Join Dave Schultze for an in-depth discussion in this video Prototyping part 7: Exporting for 3D printing, part of Rhino: Tips, Tricks & Techniques.
- [Instructor] In our final prototyping lesson, we export our closed Rhino model for 3D printing. However, I've developed one extra step in the process that makes it virtually guaranteed your file will be perfectly printable. Little background first: when you go outside to a 3D print, you're going to be making a mesh and then saving that as an STL file format. This is different than the NURBS you're familiar with. This is easy to change and modify and edit. The mesh is pretty much the end of the line, used just for printing.
You'd never want to edit this guy. I'll give you an example if you don't believe me. We're going to zoom in here, and I'm going to turn the control points on; you can do this button called Points On, or F10 for the shortcut, PC only. These points are so closely spaced, if I were to move one out, you could see why you don't even want to try. Let's Control Z to get that guy back in there, and then right click on that same button to turn the control points off. Just want you to understand what an STL file format is working with, and it's basically just a mesh; a series of straight edges all connected together at the intersections.
I did say I have an extra step to guarantee the quality of this, and make things go smoother. Instead, I'm just going to show you how people used to do it, and how problems can occur. As long as this model is closed, which I know by verifying over here on the properties ... In the past, I would've just gone File, Export Selected, and then select the STL file format. The problem with this is there may be a glitch or error cropping up, even though this NURBS model is closed.
It's entirely possible that you'd get something opening up in your mesh, and since it's outside, you never notice it. I'm going to show you one extra step where we get to create the mesh, and then inspect it before we export out to STL. Here we go; we're going to select on the NURBS object, and this extra step is right here under Mesh from NURBS. You can preview this. If you ever run into glitches where you're not happy, you can come in here and kind of dial in some of these numbers a little bit; I typically leave the default as-is.
Let's go back to Simple Controls, and somewhere in the three-quarter range usually works the best. Let's take a preview to demonstrate, and there is the conversion to the polygons, or the straight edges. People always ask, "Should I crank it up to the top?" Well, a lot of times, you're generating more detail than your printer can capture, but that's fine; these mesh files are not that big. So we'll just leave it at the top. Just for fun, I like to show the range of exporting resolutions here by previewing it very low.
Now you can see it's the large, faceted edges that would definitely look pretty bad. Back up to the top, hit Okay. Now, the mesh will appear right on top of your model. It may be a little bit confusing, but if you click on the surface, you will see you have the poly-surface, or NURBS, and there's the mesh. If it bothers you, you can move that off to the side and then inspect it closely. I'll do this quick inspection to see if there's any gaps or openings.
Usually, it's just fine, and we can do our double check the same way we checked the NURBS by just selecting it, going over to Properties, and making sure it's still closed. If it's not closed, the quickest way to proceed is just throw this mesh away; just select it, hit Delete, then go back and create a new mesh, and just change the slider a little bit. Almost every time I've had an issue, that fixes it. There's probably some resolution error in a very tight spot that I'm not seeing.
If you're not sure where the error is occurring, you can select this and you can use the same tool we've used before; Analyze, Edge Tools, Show Edges. This has no naked edges, but they would light up just like it's a NURBS model from before. That will help you focus your repair efforts; again, you just want to find out where the problem is, it's probably in a seam or a tight spot. Let's go ahead and close this. You would delete the mesh, go back and fix or repair or clean up the NURBS model, and then just make one more mesh.
However, ours is perfectly fine, so we're ready to export. We'll go back to where we were earlier, right before I got into this extra step; so we're going to Export Selected, we're going to pick the STL file format. It's kind of down here; you'll have to scroll down, but it's in there: STL, stereolithography. Hit Save. I'm going to cancel out of this because we don't need to do it. That STL file, that separate file, is what you send to the printer, whether it's in your office or someone outside; a third party.
That's the universal file format; you're looking to send them an STL export from one of these mesh. I want to show you what the output looks like. I'm using a printer; it's called a Zortrax brand. This is a process called FDM. You can see there's a little injector at the top; it heats up the filament, and it squirts it out layer-by-layer. What you're seeing over here is supports, and these typically break off fairly easily; occasionally you'll need to do a little bit of extra sanding.
It's a high enough quality printer where it was just fine after I snapped the supports off by hand. It's nice not to have any extra tools, or have to sand too much. You might notice I've got the glasses off to the side; there was a lot of tight little gaps and intersections between the glasses and the head. So, I just separate parts whenever possible. You will have to do that if your model is bigger then the printer; you may have to break it up and do multiple parts and then glue it back together. Here's the final, and like I said, I have not done any sanding; if you get a good quality printer, it should look pretty nice.
This guy's about four inches tall, and I used the exact same file you've seen in all these prior video demos. This process of creating the mesh first inside of Rhino, which only adds one extra step and gives you an opportunity to double check, is simple and fast. I always use this process to be 100% sure before I 3D print or send it out. Keep in mind: outside printing companies cannot be counted on to catch mistakes or fix anything. Even worse, you can lose a couple of days just to find out they won't print it; then you need to fix it anyway.
Follow my steps, and you will have one less thing to worry about.
- Building and detailing a space helmet
- Making a flexible duct
- Building details on round pipes
- Modeling organic objects
- Using the SrfSeam command to move seams out of your way
Skill Level Intermediate
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