How to Import CAD into Revit?

Importing or, more commonly, linking CAD files into Revit is a fundamental process for integrating existing design data, such as site plans, floor plans, or detailed drawings, into your Building Information Model. This tutorial will guide you through the recommended method of linking CAD files, which keeps your Revit project file size manageable and allows for easy updates if the original CAD file changes.

Introduction

Integrating CAD drawings into your Revit project can serve various purposes: using existing floor plans as a base for modeling, referencing site information for context, or incorporating specific details that might not be modeled directly in Revit. While the term "import" is often used generically, Revit offers two distinct methods: "Link CAD" and "Import CAD." Linking is generally preferred as it maintains a connection to the original CAD file, allowing for updates, whereas importing embeds the CAD data directly into your Revit project, increasing file size and losing the live link. This tutorial will focus on the more flexible "Link CAD" method.

Prerequisites

• Revit software is installed and running.
• A CAD file (e.g., DWG, DXF, DGN) ready for use.
• (Recommended) Ensure your CAD file is "clean" (purged of unnecessary layers, blocks, and linestyles), drawn to scale, and preferably has its origin (0,0,0) at a logical and known point.

Steps

1. Open Your Revit Project and Target View

1. Launch Revit and open the project where you intend to bring in the CAD file.
2. Navigate to the specific view where you want the CAD file to appear, such as a floor plan, site plan, or drafting view.

2. Access the "Link CAD" Tool

1. Go to the Insert tab on the Revit ribbon.
2. In the Link panel, click on the Link CAD button.

3. Browse for Your CAD File

1. An "Import/Link CAD Formats" dialog box will appear.
2. Navigate to the folder where your CAD file is stored.
3. Select the desired CAD file (e.g., a .dwg file).
4. Do not click "Open" yet. First, adjust the settings at the bottom of the dialog box.

4. Configure Link CAD Settings

Carefully review and adjust the following settings, as they are crucial for how the CAD file will appear and behave in your Revit project:

• Colors:
  • Preserve: Keeps the original colors from the CAD file.
  • Black & White: Converts all CAD colors to black and white lines. This is often preferred for clarity in Revit.
  • Invert: Inverts the colors (useful if your CAD has a black background and you want it on Revit's white background).
• Layers/Levels:
  • All: Imports all layers from the CAD file.
  • Visible: Imports only the layers that were visible in the CAD file's last saved state.
  • Specify: Allows you to choose which specific layers to import after clicking "Open." This is excellent for keeping your Revit model clean.
• Import Units:
  • Auto-Detect: Revit attempts to determine the units from the CAD file.
  • Custom Units (e.g., Millimeters, Meters, Inches, Feet): Manually select the units. This is critical for correct scaling. Always verify or manually set this to match the units the CAD file was drawn in. If your CAD was drawn in meters, select "Meters." Incorrect units will result in an incorrectly scaled CAD link.
• Positioning: This determines where the CAD file will be placed in your Revit project.
  • Auto - Center to Center: Revit centers the CAD file's extents to the center of your current Revit view. Good for quick, rough placement.
  • Auto - Origin to Origin: Aligns the CAD file's World Coordinate System (WCS) origin (0,0,0) with the Revit project's internal origin. Ideal if your CAD file is precisely located relative to a known origin.
  • Manual - Center: Allows you to manually place the CAD file by clicking its center point in your Revit view after clicking "Open."
  • Manual - Origin: Allows you to manually place the CAD file by clicking its origin point in your Revit view after clicking "Open."
• Place at:
  • Current View: Places the CAD file only in the active view.
  • Select Level: Places the CAD file on a specific level, making it visible in all views associated with that level. This is generally preferred for floor plans and site plans.
• Orient to View: If checked, the CAD file will rotate to align with the current view's orientation.

5. Execute the Link

1. After configuring all desired settings, click Open.
2. If you selected a "Manual" positioning option, you will need to click in your Revit view to place the CAD file. Otherwise, it will appear automatically based on your "Auto" positioning setting.
3. The CAD file will now appear in your Revit project.

6. Pin and Adjust (Optional)

1. The linked CAD file will typically be pinned by default to prevent accidental movement.
2. To move, rotate, or scale the CAD link, select it, then click the "Unpin" icon (or type UP) on the Modify panel.
3. Use the "Move" (MV) or "Rotate" (RO) tools to precisely position the CAD file.
4. Once the CAD file is correctly positioned, it is good practice to re-pin it to lock its position and prevent accidental changes.

7. Manage Linked CAD Files

1. To manage all linked CAD files in your project, go to the Insert tab > Manage Links button.
2. In the "Manage Links" dialog box, navigate to the CAD Formats tab.
3. Here you can:
   • Reload: Update the CAD link if the original file has been modified.
   • Unload: Temporarily hide the CAD link from all views without removing it from the project.
   • Remove: Permanently remove the CAD link from the Revit project.
   • Change Path: Update the file path if the original CAD file has been moved.

Conclusion:

Linking CAD files into Revit is a powerful way to leverage existing data and enhance your BIM workflow. By understanding the various settings, particularly "Import Units" and "Positioning," you can ensure your CAD data integrates seamlessly and accurately into your Revit project. Remember that linking is generally preferred over importing for better project performance and easier management of external data.

How to Create a Revit Family: A Step-by-Step Tutorial

Introduction

Creating custom families in Revit is a powerful way to add unique elements to your projects, whether they are furniture, custom components, or specific building elements not available in the default library. This tutorial guides you through the fundamental steps of creating a basic parametric Revit family from scratch, enabling you to build flexible and intelligent components for your models.

