I built an i3 variant running Marlin 1.1 RC8 firmware which I recently upgraded from RC6. I installed an inductive sensor LJ18A3-8-Z/BX to replace my mechanical Z endstop switch. The sensor works, it detects my aluminum build plate. When my print starts the nozzle is too far from the build plate currently by several mm. I have been pausing the print job and baby-stepping the nozzle down (using Octoprint) close enough to start the first layer. What settings do I need to change to fix the nozzle height permanently?

Right now it seems there isn't any benefit from the inductive sensor. At least with mechanical switches it was just a couple of screws needing adjustment.

Edited 1 time(s). Last edit at 01/04/2017 12:14AM by ashdavely.

You probably need to adjust the height of your inductive sensor from the build plate until it triggers exactly when your nozzle just touches the bed.

Paper test= z-height adjustment guide.

After AutoCalibration, I manually jog the nozzle down for the paper test. Then send G92 z0 and in case of Marlin M500 afterwards to store the new value in EEprom.
But your software might not allow to lower the nozzle below zero. You have to change that first or raise the sensor a bit to much, so the nozzle would crash into the bed.
That means you'd have to do the paper test at every new start.

How do you configure marlin to drop below your Z endstop? I've played with this but ended up crashing into the build plate.

Also, is Z home the same as Z0?

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ashdavely
How do you configure marlin to drop below your Z endstop? I've played with this but ended up crashing into the build plate.

Also, is Z home the same as Z0?

Send a G92 Z10 ; makes printer think its at z10 instead of Z0,
jog Zdown for paper test
Then send G92 Z0 ; resets Z0 to current position

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obewan

Quote
ashdavely
How do you configure marlin to drop below your Z endstop? I've played with this but ended up crashing into the build plate.

Also, is Z home the same as Z0?

Send a G92 Z10 ; makes printer think its at z10 instead of Z0,
jog Zdown for paper test
Then send G92 Z0 ; resets Z0 to current position

Will the firmware keep the new Z0 setting?

Quote
ashdavely

Quote
obewan

Quote
ashdavely
How do you configure marlin to drop below your Z endstop? I've played with this but ended up crashing into the build plate.

Also, is Z home the same as Z0?

Send a G92 Z10 ; makes printer think its at z10 instead of Z0,
jog Zdown for paper test
Then send G92 Z0 ; resets Z0 to current position

Will the firmware keep the new Z0 setting?

For that i think the only way would be to adjust the offset in config.h or eeprom
#define Z_PROBE_OFFSET_FROM_EXTRUDER 0 // Z offset: -below +above [the nozzle]