autodesk revit families: the basicsaucache.autodesk.com/au2012/sessionsfiles/6893/4625... · web...

Autodesk® Revit® Families: The Basics

Frank Sheiakh – Bimit AB

AB6893-L

Learning ObjectivesAt the end of this class, you will be able to:

Know the difference between predefined templates

Know how the different 3D modeling tools work

Structure a family from the ground up

Build a basic family the right way.

About the SpeakerFrank has been working with Revit since Autodesk bought it back in 2002. As a CAD consultant he has a long experience with AutoCAD, AutoCAD Architecture and AutoCAD MEP and has been adopting all these packages to both local standards in Sweden and customer specific changes to the products.

As a Revit consultant he has been vital to several Architectural Revit projects but no project as prestigious as the NKS project. http://www.nyakarolinskasolna.se/en/

[email protected]

http://www.nyakarolinskasolna.se/en/


IntroductionAutodesk® Revit® provides us with a powerful toolbox for parametric modeling. But with great power comes great responsibilities. Too many times do I see content made without proper knowledge of the basic dos and don’ts? With the Autodesk® Revit® family editor and mass modeler you can model anything (yes anything). So the question becomes not IF I can model whatever I want to, but SHOULD I model it?

Parametric or Not?Well this question is really if we should add more parametrics to our family. Everything in Autodesk® Revit® IS already parametric, we just choose if we would like to control that with named parameters. A rule of thumb is that when you have 3-5 different variations of the same family it might be a good idea to make it parametric. An office chair for instance is not suitable for parametrics since it is more or less the same size regardless of maker and it will always fit, it is also very complex modeling wise. A door on the other hand consists of many similar variations and is fairly easy to make parametric. In the end it’s all up to you as a content builder to decide if it is worth the extra effort to make something parametric.

Templates

Family CategoriesThere are a lot of different family categories. Choosing the right one is crucial to your success as a contentbuilder. Besides your obvious categories there are a couple of different ones that might be worth pointing out. The Mass category for instance, you may not change a family to a mass nor can you change a mass family into something else. If you change your category to a “Profile” you will not be able to go back. You change the category by entering this dialog box:

Different categories come with different predefined parameters that are hardcoded into the family itself. If we compare a generic model family to a door family we see that the door has several extra parameters.

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Hosted FamiliesA Revit Family can be hosted to a number of different things:

Facebased Floorbased Wallbased Linebased Roofbased Ceilingbased Patternbased

Be sure that you know what the intentions are for the family because once it’s hosted you cannot remove that link.

If you make a shelf your first instinct can be that it should be wallbased, well think again. Let’s say you make the shelf wallbased, later on in the process you remove that wall. Well that will delete the shelf also, which might not be what you want?

The same goes with all hosted families. Don’t make families hosted unless you absolutely have to. Some things should of course be hosted, like doors. Windows should probably be wallhosted also, but what happens if you need a skylight? Then you need to redo the entire family as either a roofbased component or maybe a facebased one. The facebased families will NOT be deleted if the host is deleted.

Predefined TemplatesRevit ships with a lot of predefined templates. These templates sometimes contain a lot of information, information that you might not want.

Note that some of the elements that are predefined in a template won’t be able to be deleted.

Most experienced contentbuilders start out with a generic model template. If you start with one of those you get total control of what the family contains. Remember that when you change category from generic model to anything else Autodesk® Revit® will add some new hard coded parameters.

This is the different generic model templates:

Metric Generic Model Adaptive.rft Metric Generic Model ceiling based.rft Metric Generic Model face based.rft Metric Generic Model floor based.rft Metric Generic Model line based.rft Metric Generic Model Pattern Based.rft Metric Generic Model roof based.rft Metric Generic Model wall based.rft Metric Generic Model.rft

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All templates that are hosted (based) contains that specific object in the template. A Floorbased family has a floor slab to model around/in/on etc. There is no way of “adding” a host to a non-hosted template. You can however “nest” a non-hosted family into a hosted one.

3D Modeling tools

SolidsThe Autodesk® Revit® family editor (this is the interface you see whenever you open a family or create a new one from a family template) contains 5 tools to create solids and 5 tools for voids.

Extrusion Blend Revolve Sweep Swept Blend Voids

Exercise 1: ExtrusionThis is by far the most common tool of all solids. You start by drawing a 2D profile (closed loop) and then give that profile a depth.

1. Start a new family based on the “Metric Generic Model.rft”.

2. Click “Extrusion” on the “Create” –tab.

3. This will bring you into sketchmode. Sketchmode is easily detected by the green color of the ribbon background.

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Sketchmode

Normal mode

4. Once you’re in sketchmode you have to make a decision to close it (2 times on the escape button doesn’t quit the function). You either have to accept the sketch by clicking “Finish Sketch Mode” or decline the sketch by clicking “Cancel Sketch Mode”.

