Insider 12-21-2011

There are many complex shapes in the Iron Kingdoms that basic 3D primitives (cones, cubes, and spheres) cannot keep up with. I thought I'd try to share a few of the more advanced techniques I use in Rhino 3D to build various warjacks and mechanical parts.

The first tool I'll cover is the sweep and rail function. This refers to a physical sculpting and model-making technique that is often associated with the automotive industry. They use clay that is pliable at around 130º and smells terrible because it's made with sulfur (more recent mixtures have omitted the sulfur to make the sculpting process a little more bearable).

After bulking up the main shape of the automotive model with hot, stinky clay and letting it cool so that it becomes rigid, channels are cut where the model needs a contoured surface, and a pair of metal strips are inlaid into the channels. The metal strips are the rail half of the technique, and the sweep refers to either a straight or contoured scraper that is pulled along the rails to remove excess clay.

Having personally used the old mix of clay on school projects, I can say that using a sweep and rail function in Rhino is way easier and does not leave you with scalded hands that smell like rotten eggs. Below are examples of a straight and contoured sweep in Rhino.

Another set of functions I often use to create uniform rivets on uneven surfaces is "curve projection" and "array along curve".

So let’s say the powers that be request a row of rivets on the bottom edge of the Man-O-War boiler. I would start by drawing a curve where I would want the rivets to be; then I would project the curve to the surface:

Once the projected curve is in place, I would create a sphere primitive at one end of the curve, which will be my rivet, and use the "array along curve" function to create as many rivets as needed along the given curve:

That’s all for now. Next time I’ll talk about one of the models I’ve worked on.