Here’s a bowl shape I just made:
It’s a closed Brep with a planar/flat top. I’d like to cap or fill in all of the triangular spaces at the top. The standard Cap object seems to do nothing, and there are so many edges I just couldn’t find a nice way to deal with them. Maybe some add-on package has a method that will work?
CapFails.gh (1.7 MB)
Cap only works for closing open polysurfaces
in rhino there is the command DeleteHole which seems to work pretty well once you MergeAllCoplanarySurfaces
But such command doesn’t exist in GH
If you have time to do it, I would consider different strategies for generating your geometry to avoid creating those holes in the first place. I’ve found it often better/easier/cleaner to think about how to create cleaner geometry from the start, as opposed to spending time cleaning messy geometry.
Also it will be a lot easier for people to help you if you provide more of your actual script instead of just the output.
That’s what I always do Nick - I learned that concept long ago when I discovered that anything other than a Closed Brep is likely to have obscure errors in the exported STL file. And in this case the whole reason the geometry I showed above exists is to get the results of the intersection of this:
with this:
TBH I haven’t been able to come up with any other way to create the final geometry - I tried Morph and SMorph but gave up on those because I kept getting weird results.
AHA! Thanks for that Maxime - I thought there should be some way to fix the holes, but had no idea what that might be.
To create geometry for 3D printing I only use GH - My only use of Rhino is to export STL files. (And yes, I know….)
I’ll do some research on how to use these 2 Rhino commands; hopefully it won’t take too long to get the final result I’m looking for. Heck, maybe this will motivate me enough to try writing a GH script that invokes them.
Thanks again for enlightening me.
Hi Birk,
Just a quick caution: if you look carefully at @M_Thorez’s illustration you will see that the entire holes disappear, including the “triangular” openings at the bottom. If you want to keep them to preserve the pattern, you need to wirecut the rim off the rest of the bowl and DeleteHole the rim part before unioning the top and bottom together again.
It’s the difference between this:
and this:
Also, one of the holes coincides with the seam of the bowl and if you attempt DeleteHole on that you will delete most of your model! For that one you have to extract and delete the internal vertical surfaces and use untrim on the edges of the resulting openings in top and outside faces.
It is possible to create a solid rim in Grasshopper. If I can tidy up my hackings enough not to be embarrassed by them, I’ll post a solution later.
Regards
Jeremy
This is directly related to the problem in this thread which you do not seem to understand. Solid Union is failing on co-planar surfaces and relates to curve seam. You can already see it in your image.
Gak! Actually Jeremy your post makes me think I’ll just settle for the holes as they are. For the past hour or so I’ve been trying to figure out how to do the Rhino DeleteHoles function using info I’ve found online. Of course nothing has worked - maybe because I have no working knowledge of Rhino (am I supposed to just naturally know I need to use Shift+Ctl to select a face?), but more likely because all the online info is more or less out of date.
Maybe that’s a good thing because I’d rather have the top edge holes than lose them along with the bottom ones - that fact just never occurred to me. (How did you do that anyway?)
FYI I do 3D printing as a hobby and post all my designs online for free. People get to decide for themselves if they want to make a print of one of my designs or not. So my only reason to remove the top edge surface holes was to make the top edge look like what one would expect. So who knows - maybe people will like the extra holes.
My primary objective was to see if I could make a usable bowl shape from the 2 pieces of geometry I showed above. I printed a small version last night, so I know what I’ve got now will produce a printable result or reasonable size.
Hi Volker - I’m not sure what you mean by the “it”, but I can tell you that I’ve printed 2 small trivets that came out just fine:
In general I’ve found that as long as I give my slicer an STL file made from a Closed Brep the resulting GCode will print OK. When I do run into a case where I can’t produce a Closed Brep it’s usually not too difficult to find some sort of mistake in the geometry creation process and fix it.
Last night I printed a small test of the object of this discussion and it came out OK, so the issue of the top edge holes is not a show stopper for me.
In fact you don’t even need to boolean union anything for 3D printing. You can export thousands of individual, overlapping meshes into a single *.stl and it prints just fine.
Each strut you see is a single mesh pipe… each color is a separate part.
What I am trying to explain, Birk, is that these curves:
should not exist after the solid union. There should only be the inner and outer perimeters and the curves of the enclosed holes. Either the input BReps are misaligned (which I don’t think is the case) or Solid Union is failing to union coplanar faces as it is known to do. This prevents you from successfully capturing the holes to work with, i.e. cap or whatever else it is that you want to do. That you have a closed BRep and the form prints is beside the point.
In this case, the simplest solution is to get the bounding box of the BRep, shift it down by a tenth of a millimeter, and Solid Intersect. I doubt anyone’s going to be crying about the lost height.
Pretty…
Hi Martin - yes, I know - I’ve often printed things without doing a final SUnion. But it is also true that sometimes, for reasons unknown to me, that doesn’t work, and I have to do something to get to a final Closed Brep.
“Doesn’t work” means my slicer (Orca) find open edges or mismatched corners or joints in Rhino’s STL file. Orca has a link to (I think) Microsoft’s fixer-upper for problems like that, but using that often fails with things like closing open areas or connecting things that shouldn’t be connected. So for simplicity’s sake I typically shoot for a Closed Brep, because those seem to always work OK.
PS: That bluish sphere is just spectacular - closest thing to Chihuly quality I’ve seen printed anywhere. Congrats.
FYI, this is how it would look from above with the holes capped at the top.
I think it will probably look better with the holes open - with a flat top the straight edges conflict with our expectation of smooth curves; without the holes they have lost their raison d’etre.
Gosh - I had no idea my original post would generate so much interest…
Thanks - your comment does explain a lot. I can tell you it certainly wasn’t known to me. But then I know almost nothing about Rhino - so I guess that one’s on me.
Now I understand why I couldn’t select any surface face from the Baked Closed Brep. So instead I tried your suggestion like this:
Which is I think what you suggested. The Cap didn’t close any holes I could detect, but that’s ok because I think this poor horse has been beat to death.
I think I might be able to make the problem disappear by slightly changing the size of the simple bowl shape that intersects with the extrusion. That’s a bit tedious to do but might just be the easiest solution.
OK - I give up. How did you do that? My first thought was you used a graphics editor to tweak my original image. But that doesn’t explain how you were able to create the upward looking side view.
Your image almost look like it’s ray-traced, which means you were somehow able to reconstruct the geometry, which isn’t anything simple. I know I miss some details by not knowing much about Rhino, but your images look like some sort of magic to me.
PS: I’m glad we agree that the open holes do look better.
Hi,
Concerning DeleteHole, have you applied MergeAllCoplanaryFaces to the upper first first?
then, the command itself asks you to select one of the edges of the hole to delete it. When I tried it on my computer it worked like a charm (see my screenshot)
Yes, I did do that - that’s how I found out you have to use Ctrl/Shift to select a face. But when I tried that all I got was the small cursor arrow, and when I pointed that at one of the top edge faces and clicked on it nothing happened at all. So I figured there was something else wrong.
