Revit Family Formula Examples and Tricks

When creating formulas in a family it is helpful to have a go to list of examples. Here is mine.

IF Statement
IF (Length < 30′, 2′ 6″, 4′)    
     If the Length parameter is less than 30' x = 1 , y = 22'-6"
     If the Length parameter is greater than 30' this parameter will have a value of 4'-0"


IF that Returns a String
IF (Height > 30′, “This thing is tall”, “This thing is short”)     
     If the Height parameter is greater than 30' this parameter will return  This thing is tall
     If the Height parameter is less than 30' this parameter will return  This thing is short
Nested IF Statements
IF (Length < 35’, 2′ 6″ , IF (Length < 45′, 3′ , IF (Length < 55′, 5′, 8′ ) ) )
     If Length is less than 35', this parameter will have a value of 2'-6"
     If Length is between 35' and 45', this parameter will have a value of 3'
     If Length is between 45' and 55', this parameter will have a value of 5'
     If Length is greater than 55', this parameter will have a value of 8'

IF applied to a Yes/No condition
Length > 40' 
     If Length is greater than 40' the the statement is true and the Yes/No check box is checked
     If Length is 40' or less the statement is false and the Yes/No check box is NOT checked


IF OR
IF (OR (A = 1 , B = 3 ) , 10 , 5) 
     If A = 1 or B = 3 this parameter will have a value of 10
     If A is not = 1 and B is not = 3 this parameter will have a value of 5


IF AND
IF (AND (x = 1 , y = 2), 8 , 3 )     
     If x = 1 and y = 2 this parameter will have a value of 8

     If x is not = 1 or y is not = 2 this parameter will have a value of 3

Some Formula Tricks of the Trade

This or That only with a Yes/No parameters

By specifing that metal can not be true while Wood is true the user can only specify one of the two materials. They both can not be checked at the same time. This can be used for visibility where a left or right access panel may be required but never both.

Pick One and Only One

Here the condtion number will allow only one paramter to be true in a list. Associated with a type, you could control a ton of things simply back picking the correct type.

"Don't Change Me Bro"

If you need some text to not change, put that text in the Formula column with quotes around it. It greys it out in the Value column. This should stop the majority of users from changing its value.

Swapping Nested Families
In a bookcase family with a nested shelf family, follow these steps to add a parameter that will allow the user to switch from one type of shelf to another.


1. Open the original shelf family and save it as the second shelf option. Add something to make it different. 

2. Load this new shelf into the bookcase family, but do not place it.


3. In the Family Types dialog create a new Type parameter named “Swappable Shelf”. Make its discipline Common, its Type of Parameter and group it under Constraints.

4. When you select the Type of Parameter Revit will open the Select Category dialog. Pick Generic Models.

5.  Select the original shelf in the bookcase family now. In the Properties dialog, look for the Label parameter and change it to “Swappable Shelf”.

6.  In the Family Types dialog Create 2 shelf types, Shelf Type 1 and Shelf Type 2. Associate the swappable shelf parameter with the appropriate type.

7. Flex the family. Change the family type and verify that the shelf changes.

New Year - New AUGI World

The January edition of AUGI World is available online now.  It's chalked full of great articles by good looking authors. Download or view it online today and stay ahead of the pack. Here are some of my favorites;


Joel Londenberg 
Plumbing Systems for Well-Documented Flow

Steve Bennett -
Ini or Outie? Advancing Your Customization of the Revit ini File


Louisa Holland 
AutoCAD System Variable Superstars
 

Using Character Map in Text and Tags

If you were not aware that you can use special characters in Revit to add things like a diameter symbol to text, check out my previous post. In that post I showed how to figure out the key-in required to produce certain symbols just by typing them into the text string. in this post, I'll show how to leverage the many special characters that do not have a key in but existing in the font.


Revit MEP supports oval duct, but the symbol in tags my firm has used since hand drafting is the Greek letter PHI. Unfortunately there is no key in for the PHI character. I can however, use the "Select" and "Copy" buttons to copy the character to the clipboard and paste it directly into a text string.

In this case, the symbol legend.

It can also be pasted directly in a label for a tag as a suffix.

Happy New Year!

Overriding Dimensions in Revit

Say you are putting together a detail that has a dimension in it but for it to look appropriate, things really won't be to scale. What I am getting at, is that you want to put down a dimension that is wrong. Revit won't allow you to override it using the feet and inches symbols from your keyboard. Instead you get this judgmental dialog.

Go back to Dimension Text dialog by clicking on the dimension twice and select the "Replace With Text" option. 

1. Right click in the text field
2. Select "Insert Unicode control character"
3. Pick "US Unit Separator (Segment separator)"

Type a new dimension into the Text box and click OK. 

                                                                Wa-Shaw! 

In the image below these walls are either 8'-0" apart or 1'-6" apart. You don't know, because of my awesome Revit trickery.

Follow the same steps and put a space in instead to clear the dimension altogether.

I realize that this may be perceived as pure EVIL in the Revit world.... and well, because it is.

The Evil Santa Cows says "Moooo, Haha, ha!" 

Merry Christmas!

