Need help generating complex topology...

[psyclops]

Hi,

I am having a really hard time trying to figure out how to generate some complex topology with SW 2004. The easiest way to visualize what I'm after is to imagine a looped road that appears circular when viewed from abouve but that goes up a hill, over and then down the hill before looping back on itself. The road cross section is always flat (no tilt side to side) but it's forward/back gradient is always changing.

I tried creating the edges of the surface (sides of the road) as splines and then revolving a square profile using the revolved boss with the spline as a guide curve but it does not work, as the profile stays orthogonal - I need it to revolve about the center point. Does anyone have a suggestion as to how I can achieve this?

cheers,

nick.

 

[SBaugh]

Do you have a picture of what your looking for?

Regards,

Scott Baugh, CSWP
3DVision Technologies

http://www.scottjbaugh.com

Merry Christmas
faq731-376
faq559-716 - SW Fora Users

 

[CorBlimeyLimey]

You need to use the Sweep function instead of the Revolve Boss. Check out the Revolves and Sweeps section in the Online Tutorial.

 

[psyclops]

There is a picture of something similar here:

http://www.gotrobots.com/tmp/complex_topology.gif

This was my first attempt at creating the solid; it is not quite correct, however, since the 'humps' are created by taking linear cuts through the body, and therefore the cut is not radial at all points. I am trying to get the direction of the cut pointing to the center at all times so that a line from the center to the edge will always meet a flat surface. Tricky.

cheers,

n.

 

[Theophilus]

I've done this before with a sweep. You can do it in different ways.

One way is to extrude a circular surface upward to represent your circular mid-point. On this surface you will sketch a 3D spline. You can add points in a single 3D sketch coincident to your extruded surface, at dimensioned distances from your "ground" or Top plane or whatever you use as your datum.

Next, open another 3D sketch and use the spline tool to move through the points you drew. Create a tangent loop, and you've got your spline for a sweep path.

Pick a point along the spline, then insert a plane normal to the spline curve at that point (check Help if you haven't done this before). On that plane, sketch your profile.

I have a feeling you'll have problems keeping your swept solid perfectly concentric with your circular base, so below is a slight alternate.

Instead of sweeping a square for a profile in a solid format, sweep a horizontal line and create a surface. After you get the surface you need, extrude your solid up to this surface, then hide your surface. Your extrusion will be a circle within a circle to maintain a concentric relation with your base. You can also use the surface to cut away material you already extruded using a surface cut.

That should work well for you. Good luck.

Jeff Mowry
Industrial Designhaus, LLC

http://www.industrialdesignhaus.com

 

[psyclops]

Excellent! Thanks for your help Jeff, I generated the solid.

My first attempts at following your instructions gave me some rather frilly and yet quite pretty solids, but after reading your reply a couple of times I realized it was the insert plane normal to the spline bit I was missing, and after doing that I was able to sweep using my pre-existing inner and outer splines (the edges of the road in my metaphor) as the guide curves, with a simple circle as the path and it worked beautifully.

Nice one!

cheers,

nick.