Learn how to rotate the user coordinate system twice, once using the object options and again about the Y axis prior to drawing a cross-sectional circle. Learn how to extrude this circle to act as the bicycle down tube.
- [Instructor] Let's turn our attention now to this tube in red, which extends from the bracket that we just modeled, all the way up here to where the seat post goes and slips inside of it. So I'm going to orbit around and get a different view of this. And let's just take a look at that. So this seat tube is at some angle with respect to the user coordinate system. So the access tripod that I'm moving around lines up with the UCS icon down here in the corner.
Can you see that? It always does. So what I'd like to do now is change the UCS so that it lines up with the geometry here that we're trying to model. So I'll type UCS enter, and then I'll use the convenient object option right here. And then I'll just click on this red object right there. And that reorients the UCS so that it's parallel to this geometry. And that will make things easier for us. Now if I draw a circle right now, that circle will be on the XY plane, so it's on the same plane as the rest of this two-dimensional information.
What I want to do is get a circle that's rotated so that it will act as a cross section for this tube. So to do that, I need to move the UCS one more time. In particular in this case, I need to rotate it around the green axis, so I'll type UCS enter, and then I'll click on the Y axis right here. And then the default in angled brackets here is 90, so I just need to press enter and it will rotate that 90 degrees around the Y axis.
Now the red green plane is in a different orientation as compared to where it was before. If I draw a circle now, it will have the correct orientation for this tube. However, if I orbit, you'll see that that tube is not-- That circle, rather, is not in the right location yet. So I'm going to delete that. In order to get that circle in the correct location, we need to use object snap. So I'll type CI for circle.
I'll hold down the shift key and right click to open up the object snap menu, and I'll choose nearest. And then I'll click at some arbitrary point along this purple center line to specify the center of the circle. And then I need to specify the radius over here perpendicular to this red edge. So that circle should be in the correct location. Now following my strategy of modeling half of the bicycle, what we should do is cut this circle in half, so I'll draw a line from this quadrant or intersection point to the opposite one over here, and then I'll use the two-dimensional trim command.
That's TR enter for trim. I'll select this line as the cutting edge, enter, and then click on the lower part of the circle to trim it, enter. I actually don't need this line, so I'm going to click on that to select it and press the delete key to get rid of that. Now I want to move this circle back so that it's beyond the bracket element. To do so, I'll use the move tool, M, select this, enter, and start moving it, and I need to make sure that I have either ortho or puller tracking mode on.
Either one will do, I'll use ortho, and that allows me to move this orthogonally along this direction. I'll just move that well beyond the bracket like that. Because we used ortho, we can rest assured that it's in the same parallel position. So now I will go ahead and extrude that as a surface. I'll click on that, enter, and I'm going to extrude that all the way over here, and snap it right there.
And then, let's just come over here, take a look at this, I'm going to use the 3D surface trim command up here. It just says trim on the icon, but the actual command is surf trim, and then it says select surfaces or regions to trim. I want to trim this surface, enter. Now it says select cutting, curves, surfaces or regions. That would be this element, enter.
And now it says select area to trim, and what you do is you click on the side of the object that you want to trim, either this side or the other side. I'll click on this side to trim that away, and then press enter to end the command. So we're left with a tube that is trimmed by and terminates at the bracket. And then this here is currently on the 3D frame layer, and it doesn't really need to be. This is more of a profile that should be on a 2D layer, so I'm going to select that, and I'll type PR to open the properties window, and I'll change the layer to the 2D frame layer like that.
That way we can maintain a copy of that for the future, but we can easily toggle it off when we want to view the 3D model by itself later on.
- 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