Illustrator doesn't do very well with writing dxf files. It reads them just fine, tho.
Won't Robo Master Pro read any other file types like EPS? I'd use that to start with.
Second, and I only know this because I specialize in 3d CG, while my Fiance specializes in vector work, is that Illustrator uses a different system units than most other programs. It actually uses millimeters while most other programs in the US use inches. So when you save a dxf from illustrator, and open it in another program it will be 2540% too large.
I'm not talking about your scale or working units. That's a completely different thing.
So like I said, export as an EPS file and see if you can work with that.
Better yet, Graphtec has a plugin for use with Illustrator so that you can cut directly from Illustrator.