December AUGIWorld features Industry Insights

The December issue of AUGIWorld serves up plenty of perspective from industry professionals.

In "Halfway to Paperless," Bryan Thompson offers his solution for getting us beyond just talking about a paperless office and actually realizing it. 

Melinda Heavrin, AutoCAD Architecture expert, thoroughly discusses "Material Matters" within the product. In "Stuck in Neutral, Christopher Fugitt offers his view on AutoCAD Civil 3D and what is needed to make that product all it could be. 

Super Families: A Kit of Parts - Many Revit users find families difficult to master. Author Nicholas Kramer makes the concept easy to grasp by breaking it down into parts. 

Advanced Rendering in Revit - Kyle Benedict plumbs the depths of producing presentations using tools within Revit.

and a small offering from yours truly...

Getting to the Next Level - creating a BIM environment goes far beyond implementing Revit and calling it done. Firms will need to spend money, spend time, and build a culture of embracing change, says the author I call me.

Happy 7th Birthday to CAD Shack

7 years today I got frustrated with an editor that changed an article of mine, and I started the CAD Shack Blog so I could write what ever I wanted, when I wanted. 


I was all about Autodesk Building Systems at the time. The Aviator won an Oscar for best picture, New England won Super Bowl 39, Katrina happened, and I paid $2.17 a gallon for gas.


In a lot of ways, things sure are better now. Here's to 7 more years.

Revit - Rooms vs. Spaces

The more I use Revit, the more I want to leverage the information in it. Lately, that has been in the form of calculations for my firm. Today, room area calcs. The architect set up the rooms to calculate the room area from the face of wall. We need a little bigger number electrically to maximize light per square foot, so we want to run these calcs form the center of wall instead. This is easy to change for rooms by changing a setting in the Area and Room Computations dialog.

No matter what we did, we could not get the spaces to also jump out to the wall center as well. A quick look in the Help file exposed the reason why, andwe also picked up a few facts worth knowing and passing along.

So straight out of the Help file, here are things to consider about how Revit Architecture and Revit MEP Share Information when you link a Revit Architecture project to a Revit MEP project.

• Spaces (created in Revit MEP) can be bounded by elements in linked models, in the host model, or in both.
• Spaces are affected by room separation lines. Rooms are not affected by space separation lines.
• Spaces are measured from the wall finish face.
• In Revit MEP, spaces use the computation height that is defined in the architectural model. See Computation Height.
• A space understands in which room of a linked model it resides, and it can report the identity of that room. This information is based on relative locations, not on a link to a specific room ID.
• Multiple spaces can access the identity of a single room in a linked model.
• Rooms can exist in design options. (See Design Options and Rooms.) Spaces cannot exist in design options.
• If the architectural model changes, spaces are not deleted in the host MEP model. Spaces can become unenclosed, redundant, or ambiguous, as they would if the same changes were made in the host model.
• Modification of one model does not propagate to linked models. If the architectural model and the MEP model link to each other, changes to the architectural model may not be matched by changes in the MEP model until the MEP model is opened, resaved, and reloaded.

Pipe Rise and Drop Wrong Size

I had a job the other day and my pipe rises were gigantic!

These are the annotation symbols in single line. To fix things, click on the little angle arrow next to the Plumbing and Piping group label and ensure annotation scaling is being used then change the Pipe Rise/Drop to a smaller scale. Fittings can be changed separately.

You may find that every time you change to a smaller scale it reverts back to the original scale. This is probably being caused by the fact that units for pipe size do not go to a scale that precise. To change that click "Project Units" on the Manage tab, set the discipline to "Piping" and set the rounding to the required precision.

Now take a look at your symbol. Hopefully, things have gotten a lot easier to read.

Imported DWG Files Have Thin Text

There are times when AutoCAD files are required to be added to Revit project files. There two ways to incorporate AutoCAD DWG files into Revit. One is to Insert the DWG and the other is to Link the DWG file. Inserted DWG files remain static and don’t change in Revit when they are updated in AutoCAD. Linked DWG Files update each time the Revit project file is opened or when a reload is forced from with the Revit project.

Inserting is preferable when the DWG file will not need to be updated like a legend, note, existing background, or detail. Inserted DWGs can be placed directly onto a sheet, view, or into a drafting view, depending on its use. 

Linking is preferable when the DWG file will be updated as the project progresses. 

Either way, if your standard text font is Simplex for AutoCAD, when that file gets into Revit it plots too light. My solution is to change the text style in AutoCAD before Importing or linking to Revit.

1.    To maintain the readability of text, use the Style command in the AutoCAD file to be Inserted/Linked and change the Standard text styles font to Zurich Lt BT. 

2.    Navigate to the View or Sheet that requires the Inserted/Linked DWG. (Create a drafting view by selecting the Drafting View tool on the View tab of the ribbon if required.)

3.    Select the Import CAD tool or the Link CAD tool on the Insert tab of the Ribbon.

4.    Browse out to the required DWG. Before clicking the Open button, Select from the drop downs of what Colors, Layers, and Positioning.  

5.    Click Open to place the DWG file in the View/Sheet.