Angling Reference Planes and Associated Extrusions

[Anonymous]

Hello Revit Community,

I'm trying to create a pendant Light Fixture family whose pendant changes the angle it is suspended at based upon the family type selected.

As you can see in Screenshot #1 I have created  a reference plane from which the pendant is extruded from and then the constraint is associated with that reference plane. In my mind, when I change the angle from 90.00 degrees to 95.00 degrees, it should pitch the pendant along with the reference plan, but maintain the same center point. It also should remain oriented the same.

What I have found instead is what you see here in Screenshot #2, #3 and #4. Sometimes solely the center point of the extrusion changes, other times both the center point and the orientation of the extrusion change. I have tried creating reference lines and locking them to reference axis as well as to the extrusion, but I always get the error message about over constraining the model.

I have also included the family with this post. If anyone can provide me with some insight as to what is going on here and how to fix that I would greatly appreciate it.

[Anonymous]

Sorry Everyone,

Forgot to attach the family file. Here it is.

[Ilic.Andrej]

I think you made two mistakes.

You constrained the extrusion on the ref.level. Since the reference plane which is the extrusion host is being rotated, don't use linear dimensions on ref. level. Use it on that plane which is being rotated. Under "Work Plane" tab, click "Set", click "Pick plane". Pick the reference plane which is being rotated. Go to ref. level view and then use linear dimensions.

Second, don't use two dimensions which are the same, constraining the same element with same parameter. No need for that.

I just deleted the dimension in ref. level and attached the family

[Ilic.Andrej]

Not easy to center this... Its cause reference planes don't have beginning and the end. I so pose there s gotta be a way around it...

[loboarch]

Reference planes do not have a beginning and end so they don't rotate. Reference LINES do.  If you are attempting any kind of rotational constraint, you must use reference LINES.  Lines have logical end points.

[barthbradley]

I'd also suggest modeling the ellipse in its own family (Generic Model, Work plane Based checked, Always Vertical unchecked), and then nest it into Lighting Fixture Family --- and place it on a Ref. Line as @loboarch said. 

[Ilic.Andrej]

Here's my solution:

I created a sweep which hosts the extrusion. Ofcourse, the sweep is invisible. The sweep path and profile are constrained with parameters. One of the parameters is Angle of Fixture, but you also have parameters for fixture dimensions. Angle of Fixture is constraining the sweep profile. I attached the family, check it out. It works. Sweep path lies on the reference plane you created. If you want, you can create a parameter which constrains the distance between that reference plane and the light source. 

[barthbradley]

Interesting @Ilic.Andrej. How would you control the offset distance of the ellipse from the light source? 

[Ilic.Andrej]

@barthbradley thank you for noticing this. There was a mistake and now i corrected the family. The Fixture Angle must be from the horizontal reference plane, because that plane is going to be movable. This is how we can constrain the distance from light source with a parameter. Its attached.

[barthbradley]

@Ilic.Andrej: Very clever. Kudo to you. 

...I'll just add for @Anonymous's benefit: you need to drill down to sketch mode to find all the "hidden" labeled dimensions. 

[ToanDN]

Here is my take using a different approach:  isolating the tilting the plane and changing the elevation so that they don't affect each other's constraint.