This is a remake/design of http://www.thingiverse.com/thing:687502 because the dimensions were not correct for me. I've also made some improvements as well.
With this you can use the original nuts.
Take a look at this guy for more details for this setup: http://www.thingiverse.com/thing:349935
This is a work in progress as I still need to wire up the switches.
There is a left and right as well as a versions with a built in support.
Some design notes: 'measurement' ; 'part spec'
Carrage hollow nut ~12.7mm ; Nut set to 12.3mm
Carrage hollow nut depth 7.5mm ; Nut depth set to 7mm
z nut 12.45mm ; Nut hole set to 12.7mm
z rod 7.75mm ; Hole set to 8.6mm
Clamping hole ; 3.6 mm diam 3mm bolt
Clamping nut ; 6.1 mm edge-edge 3mm nut
MicroSwitch holes ; 1.8mm #2 wood screw
Noticed switches activate at different heights above the bracket. May need to move holes or bend lever to compensate.
Hope this helps.
Design files included
No longer WIP (it seems to work just fine). Also new pic.
After wiring it up and printing a few parts, I discovered I developed a significant z banding effect. Looking at a newer Robo3d R1+ model I found they did indeed remove the lever on the microswitch. This shortens the switch travel distance reducing the difference of the trigger distances between the two sides. After removing the lever on the microswitch the zbanding went away. I'm guessing it was caused by overcompensation or incorrect compensation from differing switch trigger height on both sides.
Also this is part of my slic3r start gcode relating to autolevel:
; Slicer start G-Code
G21 ;metric values
G90 ;absolute positioning
M82 ;set extruder to absolute mode
M107 ;start with the fan off
M190 S[first_layer_bed_temperature] ; wait for bed temperature to be reached
M104 S[first_layer_temperature] ; start heating extruder 1
T0 ; set the active extruder to 0
G28 X0 Y0 Z0 ; home all axes
G1 Z5 F8000 ; lift nozzle off the bed
M109 S[first_layer_temperature] ; set the extruder temp and wait
G28 X0 Y0 Z0 ; Home Z again in case there was filament on nozzle
M565 Z-0.85 ; set Z probe offset
G29 ; probe the bed
G0 Z3 ; Lift nozzle before lateral movement
G0 X110 Y120 ; Center nozzle on print area
; End of Slicer start G-Code
There's some extra movements that's to my own preference but basically:
G28 ; home
M565 Z-0.85 ; set Z probe offset,
G29 ; probe the bed
Printed in PLA. Supports may not be needed but I've designed a built in ring as a removable support.