Summary

Description

The 3dprintingstore.co.za Prusa i3 uses a micro switch on a servo with the auto bed-leveling upgrade kit. I really like the auto bed leveling feature but never really trusted the repeatability of the switch on the servo.

This is an upgrade to replace the servo mounted micro switch with a bltouch sensor. Wiring of the Bltouch is great, you directly replace the servo and z end stop connectors with the matching cables on the Bltouch. Reference the attached image.

I included two files to support both E3Dv5 and E3Dv6 hotends. The height of these hot ends differ by 7mm and the Bltouch need to be mounted accordingly, ensure you use the correct model for your hotend, the printer ship with an E3Dv5 hotend.

Note: I have not tested the E3Dv5 version. Let me know if I need to make some corrections.

Firmware Settings

In addition you will need to make the necessary changes in the firmware configuration.h. I used the marlin firmware supplied by 3dprintingstore.co.za for auto bed leveling and made the necessary adjustments.

1. Ensure you enable servo 0 and set the servo angles
   #define Z_ENDSTOP_SERVO_NR 0 // Defaults to SERVO 0 connector.
   #define Z_SERVO_ANGLESS {{0,0}, {0,0}, {10,90}} // Servo Deploy/Stow angles

2. Enable the Bltouch sensor in firmware
   #define BLTOUCH

3. Correct the probe offset
   #define X_PROBE_OFFSET_FROM_EXTRUDER 25
   #define Y_PROBE_OFFSET_FROM_EXTRUDER -30
   #define Z_PROBE_OFFSET_FROM_EXTRUDER -0

4. The Bltouch have much lower tolerances than the servo/switch so reduce the max offset to acomodate.
   #define Z_PROBE_OFFSET_RANGE_MIN -10
   #define Z_PROBE_OFFSET_RANGE_MAX -1

5. Enable bilinear bed auto bed leveling and safe homing
   //#define AUTO_BED_LEVELING_3POINT
   //#define AUTO_BED_LEVELING_LINEAR
   #define AUTO_BED_LEVELING_BILINEAR
   //#define AUTO_BED_LEVELING_UBL
   //#define MESH_BED_LEVELING
   #define Z_SAFE_HOMING

6. Define the probe boundaries
   #define LEFT_PROBE_BED_POSITION 25
   #define RIGHT_PROBE_BED_POSITION 175
   #define FRONT_PROBE_BED_POSITION 30
   #define BACK_PROBE_BED_POSITION 170

GCODE commands

Once you load the firmware you will be able to test the Bltouch using the following Gcode commands.

M280 P0 S10 ; lowers the pin
M280 P0 S90 ; retracts the pin
M280 P0 S120 ; Runs a self test - until you lower/retract or release alarm
M280 P0 S160 ; Release alarm

If you have a 3dprintingstore.co.za Prusa i3 you might also like my other upgrades for this printer.

• Minimalist Direct Drive Extruder - https://www.thingiverse.com/thing:3224826
• Carriage Cable Management Arm - https://www.thingiverse.com/thing:3224881
• Prusa i3 blower fan upgrade - https://www.thingiverse.com/thing:3225085