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In Rhino 4.0 Essential Training, author Dave Schultze shows how the 3D NURBS-based modeling tools in Rhino 4.0 are used to engineer products from toy robots to full-sized aircraft. This course concentrates on using Rhino 4.0 for industrial design and rapid prototyping, with a review of common 3D terminology using specific examples. Along with a comprehensive exploration of the Rhino interface, the course includes an introduction to building 3D objects with Rhino's three primary entities: the curve, the surface, and the solid. Exercise files are included with the course.
In this video, we will investigate the Rail Sweep commands: the One Rail and the Two Rail Sweeps. Both kind of sweeps can create surfaces that are either mechanical or organic. Mechanical surfaces have sharp edges and flat surfaces, while organic surfaces are very smooth and flowing. So, we'll take a look at both kinds of surfaces for each of the Rail commands. Since our robot is mostly mechanical, we'll take a little short detour and demo some of the sweeps that are organic. Let me maximize this Perspective window, turn on some organic lines, and let's check out, first of all, the One Rail Sweep.
I'm going to use this curve as the rail and the other curve as the profile. We find it underneath Surface menu > Sweep 1 Rail. Let's select the rail and then the curve, right-click to enter, hit OK. We'll take a look, so it's a pretty organic shape from two simple curves, but you know that the shape is somewhat limited because it has to follow that 1 Rail.
So, it's almost like the second edge along the top is an exact duplicate of the one below. So, to avoid that situation, there is the Two Rail Sweep, where each of the rails could be completely different, and I didn't mentioned before - we can have multiple profiles along there, that are also of different shapes. Let's start the Two Rail Sweep under the Surface menu, select the rails, then the Profiles. Hit Enter.
I'm going to take a look here. So, it's a much more organic shape, with a lot more power and control involved. However, if you think that this is going to be a little too complicated, judging by the isoparms on the surface, we can go ahead and say make is Simple, and then hit the Preview. Notice those isocurves are far fewer. So, what's happening is that it's following the constraints of the Rails and the Profile curves, but kind of simplifying and averaging the surface in between.
So, if it looks petty close, as I've mentioned before, Simpler is always better. Okay, now on to the Mechanical Sweeps. We are going to start off by working on the antenna. I just got a memo from the antenna department that our prior design was not passing the tests. So, they've had to take this enclosure and raise it up vertically. We're going to have to make up the difference with this profile here. Now for lot of zooming and panning sometimes you'll need to reset. So, the way to do that is select an object and go to Zoom Selected.
That will bring it back and recalibrate everything, okay. We've also mentioned before that we can use an edge, wherever it appears, as if it's a curve. So, let's start the command and see how that works. Surface > Sweep 1 Rail. I'm going to select this edge and in this cross section, hit Enter. It's pretty straightforward. There's not too many options. I'm going to go ahead and hit OK. And we'll kind of zoom around here and make sure it worked all right. This is another reason I like to work in the Perspective Viewport.
So, it looks like it went around nice and clean, and there is no twisting or pinching that can sometimes happen. You will also note, if I select this surface, it goes through. So, that's another technique I practice. You can always trim things back. I don't try to make it exact the first time. So, you'll notice that goes way inside, very easy to trim. We'll worry about that later. Next up: we have the Claw. This will be built in the center just to make it easy, and once this shape is complete, we'll move it over to one of the sides for the hand and then mirror the other copy.
Now I got another memo. It looks like these washers, or caps were on sale, so they have bought quite a few. I'm going to have to use those to build this next piece of geometry. So, let me go back to the four Viewports. We can talk about this shape here. Turn the control points on with F10. If we zoom in, you can see how that was constructed. Notice anytime two control points or more are close together that's an area of higher detail. Farther part tends to be smoother. So, that was drawn from the Right viewport, and if you look to the Front viewport, we just made a slight rotation of it because you can tell it has an angle, and then it mirrored the other side.
Turn of the Control point with F11. We're going to go back to the Perspective and maximize it. And we'll start off with the simplest shape here. There is a straight line. I'm going to use that just to see how it looks. Surface > Sweep 2 Rails. We've got these two profiles here, a Cross Section curve there, Enter, just say OK and we'll take a look here. So, it's a pretty involved surface. We could also cap that closed with another command, but I'm going to save that for the next step here.
I'm going to get rid of this, hit Delete. Direct your attention to these curves, top and bottom. So, I've talked about this before, but it's worth mentioning. This is what is called the Prefilletize. I've added some corner radius already built in. So, that adds some detail right, off the bat. We don't have to go back later and fill its surfaces or solids. Another way look at it is we have a kind of backup plan, if it doesn't look the way we intend.
So, I'm going to repeat the Surface > Sweep 2 Rails, then I'm going to pick both of these cross section curves. Starting and ending just to gain a little more control, hit OK, and let's take a look - so, a much more sweet-looking shape here. Now I talked about Capping that. So, let me show you what I recommend on this. We have an edge and a curve both, right along there, and it defines a flat plane.
So, we've visited this command before. Let's pay one more visit, Surface > from Planar Curves. So, I'm going to select this edge here, closing edge there, hit Enter. So, you can tell, as we've discussed before, we've got isocurves, one each going in each direction, meaning the surfaces as simple and clean as possible. Okay. We'll save the other side for later.
I'm going to do one more Two Rail Sweep, using the same technique where we can use an edge in place of a curve. Surface > Sweep 2 Rails, so here is the first rail or edge, second and then the cross section curve is basically these several segments and arcs connected together. Hit Enter. I answer OK and then zoom back. So, that's an excellent way to close off forms and use geometry that was given to you by others, or there are constraints that you need to work by.
So, as you can see, the one and two rail sweeps can do quite a bit. Remember, even if you are building mechanical geometry, you still want to keep all of the curves involved as simple as possible. Also, keep in mind that you can always add extra profiles if the surface is not generating as expected.
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