Thursday, August 15, 2013

Helix, Helix, Helix...

When did you start using Revit?
In my case, it was the year of 2010. I've been using SketchUp for Modeling & Design, 3ds-max for rendering, and Autocad for drafting until then.
Revit was just awesome for me at the first time. But it took not much time for me to realize that modeling in Revit is not that easy comparing with SU or 3ds. Practicing was the only way to make it easy for me.
Few month later, someone asked me about how to make a Helix with Revit. Hmm.. that wasn't an easy mission for me at that time. And this one simple question made me to begin a journey to Helix.
I started googling. It was the first time for me to get to know Zach's blog. And This was what I read.

Step 1. Stacked Points

I've tried to follow, but could't get some parts to make it at that time.
So I found my own way like this.

I  stacked one point after another. and gave parameters rotated like this
This worked exactly like one of Zach's.

But this has a little faulty.
When a rectagle profile attached for sweep, it doesn't maintain it's axis.
I found it's because the workplanes that follow the path are rotated when the path is 3D curved.(This still makes some troubles when i use Adaptive Components though I found some ways to avoid it. This video shows one of the ways)

Step 2. Using Unfolding

As known, If a helix unfolded, that makes a straight sloped line in rectangle like this.

So, I made another version of helix using this.

I made two curves at xy workplane for paths and drawn profiles for them.

I could get another fine helix.
And with some more formulas, this kind of Spiral-Helix slope can be made.

And this is the only way I've been using in my real projects. Like this.

Step 3. Divide Path

From the version of 2013 of Revit, a new feature of Divide Path showed up. And patterns can be arrayed on divided paths or grids of surfaces.

So I went back to my helix journey with this feature.  And I could make a circle includes helix.

Step 4. Formula & Pattern

Before explain Step 4, you need to understand how UVgrids work on surfaces. I used this for the last step.

The picture above shows how the number of grid works when grids rotated. If you rotate the angle of grids, the distance between the first and the last of grids increases to fit to the original rectangle. I used this with formulas to make patterns to be unfoldings of helix.

angle=atan((height/(number of grid-1))/width)

This simple formula can give me angles from length, width, and number of grids in any rectangles. and this can be an unfolding pattern of helix like this video.

One of the days with rain, I made the last video. I was just bored.

I rarely use helix in my projects, but could get better skills and understandings that always being used from this journey. (you can download the last family here)

Enjoy :-)