It is a good idea to watch from the side and the top when the CubeX prints the first layer. Looking at the first layer print lines you can quickly see if your z-gap setting is ok.
The first layer should be a little smushed onto the print bed so you get good adhesion and no gaps between print lines. A z-gap of just under 0.1mm should do that. Some use just a sheet of paper to check the z-gap.
If you print with ABS, you want your z-gap a little tighter, close to 0.05mm.
See the illustrations below: (another CubeX user found them somewhere on the Cubify website, - thanks J. Andre!)
- Select the "Home" button. This will move the print jet behind the print bed so you can do step three.
- Make sure the jets don't have any (not even a tiny piece at the tip) of filament left stuck on them otherwise it can affect your z-gap measurement.
- Hit the "z-gap" menu button and check or adjust the z-gap with the up/down button.
- Then print.