NX6: Section Sweep

Catia V5 isn’t the only kid in town with a wicked-sweet parametric sweep tool. Unigraphics NX6 has a new and improved interface for its parametric “section sweep” tools, offering pretty much everything you get in the Catia sweep function, and a few other nice little add-ons. As a class-a surfacer, I use these kinds of surfaces constantly! Reliable, controllable, and squeaky clean, procedural surfaces can make your life as a surfacer much, much easier.

In this video series I’ll be going through each of the major types of section sweeps, explaining what they do and how they work. I’m making no assumptions here; anyone with a basic understanding of the concept of 3D CAD, the idea of surfacing, and a high-school knowledge of geometry will be able to follow these tutorials.

Previous versions of NX had an impossibly cryptic method for the creation of parametric section sweeps, but fear not! NX6 has brought back section sweeps with a vengence, and that factor alone makes NX6 a much more appealing option for me as a class a surfacing tool. Here’s the skinny.

Introduction and file setup

Today we’ll be looking at lots of different “section sweeps”, but first we’ll need to set up a part file and create some very basic geometry. In this video we’ll be creating a few sketches and extrudes (one with draft, one without) to use as construction geometry for our sweeps.

Fillet-Rho conic-section blends (with basic laws)

The Fillet-Rho conic surface is pretty much exactly the same as the two-guide conic section sweep in Catia V5. It lacks some of the interface niceties, but has a few of its own. We’ll not only build a conic section sweep here, but we’ll also use a basic law function to vary the Rho value across the surface.

Ends-Slope-Rho conic-section blends

This is one of those funny quirks about UGNX: they like to hide functionality from you by burying it in different tools. This tool is absolutely identical in functionality to the Fillet-Rho tool, except we use curves to define our tangency vectors rather than surfaces. It’s hard to understand why they wouldn’t just combine these tools into one, thus allowing me to have one side have a surface support and the other a curve if I so desired. Ah well, it’s a great tool anyway!

Ends-Apex-Rho conic section sweeps (with combine curves and instance geometry)

This conic is one I almost never use, but on rare occasion it could be very handy. Basically I’ll be using three curves to define end points and a tangency vector (the third curve being the “apex”), and then using a Rho value to adjust how sharp the resulting surface appears.

Three-Point-Arc circular section sweeps

Three points arcs are pretty obvious, right? This one’s short and sweet. But keep in mind the technique I used in my Catia 3-point arc tutorial: the same exact technique could be used here.

Two-Points-Radius and Circle circular sweeps (also uses Extract)

These two are quick, so I put them together into one video. The main thing to watch out for with the two-points-radius sweep is the spine direction: if the spine direction is reversed, the sweep flips inside-out! It’s not a terrible thing, but it would be nice if they offered me alternatives like the V5 sweep tool.

End-Slope-Arc circular sweep (with QuickPick preferences)

This is a handy tool, so it’s frustrating that they hide it so well. You’ll see me bumbling a little bit in this tutorial, but I leave it in the video because I like for people to see how bad interfaces can mess up even the best of us. I’m a pretty quick study when it comes to CAD, so if I’M having trouble with it, there’s something terribly wrong! In this case confusing naming and poor icons got the best of me!

Ends-Slope-Cubic and Fillet-Bridge (with Through Curves alternative)

This was a really nice discovery for me. It turns out that Fillet-Bridge is actually a more powerful alternative to Through Curves! I demonstrate both tools here and highlight the differences. These two sweep types are NOT available in Catia V5, and I have to admit that I really like them. I could get used to having Cubic-section sweeps available to me! The fillet-bridge sweep is nice, but I’d prefer it to be its own blend tool, out in the sweep menu with all the big kids! I’ll bet most people don’t even know it’s there!

All in all this was a really gratifying exercise. It’s no secret that I have traditionally preferred V5 for surfacing, but one of the biggest reasons has been that NX made section-sweeps so hard to use. Now that they’ve got that more-or-less fixed, I’d seriously consider using NX as a class a tool more often!

Have fun kids. Go get dirty.

about adam: Adam O'Hern is an industrial design consultant specializing in visual brand languages, and has designed products ranging from laptops to power tools, classroom toys to bathroom fixtures, and robots to lint rollers. He has published with 3DWorld Magazine, CGTuts+, and Luxology, and works with Josh Mings of SolidSmack.com on EngineerVsDesigner.com.