CAD Export processes updated 2010-06-03 v1_0

This document outlines the processes of cross-platform collaboration between Revit and AutoCAD. Version 2010-06-03-1.0


Basically the steps involved in Exporting from Revit to CAD (and back) are as follows:


  • Creating reference in Revit (Discipline and type-specific, plan, section, elevation, Callout or detail) Naming the callout view name correctly.
  • Creating sheets in Revit (Setting up the details on the sheets in Revit)
  • Exporting Revit to CAD
  • Matching Revit output in CAD
  • Detailing in CAD
  • STRIP REFERENCING (For re-importing to Revit)
  • Re-Importing the enhanced information back into Revit.


NOTE:   Elements shown in RED are behaviors that need to be verified with each upgrade/update to Revit or CAD editing program. Each update can cause its own unique set of issues and should be tested on a case-by-case basis. This should probably be done with a single detail/sheet export/import from Revit to CAD before full export to CAD is assumed to be working correctly.


There are a number of cleanup VBA utilities that can be used to refine the Revit CAD Exports to align the Fonts, dimension styles, etc.


Exporting to CAD should only be attempted as a last resort as the process is time consuming and lengthy.


·         Create callouts/details in Revit
·         IMPORTANT: Rename the views in Revit to the view-naming protocol for the project. See the drafting view area for references to the view-naming conventions.
·         Create the sheets in Revit by dragging and organizing the details on the sheets. IMPORTANT: name the sheets per the sheet naming protocol for the project.
·         Assign base materials and callouts in the views on the sheets. This is the door/window/material callouts relevant to the type of view being exported. This is the "bare bones" basis for the AutoCAD information.
·         After bare-bones & Materials are assigned export the file(s) by using Revit Icon> Export> CAD Formats > DWG


Select the set to export (Or In session)
Select sheets/views to filter in the list. Sort by name to itemize everything by drawing type and its name
Set up CAD Layer naming (If not already set). Once set for a file Revit retains this information on a per file basis.


This may require selecting one of the read-only layer exports and resaving it under a different Name. Revit ADDS ALL LAYER NAMES from linked drawing files- to prevent this list from becoming too large we made it read only.


Browse to the export folder.


Strip everything off the 'tail' of the file name so the project number (and building identifier if necessary) is the only element left to use as a prefix. Revit will add a "-" after this prefix.


  • For standard CAD export (ONE-WAY to CAD) - Make sure the [ ] Xref views on sheets is unchecked. This places all elements with the sheet in one file.
  • For "STRIP REFERENCING"  (TO CAD and back into Revit) Make sure the [X] Xref views on sheets is checked.


NOTE:   If files and borders are to be x-refed for continuity- editing in CAD must be done to setup the xbdr files and other base files.


NOTE:   Renaming software can refine file names but will break x-ref naming associations. A preset for Bay Pines exists here:
               S:\Healthcare\3683a-00 VA Bay Pines\2.0 Drawings\2.4 Revit\4.0 Publish\4.3 DWG\4.3.1Renamer_Presets\03683a-00-VA_BAY_PINES-new.rnp
              
               *Mass-renaming of files should only be attempted certified users. If you have any questions or need someone else to clean up the DWG file names contact Ron Allen (Apsis0215@gmail.com) and we can go over the use of this software.



When exporting to CAD Revit creates PCP files containing pen weight information. As there are a number of customizations that occur in Revit between differently scaled views. This needs verification in a real-world test. Each new version of Revit/CAD can cause issues in exporting making it difficult to maintain visual fidelity between CAD and Revit drawings. It may be beneficial to use the exported PCP file for the sheet layout. Adjustments to the layer-export file may be necessary.

STRIP REFERENCING
One way to minimize the graphic impact of CAD & Revit sheets in a set is to create the bare-bones details and sheets in Revit, export the sheets to CAD, embellish the details in CAD via a 3rd file then link just the embellishments back into Revit for printing. We will call this strip referencing as each step in the information chain is stripped out from the previous one minimizing file sizes an the information therein.

On exporting from Revit [  ] Xref views on sheets should be selected to create separate drawing files to reference back into Revit.


Detailing in cad is intended to enhance the elements in those files using the elements as markers and locators when Revit resources are not available and CAD is the only resource available or is an only option.


Under no circumstances should the original location or base points in the drawing file be changed or the elements relocated in the file. The base points should ensure critical for re-referencing will match when the CAD files are brought back into Revit. This needs to be verified- there are some import issues when dealing with CAD in Revit Details. Real-world tests need to be run on a case-by-case basis to verify origin-to-origin match ups in Revit details.


Once the views/sheets have been exported to begin detailing in CAD:
  • Open an individual detail file
  • Save the file back out appending "-CAD" to the end of the file name. (IE "03683 - IDT3‑1G-301T - CASEWORK-CAD.DWG"
  • Move all the line work and hatching from the file away from the original location- this will be used for quick reference and eventually deleted.
  • XREF the original detail file (i.e. "03683-IDT3‑1G-301T-CASEWORK.DWG") back into the drawing as an overlay at 0,0,0.


Detail over the elements using:
  • The layers exported by Revit
  • The line types exported by Revit
  • The hatch patterns exported by Revit


Avoid the use of:
  • Masking regions
  • AEC Objects
  • Objects requiring proxy elements in earlier versions of AutoCAD. Proxy objects don't always translate. Keep it simple.
  • Match text styles, heights and dimension styles if possible


The "–CAD" version of the file should x-reference back into the CAD sheets at the same origin point in model space.


The -CAD version of the file should also reference back into the Revit drawing detail as origin-to-origin. This will bring in the additional detailing from CAD over the Revit detail. Because the views were exported as x-refs from Revit- the titles of the CAD files should match the view titles in Revit.

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