Since there is no forum topic for “calibration” (there should be) I’m posting this where it might be of help to a newbie.
Using a piece of paper or some such is not ideal for setting the z-axis gap.
For under $10 USD you can buy a set of metric feeler gauges that make gap setting easier and more accurate. Here is just an example:
amazon.com/25025-26-Blade-Ma … ges+metric
This makes it a snap to easily check the gap at (100,100,0) every day before printing. The gauges are also useful for accurate bed leveling.
While on the subject, the easiest fix for the z-axis stop nightmare is to simply turn the bolt around (to the way marked as “wrong” in the assembly instructions - go figure)! Because the bolt is narrow where it contacts the limit switch, just add a couple of M3 nuts tightened against each other at the tip of the bolt where it contacts the limit switch arm. Or if you have an M3 elastic stop nut, that works fine also if you turn it around so the widest part contacts the arm. So the problem is solved with the simple addition of two M3 nuts or one stop nut.
Great example of the excellent Vellerman support and desire to improve their product. For the cost of two M3 nuts and a minor change to the assembly instructions, 12,000 users would not have had to invent their own solutions. Some of the solutions are overcomplicated and require printing unnecessary new plastic parts.
Art