Hi Chris, above you wrote "IGS" file conversion - did you mean STL conversion?

Normally to get a clean STL file generated, you should have just a single solid object that you are exporting.

In your case you don't have that - instead your model is made up of 11 different individual objects, note the readout after a "Select All" here:



Also if you look in the scene browser, you can see that you have at least one object that is an open surface instead of a solid:




You can use the scene browser to select that open surface object by clicking on the text for "Surface" there, that identifies this part as the one that is not a solid:



Then running the script from here which selects naked edges, identifies these edges as being open and not attached to anything else:




So to remedy that, select that crossbar piece and then run the Construct > Planar command, which will fill in the open end with a trimmed planar surface and seal it off.

Once you have done that, you will then have 11 solids in the file.

It may possibly work at that point, for some cases it may be ok to have multiple solids within a single STL file but really the main original intent for an STL file is that it should contain just 1 single solid in it and not multiple ones.

So then you would probably want to use boolean union to combine those multiple solids together where they are touching so you only have just 1 solid. That's what I've done with the attached updated 3DM file.

The attached file is now all ready to be exported to a good STL file.

- Michael