How to use AutoCAD *.dwg Files in Revit
Sometimes it will be necessary to bring 2D AutoCAD data into the Revit project environment. For example, as a background to trace over, or for importing survey information. When using 2D data from an external source, it is extremely important that the file you plan to import undergoes a clean-up process prior to importing.
There are two ways to bring an AutoCAD DWG file into Revit:
Import, or
Link
It is best practice to always “Link” files into Revit for the following reasons:
They are much easier to remove (if its brought in at the wrong scale, or is no longer required)
Linked files are connected to the external file, so if it is updated externally it can also be updated in Revit.
IMPORTANT:
Importing requires you to find the DWG file in the model, which can be difficult if it’s been imported at the wrong scale or turned off and set to “Current View Only”. Linked files can be simply removed from the Manage Links dialog without needing to know what view/s its located in.
It can also be worthwhile, if needing 3D DWG files in your project, to host them all in their own Revit Project file and to link that file in. This avoids any unwanted mess to enter the documentation model.
Linking a DWG file
Step by Step Guide:
Prior to linking, for each DWG file; Open the file in AutoCAD
Check for xrefs (externally referenced DWG files). If there are some, bind them to the drawing, using the Insert option to prevent redundant layers.
Run SETBYLAYER. This command removes any colour, linetype, or lineweight overrides from objects.
Run PURGE. This command removes any unused layers, linetypes, blocks, and styles.
Run OVERKILL. To get rid of redundant elements.
Freeze any layers you don’t need.
Ensure the extent of the model is relative to the File Origin and the extents of the model do not exceed Revit’s 20 mile sphere Floating Point limitations, as this will result in graphic glitches when Revit tries to display the AutoCAD file in Revit. A warning will typically be shown when importing a file that exceeds this limit.
Use SAVEAS to save a copy of the file in the Project’s “CAD Links” folder.
NOTE:
It’s important to retain a copy of the original, unedited version of the DWG, particularly if its been provided by a consultant, contractor or client.