Exploding DWG Files

 "Just don't explode DWG files" is good advice, that is immediately ignored because...reasons...

Setting that aside, now that we've exploded that DWG, now what. First, there is full explode versus partial explode. A full explode will recreate all the DWG elements into native Revit elements (assuming it is possible) but a partial explode will produce some native elements and some new DWG elements (blocks).

Reducing all DWG elements to equivalent elements in Revit is fraught with peril. Not all blocks in a DWG are created well. Explode one block that happens to have very large extents and your project will now have display/graphics issues. A Revit project might have one imported DWG but many times that number after partial exploding.

I recently encountered three project files that had +95k imported DWG files. These were the result of partial exploding less than 20 DWG files. As most people are aware, Revit won't create an element if it is too short (less than 1/32" long). A scary number of these DWG files were invisible, undetectable by eye in any view, because I believe their contents were too short to display. Many thousands were in just a few views. I used IDEATE Explorer to select, open the view they were in, if they were invisible then delete them.

It was time consuming; for some of them it was fastest to just delete the drafting view entirely because the view/detail wasn't going to be used on the project anyway. It was part of the everything and the kitchen sink approach in their template. Many of these details were derived from existing DWG based details created over many years to varying standards.

Back to Revit and exploded DWG elements...

Each line, arc, circle, etc. element is recreated and assigned to a new line style named for the layer it lived on in DWG. Similarly each text element is created using DWG info to define it as unique. Line and fill patterns are created this way as well. Ditto for dimension styles...and filled regions...

Once these exist in a project they are prone to being used by others because they are there. It is hard to ensure the standards a company has developed are used when this additional noise is present.

If we must explode a DWG let's not do so in our active project. Use an isolated file, based on our project standards (template). Once exploded, take the time to convert everything to our standard types. The completed drafting view can be added to our active project using Revit's Insert from File tool.

Also consider the time is takes to do this well...might be as long or longer than sketching over a detail DWG instead. If our detail item library is pretty good we'll be able to create a detail faster because we have components to represent the same kinds of things the DWG has in block form etc.

Don't sweep the DWG remnants under the rug...

Exploding CAD Data

Just say no! Friends don't let friends explode cad data! Any other words of wisdom?

If you have to...here is some text from the 2010 help file:

When you import a drawing into Revit, you are importing all the elements, such as blocks and external references (xrefs) from the drawing. (See Implications of Importing vs. Linking for Xrefs.) They are all contained inside a Revit element called an import symbol.

You can explode (disassemble) the import symbol into its next highest level elements: nested import symbols. This is a partial explode. A partial explode of an import symbol yields more import symbols, which, in turn, can be exploded into either elements or other import symbols. This is analogous to exploding in AutoCAD 2010 with nested xrefs and blocks. For example, you explode an xref into other xrefs and blocks. Those xrefs and blocks can, in turn, be exploded into more blocks and xrefs.

You can also explode the import symbol immediately into Revit text, curves, lines, and filled regions. This is a full explode.

NoteYou cannot explode linked files or an import symbol that would yield more than 10,000 elements.

Resulting partial explode import symbols can be exploded again by selecting them and clicking Partial Explode. You can continue to do this until all import symbols are converted to Revit Structure elements.