Join Scott Onstott for an in-depth discussion in this video Building the drive unit using Extrude and Loft, part of AutoCAD: 3D Surface Model Design.
- In this video we're going to start building the drive unit, which is down here. It contains gearing and an electric motor. It allows you to pedal and get electric assist. Let's create a new layer called 3D-Drive Unit, set at current, change the color to cyan. Before we start modeling it, let's isolate some of the layers that we're working on. I'm going to draw a line over here, temporarily, type l+a+y+i, for layer isolate, select this line because it contains the current layer, select this object and let's also get the belt to tell us how much room we have to create this drive unit.
We want to make sure that we don't go beyond the space that we have available. So now I'm going to copy these two paths up in the z direction, let's copy them up 30 units, and let's change those to the current layer, so LAYc Enter, get those two and they should turn cyan. I'm going to move the inner path up another 10 millimeters. It's a centimeter higher and it's still underneath the belt, that's good.
Now go to the Surface tab and extrude this path down and snap it onto the ground like that. Then use Loft and select the inner path and this outer one and press Enter, Enter. We have a lot of detail in here and I'll model some of it. Let's copy these three paths up the aggregate distance, which is 30 plus 10, so I'll type in 40.
So we have those at the top of what we're working on right now. I'd like that to be a planar surface, so I'll type in region, I will select this one and then these two, so we have three regions. The nice thing about regions is you can use boolean operations on them. I'll use subtract, select the largest region, Enter. Then let's select the two smaller ones, that cuts a hole. Down here we have these two circular paths.
I'm going to copy them up, 40, and let's move the inner path down two, that we have a little surface relief here. I'll use the surface tab loft to loft a surface between this path and this lower path, Enter, Enter. This is actually the electric motor. Now we need to create a surface to cap that off. I'll use the Planar Tool, and the Planar Tool allows you to pick points to create a plane, but, in this case, we have a circle so we're going to press the down arrow and choose the Object option and then click on this inner path and press Enter to create that surface.
Over here I'm going to use a solid modeling technique instead. I will extrude this inner path. Actually, it's not there, I need to copy it up, so copy this object up 40 units. Now I should be able to extrude that. It's hard to select, so here's a trick: make a crossing window that crosses through what you want, then remove what you don't want from the selection set.
Hold down the Shift key and click on this object to remove it from the selection set, leaving only the path in the set. Press Enter to go on. Let's extrude this up just two millimeters. Hopefully we have enough room, looks like we just do. Just to refine this, even though this isn't going to be visible, I'm just going to fill it, this edge, to make it look that much more finished.
- Creating layers for 3D modeling
- Extracting isolines
- Trimming and extending surfaces
- Extruding 2D curves into 3D surfaces
- Lofting cross sections
- Converting solids into surfaces
- 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