In this video learn how to model the hub transmission and cut holes with alternating spoke patterns on the two flanges.
- [Instructor] Next up is the hub transmission shown here in red. So the purpose of this transmission is to vary the gear ratio with internal gears, not shown, which connect to the sprocket and the wheel. Now, it connects to the wheel using these flanges that stick out above and below. And these flanges have holes drilled through them. And you can see over here in the plan sketch, that we have the spokes coming in and connecting to these holes.
But not shown in the plan is the fact that we have two different flanges above and below. And so the idea here is that we have holes drilled alternately every other circle. So let's say the top flange has these spokes running this way. And so every other hole would be drilled in the top flange. And again, on the lower flange you'd have holes opposite. Like this spoke would be on the lower flange, this one would as well.
So we just need to keep that pattern in mind when we're modeling this. Let's begin by copying this array of circles and this large circle over in the red direction 500 millimeters. And then we'll come over here and take a look at this. Let's reduce the complexity of what we see on the screen by going to the home tab under layers and using the isolate tool to isolate this layer.
And as it stands right now we have this polyline which represents the outline of the transmission. It's symmetrical on both sides. So we can pick either one to create the profile that we will revolve to generate the transmission. However, I don't want to do it as a surface because thinking ahead, I know I'm going to have to drill holes in these flanges and the easiest way to do that of course would be to use a bullion tool which is only available in the solid tool set.
So what I'd like to do is make this a closed shape, and I can do that by first making a new layer. So right now this is on the 2D transmission layer. Let's make a new layer for that called dash transmission. And I'll set that as the current layer. And then I will draw a line from this endpoint to the endpoint below. And then I'll use the join command, J enter, select that line and this polyline, enter, and that generates in this case a spline on the 3D layer.
I can use this as the basis of my solid object. So I'll go over here and choose revolve. Revolve that object, enter. I want to revolve it around the center of the axle so I'll click here, and then click a point above using ortho. And then press enter to complete the revolution. And I'll say I don't want to erase the defining objects, no. So now we have the overall transmission with the flanges. And now it's left up to us to drill the holes as we need them in the two flanges.
We have the hole outlines here in plan, however it's an array. You can't extrude an array directly. Instead you have to explode that first, so I'll type E-X-P, and I see a list of commands here and there's explode. I'll choose it, and I'll explode this array of circles, enter. And then before doing anything else I'm going to say extrude. And then I can use P as the previous selection.
I'll choose P and it gets all those circles so I don't have to select them manually. And then I'll press enter to end select objects mode, and I'll extrude these up so that they go through the flange above. Erase defining objects, no. Now I want to have every other hole cut in this upper flange. So what I can do is move every other cylinder down. So I'm just going to make a selection manually now, going around here.
And getting every other cylinder. And now I'm going to move them down so they penetrate through the lower flange. So now I can subtract these cylinders from each flange. To save time, instead of having to do multiple subtractions, I can union all these cylinders on the top together. So I'll select them. This will unify them as a single object. And then I can use subtract and subtract from the transmission, enter, this set of cylinders, enter.
So now we have holes cut in there to accommodate those spokes. Again, down below we'll do something similar. We'll union these cylinders together. We'll have to orbit, so I can select the others. Enter, and then subtract the transmission first, enter, the cylinders second, enter. So now we have holes drilled opposite each other in the same kind of pattern, alternating above and below.
So let's end layer isolation by going over to layers, layer unisolate. And then move this object 500 millimeters over into position.
- 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