Friday, July 19, 2013

Working with DWG files in Revit

It might not seem obvious, but it is very important clean up DWG files before importing or linking into AutoCAD. Revit is not AutoCAD and it is important to note that Revit will not behave like AutoCAD. So we need to take this into account when working with DWG files. Spending a few minutes cleaning up a DWG file before importing or linking that file can prevent real problems from occurring down the road.

Here are some items to consider when working with DWG files in AutoCAD.

1.     Be aware how far the CAD geometry is from 0,0,0. Different versions of Revit get squirrelly if the geometry is either greater than 2 miles or 20 miles from 0,0,0 in AutoCAD. While you are checking this, look for scratch or unnecessary geometry that might just be hanging out somewhere. If you don’t need it, get rid of it. Use Zoom extents in AutoCAD to see the extents of the geometry.

2.     Review the layers in AutoCAD. Make sure you are aware of what is on/off or frozen / thawed. If there is geometry on layers that are hidden or frozen, consider deleting that geometry and purging the layers. Put the DWG file on as much of a diet as you can.

3.     Be aware of blocks that are using in the DWG. If you are experiencing display issues in Revit, the issue might be with the block. It’s only been a problem for me a couple of times and exploding the blocks in AutoCAD corrected the issue. The simpler the CAD file, meaning few blocks, xrefs, etc that are in the DWG file, the better.

4.     Put the DWG on a Diet. Purge ANY and ALL unused layers, blocks, styles, etc from the DWG. The less Revit has to track the better.

5.     Verify your units of the DWG file before importing.

6.     Watch out for really small geometry. Revit will generate a warnings for lines that are smaller 1/32” or 0.75mm.

7.     Consider linking or importing DWG files onto a separate workset.

8.     If you only need to see a DWG in a single view, always use the Link to Current View Only option.

9.     I think this goes without saying, but worth repeating. To everything possible to avoid exploding imported DWG files.

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