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In this video, we are hopefully 100% complete with our design and modeling work, and ready to export for prototyping. Now, a prototype is a three-dimensional printout, which is to say a physical and real-world part you can hold in your hand. The prototype is typically fabricated with a high-tech machine, which uses your 3D data exported from Rhino. As soon as you've built your model carefully, cleanly and accurately, you might be the one person who never needs these strategies. But for everyone else, I've developed a series of quality checks and fixes that can make this somewhat stressful stage much easier.
Now as a reminder, the key for any prototyping process is to export a closed solid. We're going to focus on the arms. I'm going to turn off the robot layer. I zoom in here, and upon first glance, it looks closed, complete and finished, but that's actually no guarantee. So, let's try a quick check of the volume, which will tell us right off the bat if there is any openings anywhere on this model. I'm going to Analyze > Mass Properties > Volume. Select the entire arm, right-click, and unfortunately, this is telling me that it's not closed, because otherwise it would just give me a number of the volume.
So, let's just go OK, and it will give you an estimate. It'll try to assume that if there is a tiny opening, it's closed there and give you a rough volume measurement. We can see that up here in the command line. Let's do a quick inspection. Oh! I see one problem right off the bat. We've got an opening here on this shoulder pin. Okay, pretty easy to fix that, assuming this is a flat plane, which it looks like since that was probably an extrusion. Let's go to Surface menu and one of my favorite commands, Planar Curves.
Whether or not there is a curve there, we can use the edge, so I'm just going to select it, right-click to accept and we've attached the surface there. The next step is just to join it. This is as simple as picking the new surface, the rest of the model and just doing the little puzzle piece here. That's the Join or Ctrl+J would be the shortcut. Okay, now you can also check on the Status Line, instead of running that command again, and it says it's still an open polysurface. So, that's another little tip that you might need to continue working.
So, I'm not going to do the Volume this time. I'm going to try another advanced command, which will tell us exactly where the problem might be. So, we find this command under the Surface menu. It's under the Edge Tools, and we're going to Show all edges. So, I'm going to pick this object, Enter. Now it looks like everything is lighting up, but that's because the default typically is to show all the edges. That's kind of where we'd expect them to be. However, we're concerned about naked edges, and that just means edges that are not joined.
So, when I switch over to there and also check the command line, we notice that 188 of those edges are gone. We turn that off, and only two naked edges remain. So, that is pretty good news. We always hope for zero, but two is pretty low. Here is a problem right off the bat. We can see that this surface or actually polysurface wasn't joined to the polysurface next to it. I can close that. That's another simple operation. I'm going to select the two polysurfaces. Ctrl+J to Join.
Now, it says it's still one open polysurface. We've got some more edges to go check out. Hopefully, we're getting close. Let's repeat the Surface > Edge Tools > Show Edges. Select the object, and there is the interesting situation. I'm going to go ahead and zoom in here a bit. I select that surface and then do Zoom Selected. This is a common problem. We have a gap there. It looks like it's joined on three quarters of the circle here.
It's just somehow peeled apart, probably because we've got a little bit sloppy, or didn't notice that. So, we definitely have to close that up. Fortunately, there is a command exactly for just such situations, and it's on the same menu, Surface > Edge tools > Join 2 Naked Edges. I'm going to select these two edges on opposite sides and this feedback will tell you hey, they are about 0.04 units apart. That's just in case that they are a lot farther apart, then you feel comfortable with your tolerance.
In those situations, you don't want to go ahead and join it. You might want to just remove one of the surfaces and rebuild it much cleaner. I'm going to go ahead and say Yes. So, it looks like those two edges are now merged together. Let me go back to our Volume check here. We can close this. Select the object, Analyze > Mass Properties > Volume. Bingo! We have a number. We have no warning, essentially saying to us that it's a one completely closed polysurface, otherwise known as a solid and ready for export.
So, there are a few basic strategies to verify. You have a closed solid, find openings, and finally, join or close them together. Of course, these are problems that can be eliminated 99.9% of the time by building clean curves using Osnaps to make sure they connect and then generating clean surfaces from those clean curves.
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