Prerequisites

• A working installation of Autodesk Revit.
• Basic familiarity with the Revit user interface (Ribbon, Properties Palette, Project Browser).
• An understanding of basic geometric shapes.

Steps

1. Start a New Family

   • Open Revit.
   • Go to the "File" tab in the Ribbon.
   • Select "New" > "Family".
   • In the "New Family - Select Template File" dialog, navigate to your desired template folder (e.g., Imperial or Metric libraries).
   • Choose the most appropriate family template. For a generic object, "Generic Model.rft" is a good starting point. For specific categories like furniture, windows, or doors, select their respective templates (e.g., "Furniture.rft"). The template you choose determines the family's initial behavior and available parameters.
   • Click "Open".

2. Understand the Family Editor Environment

   • You will be in the Family Editor, which resembles the project environment but features specialised tools for family creation.
   • You'll typically see pre-defined Reference Planes representing the origin and centerlines of your family in the "Ref. Level" (floor plan) view.
   • The "Create" tab in the Ribbon contains tools for creating geometry (Extrusions, Blends, Revolves, Sweeps, Void Forms).
   • The "Properties" palette will display the family's category and parameters.

3. Save Your Family

   • It's good practice to save your family immediately.
   • Go to the "File" tab > "Save As" > "Family".
   • Navigate to a suitable location on your computer.
   • Give your family a descriptive name (e.g., "MyCustomDesk.rfa").
   • Click "Save". Remember to save frequently as you work.

4. Establish Reference Planes and Parameters (For Flexibility)

   • Go to a Plan view (e.g., "Ref. Level") from the Project Browser.
   • From the "Create" tab > "Datum" panel, click "Reference Plane" (keyboard shortcut: RP).
   • Draw additional Reference Planes to define the boundaries or key features of your object (e.g., front, back, left, right edges of a desk). These planes will control the geometry's dimensions.
   • Use the "Dimension" (DI) tool to add dimensions between your Reference Planes. For example, add dimensions between the center Reference Plane and the left/right planes, and then make them equal using the EQ toggle. Add an overall dimension as well.
   • Select a dimension line. In the Ribbon, click "Create Parameter" (or select from the "Label" dropdown if a parameter already exists).
   • In the "Parameter Properties" dialog:
     • Name: Give it a clear name (e.g., "Length", "Width").
     • Parameter Type: Choose "Type" (the parameter value applies to all instances of this family type) or "Instance" (the parameter value can be different for each instance placed in the project). For most dimensions, "Type" is common.
     • Group Parameter Under: Select a logical group (e.g., "Dimensions").
   • Click "OK". Repeat this process for all desired dimensional parameters.

5. Create Basic Geometry (e.g., an Extrusion)

   • Go to the "Create" tab > "Forms" panel, and click "Extrusion".
   • Use the drawing tools (e.g., "Rectangle") to sketch the profile of your extrusion in the current plan view.
   • Crucial Step: After drawing the sketch, use the "Align" (AL) tool to align each sketch line to its corresponding Reference Plane. Click the small lock icon that appears after aligning to lock the sketch line to the Reference Plane. This ensures the geometry will move when the Reference Plane's dimension changes.
   • Once your sketch is complete and locked to the Reference Planes, click the green checkmark "Finish Edit Mode".
   • Go to an Elevation view (e.g., "Front" or "Left") from the Project Browser.
   • You'll see your extrusion. Adjust its height by dragging the top/bottom grips, or by entering "Extrusion Start" and "Extrusion End" values in the Properties palette.
   • Again, Crucial: Create a new Reference Plane for the top or bottom of your geometry (e.g., "Top of Desk").
   • Add a dimension between the "Ref. Level" and this new Reference Plane. Label this dimension with a new parameter (e.g., "Height").
   • Align the top/bottom of your extrusion to this new Reference Plane and lock it.

6. Test Your Family (Flex)

   • Go to the "Create" tab > "Properties" panel, and click "Family Types" (the blue box icon with an arrow).
   • In the "Family Types" dialog, locate the parameters you created (e.g., Length, Width, Height).
   • Change the values of these parameters and click "Apply".
   • Observe if your geometry updates correctly and maintains its constraints. If it doesn't, go back to the relevant view, check your alignments, and ensure all locks are engaged.
   • Click "OK" when you are satisfied with the flexibility.

7. Set Family Category and Other Parameters

   • In the "Create" tab > "Properties" panel, click "Family Category and Parameters".
   • From the "Family Category" dropdown, select the most appropriate category for your family (e.g., "Furniture" for a desk, "Windows" for a window). This is critical for how the family behaves in a project, how it schedules, and how it is filtered.
   • Review other parameters like "Part Type", "Cut with Voids When Loaded", etc., and adjust as needed for your specific family.
   • Click "OK".

8. Load into a Project and Test

   • If you don't have a project open, open one or start a new default project.
   • In the Family Editor, go to the "Create" tab > "Family Editor" panel, and click "Load into Project" (or "Load into Project and Close" if you're done editing).
   • Revit will switch to your open project.
   • Navigate to a suitable view (e.g., a floor plan or 3D view).
   • Place an instance of your family.
   • Select the placed family instance in the project.
   • In the Properties palette, you can modify any "Instance" parameters you created.
   • To modify "Type" parameters, click "Edit Type" in the Properties palette.
   • Observe how your family behaves and appears in the project environment. If you need to make further edits, select the family instance and click "Edit Family" in the Ribbon.

Conclusion

You have now completed the fundamental steps to create a basic parametric Revit family. This process of creating Reference Planes, adding parameters, creating geometry, locking it to the planes, and testing its flexibility forms the core of all family creation. With these skills, you can begin to create more complex and intelligent components to enhance your Revit projects.