m just having problems with Boolean unioning all the polysurfaces. There are quite a lot of join edges in this model which could be a problem but on a lot of the polysurfaces if I explode, rebuild the edges and join I get the same result. Could anybody help with thisrf print 1 tol.3dm (15.1 MB)

Don’t worry I thin the sphere fix will help

well, the model is pretty messy, first of all, you have some bad surfaces, second is very far from the origin and last but not least, several objects have self-intersecting surfaces, you need to solve those corners on each sweep to get the booleans to work.

One of the self-intersection examples:

Ok, could I solve that by getting a dupborder of the problematic sweeps, editing a little and then use that as a sweep rail?