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:

Having fun with the BIQU B1

I sold my Prusa i3 mk3s (shame on me)

Seeing all the innovation coming from China I asked myself: Is the price of the Prusa i3 mk3s still ok? I know the quality of the i3 mk3s and really appreciate the experience you have using prusaslicer with it. But then: the hardware is really outdated.

What should IMHO be improved in the next iteration of the mk3s:
– 32 Bit controller
– nice casing for the controller and the psu
– maybe a colorful touch screen
– easier setup of the kit

The Prusa MINI is a step in this direction. Take the controller from the Prusa MINI, add a nice casing and preassemble more parts. voilà the Prusa i3 mk4

Prices are still high for the MK3S and I sold mine. For half the money I got, I bought a BIQU B1 and like it very much:
– modern 32 bit board
– runs with Marlin (I have compiled my firmware 🙂 )
– is easy to setup
– makes wonderful prints

– responsive support
– widely used components (SKR boards, TFT) from BT

There is room for improvement here too:
– remove the leveling knobs and use a BL Touch (or clone)
– reduce the fan noise (it is not too bad, but can be improved)
– publish the schema files for the hotend/USB-C pcb so we can easily add new hotends
– give us the choice for a direct extruder
– make it easy to order spare parts from your shop on aliexpress

If I were the designer of the new Prusa CoreXY printer

I would consider

  • to check filament movement and detect jams
  • to use TMC 2209 with sensorless homing
  • to use dual z-axis with G34
  • to use something like a mosquito or a dragon hotend (V6 are a pain if you wan’t to change nozzles and the cooling is inferior to other designs)
  • to use a change tool mount like
  • not putting the belts unprotected on the top (not like the design of the Tronxy X5SA Pro)
  • make it rock solid like the Prusa i3 mk3s I have
  • use all the cool features of the i3 mk3s (like magnetic powder coated PEI sheet or the direct drive extruder)
  • having the possibility to easily attach walls to make a heated chamber
  • offering differrent sizes: normal like the i3 mk3s, large (330x330x400), extra large (400x400x500)

and to use me and myself as betatesters… 🙂

Update 5 on Jun 22, 2020: Build log Tronxy X5SA Pro

Powder coated spring steel sheet arrived:

It is so nice to use. Big prints can be removed just by bending the plate. Well done!

I don’t understand, that someone would build a printer without a removable flexible build plate (thanks Josef :)) today. There is at least one much hyped printer on kickstarter that doesn’t have one…. 🙂 (And influencers may be paid for hyping it?)

Yes, I know I have to improve cable management… 🙂

Update 4 on Jun 18, 2020: Build log Tronxy X5SA Pro

Mosquito clone integrated into my build:

Added 3D Touch sensor. To use it for Z-homing, I had to use the predefined Z-min endstop pins and couldn’t use the pins provided by the SKR 1.4 board for BL Touch. I think, there is a bug in the version of Marlin I use.

Added extra stepper driver for each Z-motor. For the Z-axis alignment I use the 3DTouch sensor with Marlin G34.

Added BMG extruder clone.

And blown a 10A fuse…. 🙂