Skip to main content

Marlin Collision Sensing

Info

This feature requires the BD sensor firmware version (which can be obtained by sending the M102 S-1 command, not the hardware version on the sensor) to be V1.1b, greater than V1.2b, or purchased after March 2024. Otherwise, you need to use an external hardware tool (such as ST-Link) to flash the firmware into the BD sensor.

How It Works

  • Automatically calibrates the Z-offset during G28 execution: It can trigger after homing (when the nozzle touches the platform) — then slowly moves upward until the nozzle just leaves the platform — setting this position as the Z-axis zero point.

Benefits

  • Automatic Z-offset calibration.
  • At the same time, you can still manually adjust the Z-offset for different filaments.
  • Overcomes temperature drift.
  • Temperature drift changes the Z-offset, but it does not affect the range of the bed mesh height map with the BD sensor. This means the bed mesh remains the same even at different temperatures.
Tip

The code for this feature is in the pull request list of the official Marlin GitHub: https://github.com/MarlinFirmware/Marlin/pull/27243 Therefore, use the following Marlin code: https://github.com/markniu/MarlinPULL/tree/bugfix-2.1.x

How to Use

Enable BD_SENSOR, and add #define BD_SENSOR_CONTACT_PROBE in configuration.h It should look like this:

#define BD_SENSOR
#if ENABLED(BD_SENSOR)
  #define BD_SENSOR_PROBE_NO_STOP // Probe bed without stopping at each probe point`
  #define BD_SENSOR_CONTACT_PROBE // it uses nozzle collision sensing to probe while homing`
#endif

  • Increase the probe speed in configuration.h.

  • Sensitivity depends on speed, so you need to adjust the Z-axis speed.

  • homing_speed and second_homing_speed should be in the range of 3 to 10, here is the Z-axis probe feed rate.

  • For example:

 #define Z_PROBE_FEEDRATE_FAST  (5*60)
 #define Z_PROBE_FEEDRATE_SLOW  (5*60)
  • In Configuration_adv.h, increase the Z-axis homing lift to greater than 4 mm.
#define HOMING_BUMP_MM      { 5, 5, 5 }

Testing Homing

  • Please send the G28 Z command about 10 times, or use the M48 command, to see if it is stable.
Demo Video
Loading...