Tuesday, April 2, 2013

Adding Mullion Profile Parameters

In the recent post "Custom Profiles" (http://curtainwallbim.blogspot.com/2013/02/custom-profiles.html), ghaeberle mentioned parametric curtainwall profiles and we'll take this opportunity to present the procedure for doing just that.

When creating the profiles for curtain wall mullions on a large project, you'll notice the number of mullions growing quickly.  The captured mullion that you thought could be used in most places may need to be modified because of changes in the glass thickness, changes in the infill material (glass, terra cotta, aluminum composite panel (ACP), etc.), allowance for design features, or a change in the system, just to name a few.  By adding parameters to the mullion profile family, changes can be made quickly and the new variation can be added to the project.  Here's how:

1)  Open a mullion profile family (.rfa).  The one shown in the fig below is from the Custom Profiles tutorial on this site.

2)  In the Properties panel of the Home tab, click the Family Types button.

3)  This opens the Family Types dialog box.  Each parameter must be named and then a dimension can be associated with each parameter.  Click the Add button in the Parameters section of the Family Types dialog box.

4)  In the Parameter Properties dialog box that opens, choose Type as the parameter type then enter a descriptive name in the Name field.  Spaces are acceptable as parameter names, as are underscores and hyphens, but we don't recommend them.  Underscores between words can offer a degree of visual continuity that a space doesn't and hyphens can be interpreted as minus (-) signs in some schedules.  Make sure Length is selected as the Type of Parameter then click OK.

5)  The parameter is added to the Dimensions category in the Family Types dialog box.  Repeat step #4 until you've added all the parameters that you need.  If you realize later that you missed one, you can repeat steps 2 - 4 to add it.

6)  Add dimensions to your profile that correspond to the parameters you created.  These are not visible in the project that the profile is loaded into, so you don't need to spend much time making them neat.  You can also change the scale of the current view to reduce the size of the dimension.

7)  Select a dimension then, from the Options bar, click the Label drop-down list and select the corresponding parameter.

8)  The parameter name is added to the dimension name indicating that the dimension value is driven by the parameter value.  Repeat step #7 to associate the remaining dimensions to the parameters.  In the image below, you'll see that the overall system depth does not have an associated parameter.  This value is driven by the sum of the System_Depth_FOG and Cap_Depth parameter values.  This dimension cannot be locked as this would create a conflict should the other two dimensiond be modified.

9)  In this example, the Mullion_Width and Cap_Width parameters should move the lines equally in opposite direction.  To force this, add and place a multi-segment dimension from the left vertical mullion line to the reference line to the right vertical mullion line.  Click the Toggle Dimension Equality icon (The EQ above the dimension).  EQ replaces the actual dimension to indicate that the vertical mullion lines will remain equidistant from the reference line.  Do this for the width of the cap as well.

10)  Save the file then click the Family Types button to open the Family Types dialog box.  The parameters are shown with their associated values.  To modify a parameter, change the dimension in the Value column then click Apply to see the result in the view.

From here, you'll just need to save the file after the necessary parameter changes then load the family into the project.  Remember, like any other family in Revit, it will overwrite all instances of the same name in the project.  If this is to be an additional profile in the project, perform a Save As and give the profile a unique family name before loading it into the project.  See the Custom Profiles post to see how to assign profiles to mullion types.

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