Sunday, December 06, 2015

3D Printer Auto Bed Leveling Geeetech Prusa i3 Pro X

I used a NPN inductive sensor model LJ12A3-4-Z/BX

It is specified to work on 6v to 36v power but mine worked on 5v off the GT2560 board so it was just perfect.

I wired it like below:

SENSOR               BOARD




Made the following changes to the Configuration.h file of the firmware, change the Z_MIN_ENDSTOP_INVERTING to true compiled and uploaded the firmware.

const bool Z_MIN_ENDSTOP_INVERTING = true;

Enabled bed auto leveling:


Set defaults on the leveling grid and sensor position:

    // set the rectangle in which to probe

Set the grid points to 3 so it will check 9 points in the bed.


Set the grid points to check:

      #define ABL_PROBE_PT_1_X 15
      #define ABL_PROBE_PT_1_Y 180
      #define ABL_PROBE_PT_2_X 15
      #define ABL_PROBE_PT_2_Y 20
      #define ABL_PROBE_PT_3_X 170
      #define ABL_PROBE_PT_3_Y 20

Compiled and uploaded the firmware.

The red light will always be turned on but will get brighter once it get nears a metal object.

The default Geeetech firmware can be downloaded from here:

You can buy the sensor here.

UPDATE 10/12/2016

I have replaced my sensor with a capacitive sensor and it works on glass or any surface:

For the one requesting the wiring here's an image of the Geeetech board. Power was taken from an unused fan port.


Unknown said...

Hi. Can you post a video how to assemble the sensor on to the printer?

Unknown said...

Can you show how you have connect the wires on the GT2560 because the end stop has a connector and now pins to soder on. So tell me.

Unknown said...

I solved it

Unknown said...


Please tell me how to connect the Wires on the GT2560!

Can you send me a Photo?.

My email Adress:

Thanks alot!.

barry said...

Would love to get a schematics of the wiring pease

Unknown said...
This comment has been removed by the author.
Unknown said...

Please share how you mounted the sensor to the extruder carraige. Thank you in advance!

Ελ said...

need help

I have put the sensor at the head
I have make the changes at the configuration.h file
I have compile and download the code at the board
but when I choose to auto home It homes the x,y and the head goes to the middle of the table it goes to zero and then stop. It can not move to check the other points.

any suggestions?

Ελ said...

To chech the other points I put at the gcode after the G28 the command G29 S1;
That start probing the other points


Shiva said...

please send me picture where i have to connect wire?
my id

PressEjectOnPlay said...

I have updated the post with image on how to wire and the new sensor I am using that works on glass or any surface. It is a capacitive sensor, its a bit fatter but it works really well on any surface.

Eduardo Fernández said...

Good morning, a question the z-axis sensor is completely replaced or placed in parallel with the proximity detector.
You can show me a physical photo of the connection you've made.
Thank you very much, thank you.

Unknown said...

Hi Have done same enhancement on my i3x.
Everything OK except the fact that Z offset tuning doesn't work.
- I have done the fine tuning of z-offset and implemented the measured figure in Marlin software
- but when I try to print, the hotend remains at the level defined by induction probe detection in G28, some 6/10 mm over the bed.
This distance bed-hotend is always the same, independant of the offset figure in Marlin software...
did anybody have the same trick ?

Thaks for this post