Adjustable Angle - Over-Constrained Error

[samuelzergling]

Hey folks-

I am failing to build this family. There is some geometry that I would like to rotate with a parameter. It's an adjustable awning product. When I assign the angle parameter to the geometry and a vertical refence plane, the geometry just gives up with an 'over constrained' error. 

I've tried:

1. Angle parameter from Vertical Reference plane to geometry. (gets a constrained error).

2. I've tried creating a new reference line that is controlled by the angle parameter- but the geometry will not pick the reference line as the new work plane, thus refuses to rotate with the line.

I've been at it an hour and am giving up. Attached is the family. 

[ABR_Kate]

Hi @samuelzergling,

I can’t open the family right now — I'm still on an earlier Revit version than 2025 — but the logic for angle-based rotation is usually the same.

💡Try this approach:

• Create a Reference Line, not just a plane. Fix one end (anchor point), and assign the Angle parameter between that line and a vertical reference.
• Draw your geometry separately, not hosted. Then set its work plane manually to the sketch plane of the Reference Line (use Pick a Plane).
• If it still won’t rotate, try nesting the geometry into another family that already has the reference line working — this gives you more control.

And make sure you’re testing in the Family Editor, not in a project — constraints behave more predictably there.

Hope that helps! Let me know if you manage to get it rotating.

( Revit logic meets stubborn geometry  🌿)

[ABR_Kate]

Imagine you're holding an umbrella and want to tilt it. The handle is your pivot point, and the top of the umbrella is the geometry you want to rotate. But you don’t twist the umbrella by grabbing the fabric — you just tilt the handle, and everything follows naturally.

In Revit, that handle is your Reference Line with the angle parameter. You attach the geometry to that line, and it rotates with it.

If you try to force the solid to rotate on its own, Revit gets confused and throws the "Over-Constrained" error.