Many corruptions within Revit projects can be avoided by the proper workflow. Importing CAD files is something we are all used to and has become a force of habit. Revit, however, does not function properly when CAD files are inserted. Ideally, you wouldn’t have any CAD files within the main Revit project, however, it’s understandable that this isn’t always avoidable.
Before using CAD files within your Revit project, use this 3-step tip to clean them up as best as possible: https://autode.sk/2QwObTk
Some workarounds to improve performance if you need to have use CAD files are:
- LINK files into the project.
- If they are temporarily used, it’s easier to see where they are located and easy to unload them to remove them from your project. Imported CAD files are much harder to find and more often than not, they require scripting to remove.
- Unload/remove unneeded CAD files. CAD files add considerable bloat to Revit. IF CAD files are visible in the view, the view navigation performance is affected.
- It is advisable that CAD file should be cleaned up (especially civil files), purged, audited, PROXYGRAPHICS set to 1.
- Create a CONTAINER file.
- When collaborating, link your CAD files into their own Revit file, and position them accordingly and in appropriate coordinates. You can now link that Revit file into your project. This means you have control over where it’s linked into, filter it, unload/reload it, etc.
- When needing them as a REFERENCE.
- Avoid importing CAD and Explode CAD in project or families. Always use an interim file to convert CAD linework into Revit lines. In a new project or family Import the CAD, Explode and then remap the lines, patterns to match your company standards or OTB types and styles. Copy the cleaned-up version into your actual project or family. Avoid CAD files within a family.
Some extra tips here:
- 13 Tips to Understand Line Weights in Revit: https://bit.ly/2tGUJGk
- Graphics Issues after Linking or Importing CAD: https://autode.sk/2SjeD48
- CAD Files Best Practices: https://autode.sk/2GcWrol
When you export from Revit into CAD, there are 3 options of how to export the layers.
The explanation given by Autodesk for these options are as follows:
Export category properties BYLAYER and overrides BYENTITY
A Revit element with view-specific graphic overrides will retain those overrides in the CAD application but will reside on the same CAD layer as other entities in the same Revit category.
Export all properties BYLAYER, but do not export overrides
View-specific graphic overrides will be ignored in the CAD application. Any exported Revit element will reside on the same CAD layer as other entities in the same Revit category. By forcing all entities to display the visual properties defined by their layer, this option results in a lower number of layers and provides by-layer control over the exported DWG/DWF file.
Export all properties BYLAYER, and create new layers for overrides
A Revit element with view-specific graphics will be placed on its own CAD layer. This option provides by-layer control over the exported DWG/DXF file and preserves graphical intent. However, it increases the number of layers in the exported DWG file.
Note: If you are exporting a view that contains a linked project and the RVT Link Display Settings dialogue (Basics tab) for the link is set to By Host View, then the link is treated as an override. To ensure that colours and other graphic display settings are preserved in the exported file, select "Export all properties BYLAYER, but do not export overrides."
Source and more info here: https://autode.sk/2EPfTUK
More sources for Revit-To-CAD workflows here: