Join Dave Schultze for an in-depth discussion in this video Building a 3D gear, part of Rhino: Tips, Tricks & Techniques.
- [Instructor] In this part two lesson, we continue our gear demo from earlier. Remember, the key here is, as always, to explore strategies that can help us build stuff more efficiently. Let's zoom into the gear curve down below here on the construction plane. Notice we've got the 24 teeth that we built previously. We've got a lot of sharp edges. My goal here is to fillet all of them and this technique I call, pre-filletize because it's efficient and I like to make up words.
But this strategy actually saves us a ton of time later. If we waited to do the fillets after it was a solid, it'd be a lot of additional picking. So, you're pretty familiar with the fillet command, which we could do at any time. It's over here on the main toolbar, fillet curves, so imagine going around filleting each and every one of these little sharp edges. Instead of doing that, I'm going to introduce you to what I call a cousin command, which is a weird way to describe it but here's the thinking.
Instead of using the fillet curve, we're going to use his cousin, which has a similar name and is located right downstairs. Fillet Corners, you might have never noticed, but it'll find every single sharp edge and then put a fillet on it for you. Don't believe me? I'm going to right-click right now, I'm going to leave the five in there, or change it if you need to do that now, hit Enter, done. I just filleted about 100 edges in there, pretty cool. Let's make this gear a little more interesting before we go into 3D.
I've got the center axle hole in the middle. We've got this other little detail circle here but it's not very interesting. Let's make an array with more of these guys. So this is always fun and sometimes a little bit confusing for people when we do a circular array. This is on the Transform menu, under Array, Polar, not because it's chilly, but instead because it goes in a circular pattern, kind of like around the North Pole. So we give it a center, I'm just going to snap here.
The number of items, you can type in any number you want, I've decided eight works pretty good so we'll hit Enter right now. Now occasionally this number will not be 360, but typically that's always what you want. You can type in 180 or any degree you want to get them to spread on a partial circle. I typically always want to go all the way around. So make sure it's at 360 and then right-click. This is pretty cool, we get a little preview here, it's a little hard to see 'cause they're kind of very light shading here, kind of pink color. If that's okay, you can just right-click or hit Enter to accept.
If not, you can go ahead and change the number of items. A lot of times they will be too close or too far, so this is really handy. You don't have to keep stopping and starting with new numbers, you can just check them right now before you're done. This looks good to me, I'll hit Enter. Now we've got a series of curves on a flat plane, which is good for the extrusion. I'm going to go ahead and draw a box around all those guys, make sure you don't pick up any of the axis lines, which I have locked so it's not going to be a problem there.
Let's go up to the Solid menu, Extrude Planar Curve, Straight. Now a lot of times by default it won't have both sides on, so it's only going to go one way. Make sure you check that the both sides if you want to keep things kind of organized and symmetrical, this way it's kind of centered on the origin, which is a great way to do it. I'm going to go ahead and type in an exact number but you can always eyeball stuff. I'm going to use 10, so that actually makes it 20 units thick, why? We went 10 each way 'cause of the both sides command.
Okay let's take care of our secondary fillets. Going back in time to some of the other videos you might have watched, I always break fillets into two passes, big ones first, those are already done from the pre-filletize. Those were five around all those edges. So now when we do this top edge here, we need to be a smaller number, less than five. So that would be, two or three would be perfect. Sometimes you just want to go half the original value, just so it looks a little bit different, as opposed to being too close and a little bit too symmetrical for some people's tastes.
Let's go ahead and do the Solid menu here. We're going to go ahead and Fillet Edge, there's some other options here but we're just going to pick the first one. Now we can click, I do want to change the radius here, two I think is going to be fine. Now if you have a clean piece of geometry and you click, it should go all the way around. If not, you'll have little segments and you have to keep picking. I'm sure everyone's gone through this. When that happens just pick Chain Edges and that should send it zipping around, and that'll be the last thing you click.
It'll automatically go around until it hits back where it started. All those edges are picked. This worked fine so I didn't need to. I'm going to go ahead and right-click for the preview, right-click to accept, and that should take a little bit of a while. That's a lot of edges and radii to go ahead and put fillets on. Okay so let's talk about the third and final way to fillet edges. We talked about doing it one by one, which takes a lot of clicking. We mentioned the second way, which was chain edges. The third way is using selection boxes and this works really well from side views, or something besides perspective view.
So what I'm going to do here, is do the exact same command. By the way, you want to switch from one viewport to all four. You can double-click on any of the labels that'll go from whatever is selected to all four and back. Alright, so I'm going to right-click in this command line area. There was my Fillet Edge, it's a great way to repeat stuff. Now selecting edges, I'm not going to pick the edges one by one, I'm going to try to draw a box around that bottom face. Now it also picked the circles inside, so you may want to deselect some of those, or leave 'em as is.
But that's a great way to pick a lot of edges quickly. If you do want to deselect 'em, use Control and then select them in one of the other views, and this is why it's really handy to have perspective and then one of the other Ortho views open, so you can make sure you're picking what you think you pick. 'Cause right now if I only had the front view open, I would have no idea what was going to happen. I'm going to go ahead and just accept that, we'll right-click and then resume when it's complete. Okay our fillet is done, took about 20 seconds or so, it'll vary depending on the speed of your computer, and how many edges you picked obviously.
Let's go back to the perspective view here and wrap this up. So the strategies I shared here today work great to build things more efficiently and quickly, but that's only half the story. Remember by using curves, you also make it easier to explore other options and then revise designs when needed. If that happens, just throw away the 3D geometry, tweak a curve or two, and rebuild.
- 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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