BL-Touch Installing Guide for LK4PRO & LK5PRO

BL-Touch Installing Guide for LK4PRO & LK5PRO

Longer LK4PRO & LK5PRO are two FDM Printers capable of producing high quality 3D prints. However, you can increase the ease and quality of printing by installing a BL-TOUCH or 3D-TOUCH compatible automatic leveling sensor.






  1. Switch-off the printer
  2. Find the position of motherboard, then screw down the mainboard cover
  3. Unplug the Z-MIN wire (2 pin) from the mainboard
  4. Connect the sensor's cables to the motherboard, as the picture showing below


  1. Screw up the mainboard cover
  2. Remove the Z endstop switch, as picture showing below


  1. Screwdown left 2 screws of PrintHead module and mount the BL-TOUCH as picture showing below (follow the same step if you have DualBlower)



  • Confirm BL-TOUCH wiring and mounting is complete
  • Power ON the printer
  • Connect PC and printer with the modified USB-cable
  • Open Pronterface software, select serial port (115200 baudrate) and connect it to the printer


Adjusting Z-Offset

  1. Clean up bed and nozzle, and ensure no materials stick on 
  2. Send M851 Z0 to reset Z offset value  
  3. Send G28 to homing XYZ axis
  4. Send G1 F60 Z0 to lower Z axis to the software origin 
  5. Send M211 S0 to inactivate software endstop function
  6. Place a sheet of paper (0.10mm approximately) on the bed and use Pronterface to lower the nozzle 0.1mm by 0.1mm until you feel a friction between the nozzle and the sheet of paper (the paper is not to be jammed but not too free either). Then remove the sheet
  7. Send M114 to get current Z height value (usually negative) and take note of it. This is the z-offset value we need
  8. Send M851 Z-x.x to set z-offset (x.x is the value of previous value; for example, if previous value is -1.2, then send M851 Z-1.2)
  9. Send M500 to save current settings
  10. Send M211 S1 to re-activate software endstop function 
  11. Send G28 to homing XYZ axis
  12. Send G1 F60 Z0 to test if Z axis could back to the actual Z origin by checking the clearance between bed and nozzle if is about 0.1 mm (thickness of a sheet of paper). If not, please repeat steps from 1 to 11.


START GCODE replacement

Inside the Slicer software (Cura, Slic3r, Simplify3D), replace the original START GCODE with the following START GCODE for BL-TOUCH.

G21 ; metric values
G90 ; absolute positioning
M82 ; set extruder to absolute mode
M107 ; start with the fan off
; confirm BL-touch safety
M280 P0 S160 ; BL-Touch Alarm release
G4 P100 ; Delay for BL-Touch homing
G28 X0 Y0 ; move X/Y to min endstops
G28 Z0 ; move Z to min endstops
; reconfirm BL-touch safety
M280 P0 S160 ; BL-Touch Alarm realease
G4 P100 ; Delay for BL-Touch
; bed leveling
G29; Auto leveling
M500 ; save data of G29 and M420
M420 S1 ; enable bed leveling
; prepare hot-end
G92 E0 ; Reset Extruder
G1 Z2.0 F3000 ; Move Z Axis up little to prevent scratching of Heat Bed
G1 X0.1 Y20 Z0.3 F5000.0 ; Move to start position

G1 X0.1 Y150.0 Z0.3 F1500.0 E15 ; Draw the first line

G1 X0.4 Y150.0 Z0.3 F5000.0 ; Move to side a little

G1 X0.4 Y20 Z0.3 F1500.0 E30 ; Draw the second line

G92 E0 ; Reset Extruder

G1 Z2.0 F3000 ; Move Z Axis up little to prevent scratching of Heat Bed

G1 X5 Y20 Z0.3 F5000.0 ; Move over to prevent blob squish
; -- end of BL-TOUCH START GCODE -- 




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