Can easily micro-adjust the height of the nozzle off the bed by turning the adjustment knob 1/8 to 1/4 of a turn. Is great when changing filaments and having to reset the Z offset. After you have used it a while you will get a feeling for just how far to turn the adjustment. Move it slightly, hit "Z Home" and see the results.
Lay the "Z - Limit switch adjust adjustment holder" on the back with the nut slots and the mounting screw indents up.
Reasoning behind build:
I always had difficulty adjusting the Z-end stop limit switch. It was hard to get it positioned perfectly, then try and hold it in place while tighten up the mounting clamp. The switch moved to easily up and down and all around the 8 mm polished rod. It was to easily bumped out of position. Wanted something that I could easily mirco-adjust, and was repeatable.
(1) 4 inch 6-32 machine screw (mine actually came off an old toogle bolt)
(4) 6-32 nuts
(2) small washers
(1) small 3/4 long spring
The first one I made was for a Migbot i3 (manufactured by Electron). I made another later for a HIC - Mendel i3. The HIC -Mendel version needed a slightly different "Spacer Block". The spacer block is necessary to keep the limit switch mounting bracket from spinning around on the 8 mm polished rod.
Since it uses the stepper motor mount bolts to hold it in place, you may have to use slightly longer metric bolts there.