Robo3D Z-Limit Switch Relocation

thingiverse

I've been having nothing but problems with the auto-level and z-limit switches since I first plugged in my Robo3D two weeks ago. The very first movement it made was to home the z-axis, but when it tried this simple task, the wiring of one of the switches failed, causing the nut that raises everything to fall out of the z axis bracket and wrap around the rest of the limit switches above. I took a model of the extruder carriage - which looks eerily similar to leonmf's work from http://www.thingiverse.com/thing:192639 - and modified it to only be about 10mm thick by adjusting the dimensions on a model of my Robo3D. I also added a leg with a foot that can take a #8 machine screw, which may need some heat or a bit to keep the ABS around the screw hole from cracking. I unplugged the wires to the existing z-limit switches and connected them to an Omron V-156-1C25 that I had lying around in the spare components bin. After making the connection, I placed the switch into the limit switch holder. Then I printed out the x-carriage-z-stop model, installed it on the x-axis rails, put the limit switch and holder under the foot of the x-carriage-z-stop, and adjusted everything so that the arm of the switch lined up with the hole in the foot past the other switch underneath. This way, the mechanical advantage would work to our benefit and the light weight of the x-axis and extruder-carriage could trip these heavier duty switches without needing any additional weight. There was a small hole in the bottom of the limit switch model that didn't print well at all, so I applied some Elmer's Multi-Purpose Spray Adhesive to the back of the holder instead and then put it into place. Next, I ran the #8 machine screw through the hole in the foot and adjusted until z homes properly. Then I changed the Slicer Settings -> Custom G-Code to disable the autolevel function completely by replacing it with the following custom g-code:\n;G-CODE BEGIN\nG28 ; home all axes\nG1 Z5 F5000 ; lift nozzle\nM109 S220 ; set the extruder temperature and wait for filament to solidify\nG28 Z0 ; Home z again, in case there's some filament still attached to the nozzle\nM565 Z0 ; reset Z offset\n;G29 ; probe the bed - disabled by me so as not to initiate autolevel\nG1 Z-3.2 F5000 ; a negative offset of 3.2 units is applied at the beginning of each print to lower or raise the extruder tip relative to the hotbed, depending on where it would otherwise hit first.