Ender-3-3DPrinter-Load-Cell-Bed-Leveling-Sensor

This is a Load Cell based bed leveling sensor that should mount onto any vertical MGN12H gantry It uses

• ADS1235 ADC due to its 24-bit ADC, 7.2k sampling rate, 128x PGA gain.
• RP2040 MCU to do all the processing
• 500g TAL 221 Loadcell due to its compact nature. My gantry weighs around 250g. So make sure to select appropriate loadcell based on your gantry's weight so as to not saturate the loadcell.

My 3d printer is an Ender-3 with 3dFused's linear rail kit and it perfectly works with that.

PCB

You can order this PCB on OSHPark. Alternatively, the KiCad Schematic is available on github and the Digikey parts list here

Source code and mounting bracket

Code

The Arduino IDE code is available here.

• Install Arduino IDE
• Install the following Arduino Libraries
  • PioSPI
  • Adafruit NeoPixel
  • RunningAverage
• Try compiling the binary

Alternatively, you can flash the precompiled binary

Normal Operation

• If everything is wired correctly, as soon as you power on, the LED should be RED for a few seconds and then turn off. If it flashes red, then there is an error. Try connecting the USB port and check the debug message printed to serial.

• When the sensor is probing, the LED should turn blue to indicate that it is probing and turn green for a short while when triggered.

Tuning

DELTA_FOR_TRIGGER is the main tuning variable that controls the sensitivity of the probe.

• Typically, set DELTA_FOR_TRIGGER to a low value like 1-2 and set is_probing = true
• Reset your printer and as soon as it starts, the LED should be BLUE. Note that it might get triggers very easily and turn green since the threshold above is low.
• Keep the filament wire into the extruder tight and try to extrude filament or move the printer head and keep bumping up DELTA_FOR_TRIGGER till such motions don't trigger.
• Now the probe will only trigger for probing motions

Z-Probe Repeatability Test