RoBo3D Autolevel via Mike Kelly

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I decided to create my own version of RoBo's Auto Bed Levelness Compensation (ABLC) based on their design. I'm excited to share this with the community. Auto Bed Leveling is when the bed levelness is adjusted through mechanical action to achieve a bed that is perfectly leveled against the nozzles' movement. This is not the same as ABLC, which is a more advanced process. What is Auto Bed Levelness Compensation (ABLC)? ABLC is the process of probing the bed with a measurement device to determine the level error of the bed and compensate for this by moving the Z axis up and down. There's no mechanical variation but rather software compensation. Why is it referred to as Auto Bed Leveling? It's probably for simplicity's sake, hence why I titled this Autolevel. It's generally acceptable to trim words if your point is still made. How it works: The Robo3d has a safety measure put in place where when the nozzle touches the bed, the nuts will unseat from their housing so as to not put force on the bed and get "thrown" out. This is what people refer to when they "throw their nuts". Using this principle of the nut unseating, they used a coupling nut in its place and attached a switch to it. The switch connects to the coupling with a plastic mount. The switches then activate against the x motor carriage and the x idler respectively. With this switch in place, as soon as the nozzle touches the bed and the couplings begin to unseat, the switch will deactivate sending a signal to the ramps board that an endstop has been hit. It's used for both the Z0 sensor and the probe sensor. How mine differs: With my design, the switches are run in series to avoid a failure situation. If the switches were improperly seated or there was a failure in the wire, the RoBo3d would just raise up during its normal z operation and not throw the nuts. Build it Parts List: Printed Parts: * RoBo 3D auto level switch mount Assembly: Begin by securing the switch to the mounting plastic. It's probably easiest to thread on the coupling first before securing the switch. The bracket should expand enough to go around the threaded rods. With the mounting bracket in place, secure the M3 nut and screw and begin to tighten it down, but loose enough the plastic can still slide on the coupling. Adjust the mount distance from the idler until the switch is barely activated. The switch should activate easily when the idler presses down on it, but deactivate quickly once the coupling begins to unseat. This may take some fine tuning, but once you secure it, it should stay true. Wiring: With the switch in position, it's time to do the wiring. Current Autolevel owners: If you have RoBo3D's Autolevel switches, you can turn your parallel switches into series by unsoldering from the NC leg and soldering to the NO leg. Then, trim one of the legs short (say on red) and then another one long enough to solder onto, then modify your wiring to represent below. New to Autolevel owners: Follow the wiring diagram to wire your switches in position. You will most likely need to trim and solder to get the lengths needed. Color/polarity is not critical. Firmware: With the switches wired in position, it's time to change the firmware. This is the same Auto_Level firmware used by team RoBo, but modified with one key difference: const bool Z_MIN_ENDSTOP_INVERTING = true; is modified to: const bool Z_MIN_ENDSTOP_INVERTING = false; Which is traditional. Download the firmware below. Use either MatterControl or Arduino software to flash the firmware. It should also be noted that this firmware will work on any RoBo3d, not just the one with the Auto Bed Leveling feature. Calibration: With the firmware installed, it's time to configure the G-code to run the auto-level script and calibrate the Z height. Insert this code in the starting procedures for your slicer after the G28 codes: [code]G1 Z0.5; Adjust Z offset G92 Z0; Define new Z home G29; Autocalibrate bed[/code] That should be everything there is to it. I find it helps to monitor the output from the G29 sequence in the terminal. That way, if you see an unusual number, you'll be able to address it quicker. Ace Hardware sells M8-1.25mm couplings for anyone that has them locally.