Trace a Spline in a Linked Dwg File and Some Recommended Reading

The scenario. You get a dwg file for overlay. The architect has drawn a beautiful sweeping curved  edge to their building, You link the dwg file into your model and see its a Spline.

Which presents two problems:

• You can't trace over it in Revit
• You can't set it out. And if you can't draw it, they can't build it

Fortunately, you can use the 'Flatten' command in Autocad to turn it to a polyline of arcs. By then exploding the polyline, you are left with a series of arcs that you can pick in Revit and also set out. The following short video demonstrates this



On another note and as a supplement to this, I recently came across
'The CAD Setter Out' blog by Paul Munford. For people who regularly have to clean up third party CAD files for use in Revit (or generally), this is comprehensive and highly useful resource. Its written generally from the CNC/Fabrication perspective, but is very pertinent reading to the designer. I'd recommend the following posts as a starter

From CAD to CAM, Cleaning up 2D DWG files for CNC.

How to optimize your AutoCAD DWG drawing files

Why Setter Outs aren’t (and don’t want to be) Designers.

I have created a mapping file for when you need to export

your views / sheets out to AutoCAD dwg files. The mapping file can be found in \MasterDocs\CAD\Revit\Waterman Library and is called WGPLC-exportlayers-dwg.txt

To do this go to --> file --> Export --> CAD Formats

Then go to Layer SettingsIf not already loaded you can Load and Browse to the file ..

As always if you find anything I have missed or got wrong please let me know.

As most of you already know ..... I do make mistakes.

Dwg into Revit recommendations by Autodesk.

a. Minimize the number of linked or imported DWG files.

b. Avoid importing unnecessary data like hatching or AutoCAD®-specific linework such as construction lines. Delete unnecessary parts and layers of the DWG file within AutoCAD and import only the cleaned, smaller DWG.

c. Avoid exploding the geometry imported from DWG files. The exploding operation within a Revit-based application can change a DWG from a single managed element to hundreds or thousands of additional elements depending on the number of entities in the imported DWG.

d. Only link essential DWG files into necessary views.

e. Switch off visibility of 2D AutoCAD DWGs in perpendicular views. A 2D AutoCAD file linked into a plan view will show as collinear lines in elevation, causing performance degradation.