5. In sketchmode you can start using the “Draw” tools. You can draw anything as long as the lines form a closed loop and don’t intersect each other.

6. In the properties panel you have the possibility to change the values of the extrusion. You can for instance set where the extrusion should start and end based on the workplane you are using.

7. These values can be both positive and negative.

8. Once your sketch is finished you click “Finish Sketch mode”.

9. Notice that the properties are still there for you to change.

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10. If you would like to edit the sketch you just need to select it and click “Edit Extrusion”.

Exercise 2: SweepThis tool extrudes a profile along a path either in 2D or 3D.

1. Start a new family based on the “Metric Generic Model.rft”.2. Click the “Sweep” button.3. This tool allows you to pick a

path or sketch a path; we’ll start with the sketch tool. Click “Sketch Path”.

4. Your first line will define a workplane perpendicular to itself. This means that if you have a line that follow any of the predefined planes you should start with that, otherwise it might be hard to sketch properly.

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5. Continue to draw the rest of your path. We will use this sweep in our next exercise.

6. Finish Edit Mode.7. This will bring you back to the original tool.

8. If you have a profile family defined in the project you can select it now. We will draw our own, click “Edit Profile”.

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9. Autodesk® Revit® tells us that the view we’re in is not suitable for the sketch. Choose one of the suggested views.

10. The Red dot tells us where the sketchline is located. Use the drawtools to lay out your profile, make it look like a silhouette of a house. NOTE! Profiles are not allowed to double back on itself.

11. Finish Edit Mode.12. Then click “Finish Edit Mode” for the entire solid.13. The result:

14. We will now attempt to sweep something in 3D.15. Revit cannot sketch in 3D which means that we need some sort of help

object, either we create it or we import it.16. In this case there’s our “house”.17. We’re going to add a sweep to the roof.18. Click “Sweep”.19. Click “Pick path”

20. Now select the edges of the roof, use orbit to turn the building. Remember that the first line sets the workplane.

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21. Finish Edit Mode.22. Click Edit Profile.23. If you’re in a 3D view Revit will not

prompt you for a view. You can however switch to a better view. I’m using a “Front” view.

24. Draw your profile.

25. Finish Edit Mode.26. Finish Edit Mode for the Solid.

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Family Structuring

Which parameters do we need?Regardless if we choose to make a family parametric (geometry) or not we need to think of what the “I” in bim means for this family. Do we need to add anything that doesn’t drive geometry?

In this exercise we are going to make a Bed.

So the first question is, which parameters do we need?

“Width”, “Height” and “Depth” is probably something we need to have.

In our example we’ll add these parameters:

Width Depth Height Mattress Height Mattress Material Leg Material

Instance or Type Parameters?After we know which parameters to use we need to figure out if they should be Instance or Type parameters.

We’ll use Type parameters in our example.

Naming conventionYou can use different naming conventions and maybe there is one in place in your company. I’ve found this one to work nicely.

Start all major words in your parameters with a capital letter, “Length”, “Frame Width” “ etc. This will make the parameter easy to read.

Always start with the function of the parameter first. “Frame Width”, NOT “Width Frame”, this will group all frame parameters together.

Do NOT use abbreviations that only you understand, it’s better to spell the parameter in plain text.

Do NOT use mathematical expressions in your parameter names, NO minus signs.

Reference planes/ Work Planes/ Reference LinesFor us to be structured, for better overview and to use all functions of the family builder we need to start out by adding Referenceplanes/Workplanes/Referencelines.

Refrenceplanes can be used as a workplane ( a place to host your geometry) íf you name it.

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Be sure to name all Referenceplanes as soon as you place them, otherwise they don’t show up in selection lists.

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Exercise 3: Basic Parametric ModelingThis exercise will feature a bed:

At the end of the exercise this bed will have parametric dimensions and be able to change materials.

1. Start a new family based on the “Metric Generic Model.rft”.2. Change the family category to “Furniture”.

3. Draw 4 referenceplanes in plan view, name them Left, Right, Front and Back and give them “Is reference” respectively.

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4. Dimension the ref. planes and click the “EQ” text.

5. Dimension the Left and Right ref. planes and then the Front and Back planes. Use the Label option to connect these two dimensions to the Width and Depth parameters.

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6. Since we don’t have them defined yet we need to add them now. Click “Add parameter” in the label dropdown.

7. It will bring you into this dialog box:

8. Create the “Width”, “Depth”, “Height” and “Mattress Height” accordingly.9. Switch to the Front Elevation.10. Add the “Top” and “Bottom of Bed” ref. planes.

