I use Eagle with the gcode plugin - a (ULP) for Eagle, and a SainSmart 3018 which is just like the one you stated above. I use Candle to control the 3018 with a 20 degree V bit and this is my result. A PCB that was made from Mr. Carlson's LAB Schematic. As you can see it creates a one sided board for SMD parts. The main chip is a 20 tab IC on the top. LM3914V SMD. I did this after adding probes so I could use height map. I set the gcode to Z-0.2mm deep. Also, I had not added in homing switches yet. You can tell as I moved the board prior to drilling so I had to by hand realign. Holes are slightly off but usable. I did make a second one with the holes dead center. That is what I used to build the Capacitor Checker. I just never trashed this board so I had it as an example of what one can do. Hope this helps, but it takes days not hours of fiddling to get these results. I can be done and once done for under $200 you can have a great working system. It cost me over 200 hours of my time. And I am talking working time. Not the sitting around time waiting for a board to get height mapped and cut. Now from gcode to made board is about 30 min if I decide to do a detailed height map, otherwise half that time.
CJD