## 20100131

### Way Smoother Parametric Helix Tool

This is a Revit 2010 parametric helix family for you to download and abuse. It's good for about 3 full rotations (1080 degrees) before you start having and visible artifacts. You can think of this in some ways as another basic sketch tool like the ones you have in the draw gallery. Just as you would draw an arc, put a profile on it, and make a sweep, you can use this to draw a helix, host profiles on it, and make forms. This includes being able to make in-place sweeps in the .rvt environment of whatever category you want.
To operate, load the mass family into a project and you get a single model line curve. Select the curve and manipulate the 4 parameters to determine the angle of rotation, start and end radius, and height of your helix, either with the shape handles or numerically. You can then use the line for making sweeps and blends or whatever else you fancy. Or you can create geometry IN the family and place complete and flexible forms in the host file.

I won't do a tutorial for how to make this one, but just show the basic principles. If you're curious, you can dissect the family and expand on it if you want more rotations or other functionality. The basic principles are ones that Matt Jezyk and Phil Read started using years ago to make rotated floor plates for tall buildings and has been adapted by others for many other purposes. This family reduces the methodology to a basic geometric primitive that you can use for whatever purpose you like: buildings, ramps, shock absorbers, whatever.

The basic building block of this family is a line that has a vertical offset parameter and a horizontal rotation. I've placed a point on the end of the line and set it to be visible just to make the start and end easier to identify.

The height and rotation of the line is driven by an integer value, so the higher the number, the higher the line and the farther it is rotated. Additionally, the length of the line varies according to the same integer. This allows the length to expand and contract depending on where it is in the helix.

This line is then loaded into a second mass and 17 instances are placed in the same spot. After assigning an integer value 0 through 16, each instance rotates and raises to it's unique placement in the family

The endpoints are sewn together using a spline by points model line. The loaded line family then has it's visibility parameter set to off, so only the spline will show when it is loaded into a project. You can increase the "resolution" of this family, how closely it creates a perfect circle, by adding more lines and increasing the integer value of each, but with 16 increments it's pretty damn round through 3 rotations.

Make Good Stuff!

1. Hey Zach,

great stuff. I especially like the idea of using a single line as a nested family to realize what you needed to do. Thanks a bunch.

Oliver

2. Hate to say it but...

Why the hell couldn't the factory work this out for stairs??

As great as this is (again) it just frustrates me how much work is needed to create what should already be built into Revit.

Getting a bit tired of the excuses now. Revit is a fairly mature product, and there are many, many modelling programs out there these days which are far more advanced and cost far less...

Great work again Zach. But it just highlights what should already be there : |

3. I totally agree with muttleyjbc.

If I show this tutorial to non Revit users, what it takes to make a simple helix, they react with disbelieve. It so strange that an architectural tool in 2010 has difficulty to create the most basic shapes that have been available over 15 years in other modeling packages.

4. Hi Zach,
I don't usually comment on these blogs, but I'd like to thank you for your inspirational work showing off Revit stuff and I think your blog and passion is a valuable resource for Revit users without doubt.

On the score of the above comments I have to agree also 100% BUT, at the same time, not many of those applications can control these forms parametrically which I would have thought is partly the point.
There are only a handful at best (when you exclude engineering / industrial design applications such as Pro Engineer, Solidworks and maybe even Inventor ) etc.

Other than Rhino (now), and obviously excluding ArchiCAD and and Generative Components, which set of the available possibly relevant modelling applications, have parametric controls over modelling functions that equal or outperform what Revit 2010 has currently ?

And this must also be related to the fact that Revit can commute what is done inside the Family Editor and the Conceptual Massing environments to a successive and iterative process for immediate use in a production oriented workflow ( SD/PD/DD/CD stages)
Even Rhino with its latest upgrades and plug-ins in recent weeks of this date, cannot do any of this as yet. What else is there that can be directly compared as apples to apples ?

Revit user since 2002
Modo 401 user

5. Agree w/ Mr. trombe.
Note that some architects/designers play w/ form that isn't real world usable.
Parametric controls are key, especially when "Revise Instantly" is essential to real projects.
Began designing w/ Revit 2001, pre-Autodesk.
Anyone find those funny critiques written by original Revit people, ridiculing cumbersome AutoCAD methods?
Michael David Rubin, Architect/Consultant

6. Hey, I was wondering how to get this to work in the project environment after importing the mass family. I can't seem to "Pick" the path when creating a Model-in-place component with a sweep. Also, I can't select the helical curve after placing a reference point on the curve and drawing the sweep profile to Create form. Using Revit 2012 here. Any more detailed instructions on how to use the curve to host a sweet would be greatly appreciated, thanks!

7. Hi Ronnie,
You need to place the family inside of an in-place mass. You will need to TAB>Select the line inside the curve, look at the status bar when you are tabbing to make sure you have the line and not the whole family selected.

8. Thanks for the reply, Zach, I will give that a try!

9. Any chance you can keep the profile from twisting over as it goes around the helix path? I'm trying to create a large diameter drilling head where the blade stays relativly flat as it turns.

10. Yes, I think there is probably a configuration using an adaptive family using orientation controls, likely "vertical on placement". Check this post:
http://buildz.blogspot.com/2011/03/that-aint-normal-diagnosing-point.html
You could make a similar tool to the diagnostic tripod in that post, using a single line sticking out horizontally

11. It's been three years to read this post for me.
thanks to your great posts(including this one) I could learn many about Revit.
And here is one of my posts which is about helix.
http://plevit1.blogspot.kr/2013/08/helix-helix-helix.html