4.3.3-RC Firmware for Original Prusa MINI/MINI+  

4.3.3-RC Firmware for Original Prusa MINI/MINI+

Hello all, we are happy to present our latest improvement to the Prusa MINI/MINI+ firmware;

Summary

• Support for custom extruders
• Nozzle pressurizing improved
• Extended print statistics (Odometer)
• BSOD caused by a broken thermistor fixed

This is the first public release candidate of the upcoming firmware 4.3.3. Based on the request from the community, the developers are introducing several new features.

Compared to the previous release 4.3.2, there are 34 commits in 8 merge requests and a significant amount of testing time.

Support for custom extruders

Based on the requests from the community this firmware release enables users to install and tweak settings for a custom extruder on the MINI and MINI+. Previously this was only possible with custom firmware.

Installing a custom extruder is a significant change to the entire printer and might require multiple adjustments afterward. Therefore we recommend using this feature only in case you have some experience in this field.

To adjust settings for your custom extruder, go to LCD Menu -> Settings -> HW settings -> then long-press the knob. Similarly to a MK3S+ a new “Experimental” submenu will appear on the screen, where you can tweak the following:

• Save and return - while exiting this dialogue any adjusted value will be automatically saved
• Z-axis length - here you can adjust the length of Z-axis based on your needs. In case you want to increase its length significantly, don't forget you might get limited by the cables.
• Default Z length - the system will fall back to its default value, which is 185 mm.
• Extruder steps per unit - different extruders might require different stepping
• Default steps per unit - the system will set the factory value, which is 325
• Extruder direction - there are two choices of spin, “Prusa” and the second is obviously “Wrong” 😉
• Default directions - set the direction back to the default (Prusa)

Once parameters are adjusted, click on “Save and return”, the printer will ask you whether you want to save the changes to the EEPROM and then restarts itself. When the printer boots up again, the changes are applied across the system. This was done to ensure that even with adjusted parameters the printer will be still able to perform First Layer Calibration, Live Adjust Z and, of course, print.

Nozzle pressurizing improved

In some scenarios, after a filament change, the printer created a blob imprinted in the object. Removing this surface irregularity was hard once the filament solidified and for this reason, the developers have improved the algorithm responsible for the filament change. It is based on the one used in the MK3S+.

Once the proper filament change is confirmed by the user by selecting “Color correct”, the printer starts to pressurize the nozzle to achieve even filament distribution. This results in a thin string of filament being pushed out of the nozzle. It is necessary for the user to remove this string with pliers or another tool before the nozzle reaches back to the printed object. It is important to note that the NOZZLE IS VERY HOT at this point, thus removing the string by fingers will inevitably result in burns.

This behavior is now used by default every time a filament change is triggered during the print by command M600. If the printer is stationary and load/unload/filament change is selected manually by the user, then the nozzle pressurizing is not activated.

Extended print statistics (Odometer)

Another frequent request by our community is implemented in this firmware release. The printer now stores information not only about the filament used and print time but also about the distance traveled at each axis (X, Y, Z), which is displayed in meters.

This feature opens the door for multiple features, some of them will be introduced in the upcoming releases. For example:

• Planned printer maintenance - once the bearings or other components reach a certain threshold, the printer will inform the user and provide instructions on how to clean, maintain or replace selected parts.
• Storing print statistics to a server - once the printer will be connected to the upcoming Prusa Connect service it will send the statistics and enable easier management of larger farms
• .Becoming a 3D printing grandmaster - the printer is capable of storing a print time of 9999 days 99 hours. The first user to reach this value without any tricks will become a grandmaster of 3D printing.

All print data is stored in the EEPROM. To optimize the number of writes to the memory, only finished or stopped prints are saved. In the case of a watchdog reset mid-print, the data is not stored.

BSOD caused by a broken thermistor fixed

The developers have identified an incorrect printer behavior in a situation when the print is run remotely using Octoprint and the thermistor either gets broken or is accidentally removed from the Buddy board.

Instead of properly displaying the red screen (THERMAL RUNAWAY/MINTEMP), the printer crashes to BSOD or the Watchdog reset screen. This is now fixed and this might also resolve other situations, where the printer is showing the Watchdog reset.

Supported printer:

Original Prusa MINI

Original Prusa MINI+

Download Link:

https://github.com/prusa3d/Prusa-Firmware-Buddy/releases/tag/v4.3.3-RC

How to flash the firmware on MINI:

Copy the firmware file (.bbf) onto the USB drive with FAT32 formatting Insert the flash drive in the MINI's USB port Turn the printer ON (or reboot it) A new screen will appear Confirm you want to flash the firmware

Please report any bug here:

github.com/prusa3d/Prusa-Firmware-Buddy/issues

As always, we wish you happy printing and look forward to your feedback!