Wednesday, December 21, 2005

Starting in Revit Families








  • Starting in Revit Families:

  • Setting up shortcut paths in the Option dialogue box.

  • Understanding Reference Planes

  • Understanding Parameters

  • Revit Formulae (Basic)

  • Aligning in Revit

  • Loading a family into a project.

  • Changing Properties of a Family in a Project



  • A simple definition of Type Parameters & Instance Parameters


  • Exercises to follow:

  • Nested Families

  • Sharing material Parameters

  • Switching visibility on & off of objects in families.

  • Revit Formulae: Including:

  • Array Formula

  • If Parameter

  • Nested If Parameter

  • Tan formulae

  • And many many more…….


















Before starting any form of family creation, create a library where you will save all of your Revit Families.
You can path to this shortcut by going to “SETTINGS > OPTIONS>FILE LOCATIONS” (image placeholder)

When starting a Revit Family file (*.rfa) you firstly need to know what it will “belong” to.
So you will have to ask yourself, what is this family part of.
ie. You would not want to have a door as part of a cabinet family as it will not behave correctly.
Once you have decided what this family is, select a new family from the standard family templates in your metric library.



You will notice in the image the following points of relevance which are highlighted in Red:
Select Metric Templates from your Metric Template Library.
These file types are of the type *.rft (Revit Family Template).
I will select a Metric Generic Model.
(Remember if you select a Wall Based/Ceiling based or any other type of template, you will only be able to use these on the hosts to which they belong, ie. A wall mounted shelf would be a wall based family, as you would need a wall on which to host it.)


You will see that the template opens a plan view containing 2 reference planes. (image placeholder)
Understanding Reference Planes
If you select these planes, you will see that they are named, as above.
These are workplanes.
To understand workplanes correctly, when training I like to explain a workplane by using a simple analogy: In the open blank space of the Revit work area, you need to know where you are working.
Imagine holding up a piece of cling wrap stretched from one side to another. In this blank area you now have something on which to define a working area. (ie. You could draw on this clingwrap)
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In a 3-d view you can select and activate which reference plane you want to work on.
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As well as show where the reference plane is by pressing the work plane visibility icon.
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I have now selected the Center (Front/Back) plane and placed model text on it, in a 3-d view with the reference plane visibility ON.
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At this point you can start adding in solids into the family template.
In the project browser, go to the Floor Plan Ref. Level.
Understanding Parameters
We are going to set up and add a few parameters to a simple shape to be able to control it’s sizing.
Add in a few reference planes, as shown below.
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The spacing and sizes are irrelevant at this stage as these are going to be “parametized” at a later stage.
Dimension the verticals and horizontals as shown.
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Select on these dimensions and select the small EQ sign.
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Do this on both dimension strings.
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Do not re-dimension and equalize the opposite sides, otherwise your family will be overconstrained.
Dimension the horizontal and vertical from the outer sides, as shown below.
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If you select on one of these new dimensions, you will notice that a new toolbar appears.

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You will now be able to add a parameter to this dimension, by selecting a label at the position indicated above.
Select Add Parameter.
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This will bring up the dialog box above. We are going to term this parameter type as a Family Parameter. (Shared Parameters explanation to follow)
Under Parameter Data you must give the parameter a Name.
Group the parameter as Constraints. (Instance and Type parameters, explanation to follow.)
Repeat the process for the vertical dimension.
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From the Design Bar select Family Types:
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Notice under the Constraints section. The parameters that have been added can now be seen.
Revit Formulae (Basic)
To add a basic formula, you can type this under the Formula Section of the dialogue box.
The formula that will be used in this example will show that whatever the length is, the width will be half of the length. (Width = Length / 2)
It is very important to remember that any Formula is case sensitive to the actual parameter.)
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To test these parameters change the Length in the Value tab, and press Apply.
The Width automatically changes it’s value.
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The Reference planes should look something like this:
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To continue with adding a height parameter, you should go to an elevation view (Select Back elevation in Project Browser)
You will see the reference level and the 2 reference planes you created.
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Repeat the same processes above, to add a height parameter and thickness parameter.
NB. It is important to remember that you are working in an elevation view.

For interest sake you are working on the (Center Front / Back) plane.
Your reference planes should be set up to look like the image below.


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These parameters can be checked in the family types dialog box, which should now look something like this.
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It is very important to keep checking parameters before you start applying solids to the family.

(image placeholder)Go back to the floor plan – Ref. Level
From the Design Bar, Select: Solid Form (Solid Extrusion)
Notice that the design bar has changed, you are in a sketch mode.
Select the lines and draw a rectangle inside the ref. plane area.
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You could select the rectangle tool and draw from the intersections.
(If automatic sketch dimensions are switched on in visibility graphics then you could see that a reference of 0 will be shown when drawing on ref. planes. However this exercise deals with aligning and constraining to a ref. plan)

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Aligning in Revit
Select Align from the toolbars.
You always select the object you want to align TO first, then select the object you want to align.
As you align the first line, you will see a small lock appears on the line.
Click on the lock, this means that sketch line of the solid object is aligned to the referring ref. plane.

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(Unlocked = Unconstrained)

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(Locked = Constrained)








Repeat this process for all 4 sides.
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To make the object more visible select Shading with Edges
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Go back to the Back elevation, we will now need to constrain the object to the ref. planes drawn.
If you select the object, drag arrows will appear. (For anyone who has been on my course, IF IT IS BLUE, YOU CAN CHANGE/MANIPULATE IT)
Drag the top arrow to the top ref. plane, and lock it.
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Repeat this process on the bottom arrow.
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It is always a good idea to re-test your parameters.
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Change the heights, lengths, thicknesses etc until you are satisfied that this object works.

Save the family into your own library that you have created
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Congratulations, you have just drawn a Revit Family, with a basic formula.

























Loading a family into a project.
There are 2 ways you can insert a family into a project:
  1. Select File> Load from Library > Load Family
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  1. In the family file itself, you have an option to Load into Project
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This will automatically load the family file into the current project you are working on.
If however you have more than one project open, you will be prompted to load into a specific project.

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Select the project you want to load the family into. This feature has only been available since release 8 of Revit Building.



The Generic Model family that you have created is now a componet in the project browser of the specific project you have loaded it into.
If you click on component you will be able to place the object.
Place it anywhere on the screen and then select it.
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Notice the Options bar has changed.
These are selections and changes that are available on the family that you have selected.

Changing Properties of a Family in a Project
Once selected click on the properties icon. (image placeholder)
This will now bring up the element properties dialogue box, where changes will be made.
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The type Parameters are greyed out.
You will have to select the Edit/New button to change these.

A simple definition of Type Parameters & Instance Parameters

Type Parameter
A Type Parameter change would affect all parameters of the same type.
ie. If you had a chair type with legs that were a certain height. You would want to globally change all leg heights of the same type of chair, so that you do not have to change each chair individually.
Instance Parameter
An Instance Parameter change would affect the parameters of a single entity.
ie. If you wanted to change the fabric on one chair to yellow, but leave the others blue, that would have to be an instance parameter change.





In the exercise, we will change the type parameters of the family created.
Select Edit/New from the Element properties dialogue box.
You can now change all of the Constraints that you set up previously.
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Remember any changes made here are “Type based” so all families of that type will be changed.







Exercises to follow:

  • Nested Families

  • Sharing material Parameters

  • Switching visibility on & off of objects in families.

  • Revit Formulae: Including:

  • Array Formula

  • If Parameter

  • Nested If Parameter

  • Tan formulae

  • And many many more…….