GETTING IN SHAPE

For the past few weeks I have been recovering from a medical procedure and gradually getting back to my normal routine. That’s one interpretation of the title. Another is that I stumbled across Onshape this weekend, and took my first hesitant steps with this cloud based solid modelling package. I’m using the free version, which means that all my models are in the public domain, but I usually share my work freely anyway so that’s not an issue.

So far I have mostly been using my phone. Works quite well with the s-pen. The desktop version is probably faster (big screen, ribbon menu, right click options) but I like the casual aspect of working on my phone (change of rhythm, work on the move). Nothing spectacular yet in terms of results, but a couple of items that improve on Revit’s native modelling capabilities.

I have a long history of trying to create better geometry for furniture and plumbing families with complex curvature. And in recent years the demands of classical ornament have been a recurrent theme. Onshape has potential in both these areas.

My initial attempts to model scrolls and foliage were useful training exercises that fell short of producing viable Revit families. But I hit paydirt with a spiral, rope motif. Onshape has a built-in helix tool which can be used to generate a sweep. Now it’s possible to generate a spiral with the conceptual massing tools in Revit but it tends to lose it’s shape a bit at the ends and you’re going to have to export to ACIS (SAT) format to get file sizes down.

Onshape also exports to SAT, so that’s the route I’ve been using. Phone to One Drive, open SAT with an older version of Revit, scale and explode, save and reopen in 2018. I generally make families in 2018 now. It’s a compromise between having the latest features and maintaining a minimum of backward compatibility. Exploded SAT becomes freeform or direct shape stuff. Here are some examples of public domain models I downloaded. Surface geometry is going to fail in Revit so results will be patchy.  

You can apply materials, cut with voids, add more Revit geometry.

Getting back to the rope moulding, I ended up with a family that might represent a terracotta tile. A row of these tiles produces a nice traditional linear ornament. I previously developed a system that uses the double nested planting hack to generate repeating linear ornament families that scale parametrically via the height parameter. Sometimes I use railings, but this time I went for line based families.

By the way, I struggled for a while, in Onshape, trying to get the pitch of the spiral to look right before I realised that you need two threads, intertwined.  Just another example of the power of the drawing and modelling processes as aids to active learning. You can look at a shape and think you understand it, but the act of recreating it from scratch is much more demanding and therefore more rewarding.

So flushed with success I decided to tackle the "guilloche" challenge.

This is a motif that has many variations. It’s kind of like a flattened out rope moulding. I guess it’s a play on the whole 2d/3d illusion thing. You can read it as a series of overlapping circles, but like many Islamic patterns, the strap work weaves under and over in a subtle way. I did a Revit version using swept blends but the high point forms a sharp ridge. Onshape gave me a nice smooth loft, based on three profiles. I got a bit carried away with the extra decoration. Often enough you get rosettes placed in the inner circles.

For me, Onshape has a lot of potential, and I appreciate their licencing model. Since I'm using it for personal research, I’m willing to keep everything in the public domain, so I get fully functional software for free and access to all my work on all devices from anywhere with internet.  If you are operating commercially, public domain is not going to cut it, so you’re going to buy a license.  Apart from the secure storage for your work, you’ll get technical support and some extra admin tools.

I know some content creators use Rhino or Inventor to create more complex BIM geometry, but I don’t have access to those tools, so I’m going to give Onshape a try.  Still a lot to learn to achieve a decent level of fluency, but not a bad start.