Introduction

This article is to help the LONGER LK and LK Pro series 3d printers users who want to upgrade with auto bed leveling sensor, like BL-TOUCH, etc. More information about senor please refer to the sensor datasheet.

Preparation

• LONGER FDM 3D Printer LK or LK Pro series
• BL-TOUCH or other similarsensor
• Sensor attached wires(5pin)
• Sensorattached screws and nuts(2 pairs)
• Sensor mount(printed .stlmodel)
• USB cable
• Pronterface or other serial port communication software
• 50k ohm or 100k ohm resistor(LKx series users only)
•                                                                                                                                             

          Wiring

1. Switch-off the printerpower
2. Find the position of motherboard, then screw down the mother board cover. 
3. Unplugthe Z-MIN wire(2 pin) in board
4. 4.Hook up the sensor and the motherboard. LKx series users need parallel a 50 or 100 k ohm resistor between 5V pin and PWM pin as the picture showing below
5. Screw up the mother boardcover

                                                                                                                                                                                                                                     LKx series board wiring need extra resistor

                                                                                                                                                                                                                                                                                             LKx Pro series board wiring

Mounting

1. Removethe Z axis end stop switch as picture showing below

                                                                                                                                                                                                                                                                   Remove the z min end stop switch

2. Screwdown left 2 screws of head module

3. Mount BL-TOUCH as picture showing below 

                                                                                                                                                                                                                                                                                                                   Mount sensor

 Power on

1. Confirm BL-TOUCH wiring and mounting iscomplete
2. Switch on the printer power
3. ConnectPC and printer with USB-cable
4. Flash BL-TOUCH dedicated firmware .Check the firmware update manual if you need.
5. Open pronterface software, select serial port(115200 baudrate). and connect to 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 (or other block of 0.10mm approximately) on the bed and use the pronterface to lower the nozzle 1mm by 1mm then 0.1mm by 0.1mm until you feel a friction on 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). the value is the z-offset we need.
8. Send M851 Z x.x to set z-offset(x.x is the value of previous value)
9. Send M500 to save current settings.
10. 10.Send M211 S1 to re-activate software endstop function 
11. Send G28 Z0 to homing Z axis
12. 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 step 1 to 11.

Adjusting auto leveling

Replace GCODE

1. Replacewith new START GCODE(in appendix section) in your slicer software(Cura, Slic3r, Simplify3D, )
2. Have fun! :)

Appendix

-- BL-TOUCH START GCODE --
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
M420 Z5 ; set LEVELING_FADE_HEIGHT
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 -- 

Files Download:

PC Software: >>pronterface-windows<<

Mouted Bracket: >>Bracket<<

The firmwares has been codeed by LONGER, you would download the firmware and upgrade directly:

>>For LK1(U20)<<

>>For LK1 Plus(U20 Plus)<<

>>For LK4(U30)<<

>>For LK4 PRO(U30 Pro)<<

>>For LK5 PRO<<

If you have install dual blower kit, use dual blower kit Mouted Bracket: >>Bracket<<, and download below firmware and upgrade directly:

>>For LK1(U20)<<

>>For LK1 Plus(U20 Plus)<<

>>For LK4(U30)<<

>>For LK4 PRO(U30 Pro)<<

>>For LK5 PRO<<

If there's any question or need assistance from us on the upgrade, please feel free to contact us at support@longer3d.com, LONGER support team will follow up and reply you ASAP.

Thanks