Circle Radius, Alignment and Dimension

[Anonymous]

Hello.

I have been creating Dimensions for Revit families with extrusions of PlanarFaces with success by creating alignments between planar faces and reference planes and then creating dimensions between two reference planes.

For CylindricalFaces however, I am finding that document.FamilyCreate.NewAlignment() takes only certain types of parameters and cannot create an alignment between my Cylindrical Face and a Reference Plane.  Without the Alignment, changing the radius does not update the arc radius.

What is the correct way to create an alignment for the radius of a circle?

[jeremytammik]

Dear Melissa, 

I am asking the development team for you. Hang on...

Cheers,

Jeremy

[jeremytammik]

Dear Melissa,

Here is the response from the development team, with some questions for you to answer yourself:

[A] I am assuming that they want to create something like a cylindrical extrusion. I just tried two approaches that seem to work.

1.       Just place a Radial Dimension directly on the arc/circle while in the Sketch of the Extrusion (or whatever else Sketch-based).

2.       A more complicated way to do more or less the same seems to be this:

a.       Create a Reference Line – pick the desired shape – circle, whatever

b.      Place a Radial or Diameter Dim to control the Ref Line

c.       Align and lock, again, the Sketch Curve(s) that define the shape of interest

All this I did interactively and it seems to work. I hope it is just as doable through the API.

[Q] They are developers; they cannot be “in a sketch”, so the first approach is out.

I am not sure about the availability of the second approach either – it is more question for Scott, who is the geometry APII expert.

[A] They don’t need to “be in a Sketch”, so long as we have an API to dimension a CurveElem with a Radial dim. I hope we do. I, as a UI-user, need to be in a Sketch, just so that I can get access to the Curve – this is the only way to get to it in the UI.

I am not sure whether this is of use to you or not, so please let us know how it works out and exactly how you can make use of it.

Thank you!

Cheers,

Jeremy

[jeremytammik]

One more thing: the radius can be controlled by labeling the radial dimension.  No need for alignment.  To control the position of the arc, you need to align its center to reference planes.  I still don’t know, however, whether API provides access to the reference representing the arc’s center.

Cheers,

Jeremy