I’ve been using Rhino for a little over 2 years now and have come across a problem that I can’t solve for the life of me. A client sent over a large scale object that is meant to be 3D printed and it needs to be hollow on the interior to add lights to. I repaired the object to create a closed solid polysurface and then tried multiple pathways to get the hollowed effect. Once I can get a decent hollowing job I need to break the piece up into logical parts that fit on our printers so the piece can be assembled via the confines of my printing capacity.
Path 1-
I attempted to use the Shell command on this object with a target of 3/16” wall thickness. Regardless of my settings this always produced an object that was incomplete and came with the note ‘the new object is not solid’ (something along that line. The shelled object created multiple disjointed new surfaces and ultimately this path failed miserably for what I needed.
Path 2-
I took the closed polysurface and removed the bottom surface. I then converted that open polysurface into an open mesh. I then used the offset mesh command with the same target thickness of 3/16”. This seemed to be a win as it produced a ‘closed’ mesh. Unfortunately though it came with the side effect of hundreds of intersecting interior faces that I could not simply clean out without probably days of work. I tired to cheat the step afterwards by taking that mesh and inserting it into a slicing software. The software took the mesh and produced a model that was missing some faces on the exterior and some incredibly small and intersecting wall thicknesses that were unprintable.
I have read just about every topic in the forum from over the past decade discussing similar issues and everyone found somewhat of a resolution but all of those suggestions seemed to not work on my model. I’m hoping a Rhino genius here can help this simpleton.
I attached a file of the object I have been working with. Please let me know if there is anything else I can provide to assist in solving this puzzle.
This is all brilliant! Thank you so much, I spent all day looking for answers and never came across these videos. Can you share more of the exact steps you took on the castle? I just tried to run the shrink-wrap command on my program with the same object and Rhino crashed. How did you get the bottom removed so cleanly? Many thanks again, you’re incredible.
There are a number of pages of tutorials here that could help in the future. Here is a short page of reverse engineering tools: Rhino - Learn to use Rhino
shrinkwrap using the default edge length settings, it’ll be too coarse let it calculate and preview.
then half that setting, (so if the default is 1.5 units, half it to .75 and let it calculate)
continue to half the value until you are happy wit the result. Remember, you don’t need a ton of detail on the inside surfaces.
then add a negative value in the offset channel to the wall thickness you need. in your case -.1875”
accept the values and let the tool complete.
now isolate your resulting mesh, and ctrl+shift select the very bottom row of polygons and extrude them downwards to make the “plug” extend thru the bottom of the nurbs surfaces.
now using mesh booleans, subtract your resultant mesh from your original nurbs part, and you will get a mesh result.
this part should be watertight, verify with selopenmesh. It should not light up.
Ah ok! I got a good inset mesh made, I am on Mac and ctrl+shift doesn’t seem to have the same effect for me. The only way I know how to do something like that is by exploding the object and scaling out the section I need. I’m sure there an equal to what you are doing and what I can but trying to work that out now. The shrink-wrap command is amazing and I never thought to use it this way though.
Edit: I realize now it is cmd+shift however I don’t see it allowing me to select the subjects in the mesh without exploding the mesh first… Not sure if I am missing something.
