Subtract an Imported Model

[calebUYG4X]

I imported a .dwg file into my current project as an XREF.  I then inserted it so it is no longer shown as an XREF but as part of the main drawing.

I am trying to subtract the imported 3D object from an object in the current project.  When I attempt to do this using the subtract tool, it does not work.  I am guessing it has something to do with the way I imported the object?

Does anyone have any ideas as to why I cannot subtract the imported object from the object in the main drawing?

If needed I can attach the DWG files here.

Thanks.

[Patchy]

If you save it to version 2014 or older I'll take a look.

[calebUYG4X]

Sure thing.  See attached.

I also attached the newest version incase others might like that.

"Screw" is the dwg I imported (if needed), and "TC Gear" is the main project (the one in which I am trying to subtract).

And here is a video of what I am trying to do and what happens:

https://youtu.be/e6mSvr7N958 

Thanks again.

P.S. Sorry for the disorganization and the bad design practices, I'm still learning. 

[calebUYG4X]

And here is the "Screw" file in 2013 format.  It would only let me attach 3 files per post.

[Patchy · Accepted solution]

The problem:

The screw is a block, you need to explode it, then you will see 2 parts. Use UNION command to combine the core of the screw and the threads.

Then you can subtract the screw from the gear.

[calebUYG4X]

Yes, that makes sense.  Thanks.