Saturday, April 28, 2012



Please read the previous blog post titled “ROTATION RIGS THAT DO NOT USE THE ANGLUAR DIMENSION “first before continuing.

The Revolve method is another alternative method, aside from the Ride the Rail method and the Open Reference Circle method that could be used to create rotation rigs that do not use the angular dimension. The Open Reference Circle method as shown above will not work when the value of the arc angle is at 0 degrees or at any value of 0+360*n degrees. Knowing this limitation, and the demand to have it “fixed” via comments and email feedback, pushed me to create a rig that was free of this limitation and that could be used in the classic family editor environment. The Open Reference Circle method breaks when the value of the arc angle is zero because it is not allowed to have a zero length. However, if the length were to never change then the problem would be solved.

It was this fundamental concept that had me realize that the Revolve element could have a constant angle value and have its start and end angles move together. This would allow the arc angle to never be zero. Also, you are able to define the end of an open revolve element as a work plane.

From this, I created the “Revolve” rotation method as shown in the rotation rig above and notice that it uses the preset revolve form parameters of the start and end angles to control the angle NOT the angle dimension. Basically, it is the Open Reference Circle method with the revolve element swapped out for the reference arc. This way, the revolve element could be a constant arc length/angle and this in turn allows the end angle to “chase” its start angle. 

Below is a step by step process on how to create the Revolve rig and how it would specifically apply to a door family in Revit.

1.   First start a new door family from the default family template in Revit. Go to the reference plan view.
2.   Set the reference plane to the preexisting reference plane titled "exterior". This will host the revolve profile

3.   Go to the interior view, with the work plane set to "Exterior", create a rectangular profile where the top of the profile is at the floor line
4.   Select the revolve axis line as the vertical reference plane that intersects the center of rotation. Click ok when done and the revolve element will be created.
5.   Click on the revolve element and make it “not” visible. This will make the revolve element not visible in the project environment. However, this element could be left as “visible” and be changed to look like a door handle instead of how the revolve element looks in this example.

6.     Create three angle parameters
a.     Create an angle parameter called “INPUT”
                            i.      This will be used as the input angle, what is traditionally used to define how “open” a door is.
                            ii.      I like to use the end angle to control the back side of the angle instead of the front because it is easier to work with
b.     Create another angle parameter called “START” and give it the formula as shown above
c.     Create another angle parameter called “END” and give it the formula as shown above.

7.   Assign the “START” and “END” parameter to the start and end preset parameters of the revolve element respectfully.

8.   Go to the top down 3d view and set the work plane to the end of the revolve element, this is done so that the reference line that will host the door geometry is placed at the correct plane.

9.     Create a reference line by picking the face of the end of the revolve element.
10.   Congratulations! The Revolve rotation rig is now complete.

11. Set the reference plane of the host reference line to receive the door geometry, create the door geometry on the hosting reference line. The final elements should look like the image above.
12. The door geometry will not be covered in this posting however; it is very simple to perform.
13. The following image below shows the rig in action in the door family and in the project environment.
14. A rotation rig was set within a door family however; this method is applicable to host any geometry, in any classic family editor.

Above is the example door family at different angles that are hosted on a wall element in the project environment that is using the open reference circle rotation rig. Please note that any angle is possible.

In conclusion, I have given three rotation rig methods that do not use the angular dimension parameter in these last two postings. These methods are the Ride the Rail method, the Open Reference Circle method, and the Revolve method. It is always my intention to offer the Revit community “alternatives” to traditional modeling methods in Revit. I want to share the methods that I have created and that I am successful with. I do not want to push or demand that anyone use these methods. I want everyone to decide for themselves if they should use these new alternative methods.


J said...

Those were what I call the "Method Pusher Method" Postings (and I mean that in a good way ;-)

Klaus Munkholm said...

Great tips Marcello!! We had a similar "challenge" at the revitforum last year, and came up with a almost similar way to use profiles to rotate the geometry... Got a "little" off track, and we ended up doing a fully parametric clock :O)

Darren Snook said...

Hello Marcello
Good post. Rotation is always a problem
I posted on a method for rotating annotations at I've only done this for tags, but the principle may work for 3D elements in the context you've outlined (I think it will, but haven't tried it)

NKramer said...

Is there an upper limit to what Revit will accept for degrees? I tried a random angle of 3636376363.000° (yeah its unrealistically high...) and it broke the back angle parameter.

J said...

more than 360 degrees? really?
The piece works based on a circle...if you can find a circle, even a revolution that's possible greater than 360 degrees then it is a number that I think at best is coterminal 425 is coterminal with 65, so still not possible.

Unknown said...

Just to say Thanks- very straightforward rotational method

Unknown said...

I attended your animating revit families at AU this year.

Just applied it to a real world problem. Worked Great! Used the revolve method to animate a static articulating boom personnel lift family. was able to demonstrate to the client an up and over access in a confined space.

Whats the problem? there no problem, Give me something hard!

Thanks for sharing!