Tips on inserting CAD Details to Revit

by | Feb 10, 2018 | CAD, Knowledge Base | 0 comments

What do you do when you have built up a whole library of standard details in AutoCAD and now you’ve switched to Revit? Do you continue to use AutoCAD and print out sheets from within it? In a situation where you’ve not built up your Revit Details Library, Importing CAD in Revit may be a good starting point. Eventually it is a good idea to do these details in Revit itself using Revit lines and families.  To get the best results and save you time, you need to do little setup before you import your DWG files. This post focuses on this process and provides you with some useful tips to make the whole process smooth and maintain graphic accuracy to give you the best results. Video at the end of this article demonstrates this whole process.

Inserting CAD Details

Typical Details are created in “Drafting Views” as 2D elements. These details can easily be exchanged between projects. So you only need to create them once and re-use them. You could even create a separate Project file in Revit and use this as your Details Library.Before you import DWG file you’ll need to follow a few steps.

Separate out a Single Detail

Your source DWG file may contain multiple details in Model Space. Separate these out as individual DWG files in a separate folder. You could use “WBLOCK” command to do this. This process provides multiple benefits. One important benefit is that your original file remains intact. In addition, when you import individual details in to Revit Drafting View, each of these Drafting Views relates to one detail. Name each drafting view similar to the detail name you’re importing. Naming each of these views sensibly saves time in the long run as you would be able to quickly identify them right in the project browser without opening each one.

Clean up the separated DWG

Your original files may contain unwanted layer of elements on hidden layers. Make sure you remove these so you have a clean DWG to import.

Line Weight Mapping

Few Settings in Revit can save you a lot of time. These settings can maintain “Line Weights” to match your AutoCAD CTB file. Similarly, Revit fonts can be mapped to those in Revit. If you use “Line Weight” settings to correspond to a layer, Revit will maintain the “Line Weights”. However, if you use a “CTB”, where a color corresponds to a pen weight, you can easily create a custom mapping in Revit. Make sure you save the custom settings as a separate file. and not over-write an existing one.

Font Mapping

Revit uses fonts installed in your computer. AutoCAD can use these as well and in addition, it uses SHX fonts, typically present in old versions of AutoCAD. You have two options:

  • The simplest, is to change SHX fonts to Windows fonts in the DWG file itself. This can be time consuming if you have a large number of files.
  • The other method is to edit “shxfontmap.txt” file. This file is located as indicated below:

<“%APPDATA%\Autodesk\Revit\<product name and release>”

Simply edit this in Notepad. Make sure you use the following format to edit this.

<filename.shx [TAB]fontname>

Where

  • Filename.shx is the SHX font in your AutoCAD file.
  • [TAB] is the TAB key on your keyboard
  • fontname is the font you want to use and the one that replaces SHX font.

Import CAD to Revit

Before you insert your CAD file, you will need to customize DWG import settings in Revit.

DWG Import Settings

Switch to Insert panel on Revit ribbon menu, and click on the small arrow as shown in the image below. This opens up DWG import settings dialog box. If the line weight settings do not match your office standards, you’ll need to modify the settings here. Before you do this, save the current file as another file so as not to over wright any of the existing standard ones. Just match AutoCAD color to the line weight you want and save.

Revit Import CAD Settings

You’re nearly done. Create a Drafting View and name it similar to the DWG detail name and the View Scale to say 3”=1’. Now insert the DWG. Make a few changes here as indicated in the image below.
Click OK. The insert DWG file maintains line weights and font settings. Just note that you may still have a few issues to deal with.

Font heights may be incorrect, if they’ve not been set correctly in AutoCAD. The other issue may be that some of the hatch patterns may look as solids. You’ll need to adjust the Hatch scale factor in your DWG file. Similarly, Check out if text height are correct. Use the formula below to determine if the text height is correct:

Desired Text height on Paper> X <Print Scale

For example, if you want details to be printed at 3”=1’ and the standard text height you want is 3/32”, then your calculation will be as below:

  • 3”=1’ = 3”=12” = 1” = 4″
  • 3/32 = 0.09375
  • Text Height in DWG will be = 0.09375 X 4 = 0.375”

If you have these settings, Inserting DWG can be accurate. Nothing further needs to be done. That’s it.

The video below demonstrates the process.

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