11. Dimension them and add the “Height” and “Mattress Height” parameter.

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12. Switch back to plan view and add 2 reference planes for the front and back legs. They should not have any reference. Dimension and lock them 200 mm (≈8”) from the Back/Front planes. Name the back plane “Back Legs” and we will NOT name the front legs plane on purpose.

13. Flex the model.14. A good way to flex the

model is to make types.15. Click “Family types”.

16. Clic k

”New” and name it properly.

17. Make 2 new types with different dimensions and switch between them.I’m using the following measurements:Type 1: Type 2:

Width=900 mm (≈2’ – 11 ½”) Width=1200 mm (≈3’ – 11”)Depth=2000 mm (≈6’ – 6 ½”) Depth=2100 mm (≈6’ – 10 ½”)Height=600 mm (≈1’ – 11 ½”) Height=400 mm (≈1’ – 3 ½”)Mattress Height=200 mm (≈8”) Mattress Height=100 mm (≈4”)

18. We will now add 3D geometry. Switch back to Plan view.

19. On the “Create” tab and “Forms” click “Extrusion”.

20. “Set” the workplane to “Bottom of Bed”, this will ensure that we start the extrusion in the right place.

21. Draw a rectangle following the outer reference planes, make sure that you snap to the corners of the reference

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plane box. Before you do anything else, make sure that you tick the four padlocks. If you forget this or press escape a little too fast you can use the align tool to constrain the lines again. Accept the sketch when you are done.

22. Switch to an elevation view. Since all extrusions get a default height of 250 mm we need to constrain the extrusion to our Top reference plane, we do this either by aligning it with the align tool or we select it and drag the blue grip to the reference plane, don’t forget to tick the padlock afterwards.

23. With the extrusion still selected, click “Visibility Settings”.

24. This dialog box gives us the possibility to define when this extrusion is visible.

25. This extrusion should have all boxes ticked.

26. Flex the model.27. We will now add a set of legs.28. This will be 2 U-shaped legs.29. Switch to Front view.30. Select the leg and the bed extrusions. Temporarily hide them.

31. Start the Sweep command.32. Set the workplane to “Back

Legs”.33. Click “Sketch Path”

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34. Draw your path, make sure you snap to the intersections. I’m using a radius of 100 mm (≈4”).

35. Finish the edit sketch mode.36. Click “Edit Profile”.

37. The workplane for the profile is defined by my first sketch line. In my case Revit wants us to switch to a view perpendicular to that (the predefined selection is often the best one).

38. Click “Open View”

39. As you can see the red dot that represents the path is placed correctly. If we had failed to set the right workplane this result might be different.

40. Continue to draw the profile you want, mine has a 25 mm (≈1”) radius.

41. Finish the entire sweep when you are done.

42. Do the same for the Front Legs. Note that since we didn’t name the reference plane, we cannot use it as a workplane. Correct that and continue.

43. While the legs are still selected, change the visibility settings so that the legs don’t show in “Plan”.

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44. Start a new project. Load the family into the project and place your types. Make sure to test all views, Plan, 3D, Section and Elevation.

45. Go back to the family and fix any problems.46. We will now add some 2D graphics to make this rectangle look more like a bed in

plan view.47. Switch to a plan view.48. Set the reference plane to “Top”.49. Temporarily hide all 3D objects.50. Move to the “Annotate”-tab

and click “Symbolic line” under the “Detail” group.

51. We are now in 2D sketch mode.

52. In the subcategory dropdown menu we can select if this line should be in a subcategory.

53. In this exercise we use the one called furniture.

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54. We will add a horizontal line 500 mm (≈1’ – 7 ½”) from the back reference plane. And a diagonal line from the corner of that line to the bottom corner of the bed.

55. Just like reference planes, 2D graphics get a “Weak Reference” as default. Select the two lines and change them to “Not a reference”.

56. While the 2 lines are selected don’t forget to set visibility.

57. Flex the model.58. Load it into the project and overwrite

parameters.59. Switch to a 3D view in the family.60. Select the mattress.61. Find the “Material”-field.62. Click the parameter button next to it.

63. Add a parameter named “Mattress Material”.

64. In properties the field turns grey and the button gets 2 lines in it indicating that the field is driven by a parameter.

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65. Select the legs and give them a parameter named “Leg Material”.66. Go to the Family types dialog box and add materials to the types. Click the button to

the right of the “Value” field:

67. Load and select the material you want to use:

68. Do this for both the mattress material and the legs material. 69. Load the family into the project and switch to “Visual Style: Ray Trace”.

70. Finished

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autodesk revit families: the basicsaucache.autodesk.com/au2012/sessionsfiles/6893/4625... · web...

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