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By Luke Davenport 

Issue:

You’ve got blocks, polylines, or normal lines in AutoCAD – like the profile above - that you want to bring quickly into an Inventor sketch and work some 3D magic on. But it’s not extruding! What are your options?

Solution:

Well these days there are tons of ways to bring your illustrious .dwg lines into the 21st century. Here’s a few general methods:

1. Use the old-school ‘Import DWG’ option – NOT the best choice!

But I want the import to be QUICK, and this method brings up the old-fashioned DWG/DXF File Wizard, which can take ages to run. And the dialog is confusing, and if the AutoCAD file is open during the import it fails….

(Just as an aside - This old-school import operation is slightly better if you perform it inside a 2D sketch – then you only get stripped-down options for importing 2D data).

2. Use the new-school DWG underlay option in Inventor 2016.

This is a fantastic method for bringing in large DWG layout files to use as reference, but is a little overkill if you simply need a couple of profiles to extrude, as it involves projecting the underlay into a new sketch after the import – a few more clicks. See this Cadline video for more info:

https://www.cadlinecommunity.co.uk/hc/en-us/articles/202788111-Inventor-2016-DWG-Underlay-Tip-n-Tricks-video

3. Simply copy and paste the lines/block straight from AutoCAD into an Inventor sketch.

This is where I want to focus. Getting the lines to extrude properly in Inventor in the minimum amount of time is the aim. Try the following steps for success:

a) First check that the profile can be hatched in AutoCAD. This will ensure that it is actually a closed profile, which is essential for extruding or revolving in Inventor. If it cannot be hatched then you can either try to clean it up in AutoCAD, or let the Inventor Sketch Doctor have a shot at it – see step (e) below.

Note: if it is an AutoCAD block, and you have issues with it - try exploding it first in AutoCAD and check whether it can be hatched before moving on to (b). If you want it to remain a block in Inventor, then use the ‘AutoCAD blocks to Inventor Blocks’ option in step (e) below.

b) Select the lines/block in ACAD. Hit Ctrl + C to copy to clipboard.

c) Start a new 2D sketch in Inventor, and hit Ctrl + V to paste.

d) Finish the sketch and try extruding it. Is it selectable as a closed profile?

e) If not, then you have a few options:

a). There’s a handy right click menu while you have the preview of the pasted geometry (before you drop it down in the sketch). Right click and hit ‘Paste Options’.

Select the two tick boxes shown below.

This might fix it. The reason for this is that lines that are joined in AutoCAD are not necessarily joined in Inventor - Inventor needs geometric constraints (coincident constraints) to be added between the end points of the lines.

b) If not, try using the Sketch Doctor to clean up any larger gaps between line endpoints.

Right click in the sketch and hit ‘Sketch Doctor’

Then you need to trawl through the Sketch Doctor (possibly multiple times) hitting ‘next’. Pay attention to any ‘Open Loops’ especially. Do this until all problems are fixed and you might get a result. If not then you have a more serious problem with the geometry to investigate in AutoCAD or Inventor, and you’re on your own I’m afraid!

I hope this helps!