RepRap Prusa i3 bed auto-level

When going down, the extruder will touch the bed, and the axis will keep on that heigt, since the Z_EndStopMount pieces are not glued to the axis, they will continue going down and the circuit will get opened, then, z-min is triggered.

Demo video:
https://www.youtube.com/watch?v=AOHPTKWP9wo
http://youtu.be/PSwfhPHeCR4

Download the model:
http://www.thingiverse.com/thing:273805
(The Prusa_i3_X_End_Motor.stl is copied from
http://www.thingiverse.com/thing:39889/#files)

* Parts:
* AutoLevel_Z_EndStopMount.stl x1
* LM8UU x1
* Screws M3-15mm x1
* Screws M3-5mm x1
* Screws M2-8mm x2
* Nut M3 x1
* Nut M5 x1

Just like the "X End motor mount ", Use a M5 nut to pull up/down the end-stop-mount. But need use a M3-5mm screw to fix the M5 nut with it.

M3-15mm and the M3 nut is used to grip the LM8UU in the center clamp.

Directly use the original Z End-Stop micro switch as the detect switch shows in the figure.

Adjust the