Here you learn to model the sprockets with the REVOLVE, EXTRUDE, FILLETEDGE, and ARRAY commands.
- [Instructor] Now that we have the sketches configured, we can begin modeling the sprockets. Right now this is on layer sprockets. So let's create a new corresponding 3D layer. I'll select this layer and make a new layer underneath and call it -Sprockets. And I will double-click here to set that as the current layer. And I will also change the color to be something a little different, let's make it blue, OK.
Now let's begin by going to the Solid tab and using the Revolve tool and revolving this cross-section, Enter, and I'd like to revolve that around the central axis so I'm going to snap to the node here and I can force that by typing N-O-D Enter, and then I can click there, and then with Ortho on let's click a point above that and press Enter to complete the revolution. Erase defining objects? No.
So we have a disc and now we need to focus on modeling the teeth. So if we measure this by typing D-I for distance, Enter, we can measure the distance from, say this mid-point to this mid-point over here or this perpendicular point rather, it turns out it's exactly two millimeters. So we need to make a tooth that's two millimeters wide.
Let's go ahead and extrude these two elements. Enter, two millimeters, Enter. Erase defining objects? I'll say Yes in this case. I don't think we need those flat profiles any longer. Now if you'll look closely, you'll see there's kind of a wedge shape here because we extruded these straight back and we're comparing that to this curved rotor. Let's move both of these teeth back from the mid-point here back to the center.
That kind of splits the difference, but we still have that problem. If you look at the sketch of the tooth here, it's supposed to be curved. And it's two millimeters wide, right, so these arcs each should have a radius of one millimeter. And therefore the tooth should only be tangent to the rotor at one point. We can do that very easily by using the Fillet Edge command. Let's set the radius to one millimeter, 1 Enter and then click on these two edges and press Enter and Enter again to accept.
Let's do that again, Fillet Edge and the radius is already set so we don't have to change it again. I'll just click on these two edges and hit Enter twice. So now we have the teeth modeled correctly, however, they're not in the right place. Let's rotate them around the central axis of the rotor, but first we have to reorient the UCS. Type U-C-S, Enter, Enter. So now the blue axis is going up now rotate, R-O for rotate, Enter, select the teeth.
Select the end of the sketch here, which is at the center of the rotor. And I don't know exactly how many degrees to rotate this, so I'll use the Reference option. The reference angle will start here and go to the middle of the tooth and it's going to end at the center point here on the sketch. And that moves the teeth over exactly.
Now I need multiple teeth going all the way around. So I'll use the Array command, and array these two teeth all the way around the perimeter using a polar style array. The center point of the array is right here and we need a number of items and by default it just gives us six. Let's change that to 28 and press Tab. We have all the teeth that we need. Make sure that it says Associative so that all the teeth are connected in a single object, and then click Close Array.
Erase defining objects? Yes. So now we have an object here, which is the polar array containing all the teeth. We have another object here, which is the rotor itself. Okay let's see how this looks in the context of the rest of the drive train. I'll go to Home, Layers, Unisolate. And you can see that we've modeled this at the center line of the transmission.
So we need to move it up 48 millimeters according to this sketch. So I'll use M for move, select the teeth and the rotor and move that whole sprocket element up 48 millimeters using Ortho. And then move it again so I'll type M, Enter, P, Enter for previous, Enter, and move it forward in the red direction 500 millimeters. Let's take a look at it over here now.
So it looks like it's in the correct location.
- Establishing a layer convention and property filters
- Extracting isolines
- Trimming and extruding surfaces
- Lofting cross sections
- Sculpting watertight surfaces into solids
- Sweeping and sculpting
- Revolving boundaries to create surfaces
- Welding objects together with Fillet Edge
- Rebuilding NURBS surfaces
- Offsetting a surface