Mod 10 for the BIQU B1: replace weak and loud fans with 5015

This is a mod I intended to do when I first heared a grinding noise from the fans used in my BIQU B1. Today the right fan stopped working and I don’t have enough cooling anymore.

BIQU will send me replacement fans but I can’t wait…

I had two spare 5015 fans and found a nice design on thingiverse:

Now I can see the nozzle and this first layer is way off…. 🙂

Mod 9 for the BIQU B1: replace flimsy spring steel sheet with sturdier PEI coated

The standard spring steel sheet is quite flimsy and hence sometimes I struggle putting it on the heatbed in the right position. The coating doesn’t stick enough for PLA without glue stick. I replaced it with a PEI coated sturdier one.

Mod 8 for the BIQU B1: replace extruder with BMG clone (replaces Mod 3 and 4)

As I had some extrusion problems with Innopet, I changed the extruder to a BMG clone.

Mount for the smart filament sensor:

I wouldn’t recommend the BMG clone you can see on the picture as it doesn’t let filament through, when the stepper motor is blocked, evan if you pull the lever.

Mod 7 for the BIQU B1: relay module to shutdown printer with gcode (M81)

Designed a mounting case for the MKS PWC 3.0

Mounted it inside the controller box:

Wired everything and added the power button:

Modified Marlin (configure PS_ON_PIN..), compiled and flashed it.

Added M81 to G-CODE at the end for PrusaSlicer.

Mod 6 for the BIQU B1: Marlin bugfix release

The smart filament runout sensor did trigger way to often. So I tried the bugfix branch of Marlin 2.0.x. Digging in the config files I found a feature to list the gcode-files when you insert the SD card. Prusa has this feature in their printers in their firmware since long ago and I really missed it on this printer.

You can find my configuration on

It is printing now for more than 5 hours without any problems.

Mod 4 for the BIQU B1: smart filament sensor

The standard filament sensor can not detect, if the hotend is clogged or the filament is broken between the sensor and the extruder.
BTT sells a nice smart filament sensor which detects filament movement and can detect these failures.

I don’t like the way BIQU adds the sensor:

  • it is in between the extruder and the hotend and adds length to the bowden tube
  • it is monitored by the TFT module and is only working, if you print with this module

More to my taste:

  • mounted BTT smart filament sensor with the mount from
  • rewired the sensor from the touch screen to the mks controller board
  • modified firmware to use the sensor
  • now it should work with octoprint

On the right side you can see Mod 4 (smart filament sensor).

Here you can find source code for the firmware changes I made to Marlin:

Mod 1 for the BIQU B1: ABL

I want to use different print surfaces with different thicknesses. With ABL I don’t have to level with every change of the suruface.

  • I added a BL Touch clone with the no spring mount of
  • modified firmware to use only the probe for z-homing
  • removed the z-endstop screw
  • detached the z-endstop
  • lowered the bed with the leveling screws for about 2 mm
  • modified prusaslicer profile to ABL (G29) when the bed is heated

Here you find source code for the firmware changes I made to Marlin: