G30the bed will move up toward the nozzle until the Z-probe is triggered. When the Z-probe is triggered, the Z-value of the printer is set to the Z-offset of the Z-probe. You can set the Z-offset of the Z-probe with the
G31command and its parameters.
G29. This is extremely important, otherwise you will crash the nozzle into the print bed as the Z-probe will never be triggered.
G1 X187 Y154
nnnis your temperature in °C. You can always look up the recommended bed temperatures for specific materials online. For PLA, a bed temperature of 50°C will work well. For ABS-R, a bed temperature of 60°C is recommended.
G31 P999 X-40 Y28.5 Z0. This will make it easier to gauge the distance between the Z-probe and the nozzle in the following steps.
G29 S2. This clears any active bed leveling compensation. This is very important as it will conflict with your updated Z-probe offset and induce a 0.1 - 0.3mm error depending on the magnitude of your bed leveling compensation at that point. This will be explained in the section below.
G1 Z20. When you send the command
G30the bed will move slowly and precisely to the Z-probe, if you send
G30while the bed is at
Z100or greater you will have to wait for a long time for the Z-probe to trigger.
G30. This will move the bed toward the z-probe until the limit switch triggers. If you don't deploy your limit switch probe, it will never trigger because the bed hits the nozzle. The bed hitting the nozzle is called a crash, if this happens it might misalign your bed and you will have to follow a separate guide to fix the problem.
M564 S0to disable the axis limits. To learn more about this command visit the RepRap G-code wiki.
G31 P999 X-40 Y28.5 Znnnwhere
nnnis your Z-probe offset.
M564 S1. This will prevent you from crossing the axes limits again.
G31command there, just like you did in the . Follow the steps below to make this change.
G31command with your offset to be added to this start-up sequence. This will prevent you from having to follow the steps above continuously.
G31commands. You will note that there are two of them.
;in front. This denotes a comment, and thus that command will not take effect when the file is run. One of the
G31commands configures the offsets for the IR Z-probe and the other for the limit switch Z-probe. The comments should indicate which one is what. Fix the Z-probe Z-offset of the limit switch. Your
G31command might look like the command below (
nnnrepresents your Z-probe Z-offset, ):
G31 P999 X-43 Y25 Znnn ; Set Z probe (limit switch) trigger value, offset
G29 S2, this will disable any current bed leveling compensation.
G29, this will engage the bed leveling process. The extruder carriage will move over the entire build plate and probe bed. This can take a few minutes, so continue on to the next step where I explain what bed leveling does.
M557command. Check it out on the RepRap wiki for more information. It shouldn't need to change, but you can reduce it if you want to sacrifice accuracy for a shorter wait time. The bed leveling procedure will generate a heightmap file called heightmap.csv on the SD card. This file stores the data for the bed leveling compensation. Whenever the bed leveling procedure finishes, you will see this heightmap file visualized on the screen. If you ever want to see the heightmap again in the future you can select Show Mesh Grid Heightmap in the Auto Bed Compensation tab of the Machine Control tab on the Duet Web Console (shown in the image below).
G1 Z0.2for the first layer, it will be compensated for by the local and interpolated value obtained from the heightmap. So the board might actually go to
Z-0.3depending on the local heightmap value.
G29 S2, if you want to re-enable bed leveling without running the bed leveling procedure, send the command
G29again will overwrite the previous heightmap.
G29 S2in order to avoid the propagation of heightmap values. Things that can be affected:
G29multiple times in succession, but these are known to have bus. We recommend running
G29 S2before doing any of the actions in the list above. If you forget to disable mesh bed leveling, you will not have catastrophic results, just an error of around 0.5mm or so. Just barely enough to mess up your print.