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6.0.0-RC1 Firmware for Original Prusa MK4 & MK3.9

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Jakub Dolezal

(@jakub-dolezal)

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6.0.0-RC1 Firmware for Original Prusa MK4 & MK3.9

Summary

MMU3 support for the MK4/MK3.9
Using the MMU3
Touch support MK4/MK3.9
Stuck filament detection
Cold Pull
Stealth mode
Time Zone settings updated
Improvements by Prusa community

This firmware introduces support for the Original Prusa MK4/MK3.9 with MMU3, which has been thoroughly tested and confirmed as stable. We have also included several brand-new features, which can be used regardless of the MMU3 unit and are still under development. As these features are undergoing further refinement, this firmware is labeled as a release candidate.

MMU3 support for the MK4/MK3.9

Currently, the MMU3 unit can be paired with MK3S+ and MK3.5, while this release adds support for MK4/MK3.9. It is important to note that each printer requires its own hardware upgrades as well as firmware versions to function properly with the MMU3.

Since the MK4 and MK3.9 utilize Nextruder, certain parts of the firmware had to be specifically tailored for its sensors (loadcell, filament sensor, etc.). This also affected the behavior such as calibration, automated checks, and troubleshooting compared to the MK3.5 or MK3S+ MMU3 setup.

Throughout the rest of these release notes, the MK4 and MK3.9 will be treated as equivalent printers, and only MK4 will be mentioned.

Single material MK4 calibration

As usual, before you install the MMU3 on your printer, make sure the MK4 was successfully calibrated and at least one single material print was done. The Multi-Material Upgrade adds more complexity to the entire setup and in case of issues, this move significantly improves the troubleshooting experience.

Upgrade your MK4 Nextruder

To use your MK4 with the MMU3, you need to upgrade your Nextruder with new printed parts, which will require a partial disassembly of the print head. All the parts are included in the MK4 MMU3 packages and available on the Prusa e-shop.

Tip: If you are already running an MMU3 with MK3S+ and would like to upgrade to either MK3.5, MK3.9, or MK4, the parts will be available shortly on the e-shop as well.

Connect your MK4 with MMU3

Before you fire up the printer, you need to use the MMU3 xBuddy cable, which is either part of the MMU3 MK4 package or can be purchased separately on the Prusa e-shop.

Enable MMU3 & MK4 setup

The multi-material setup is by default disabled and has to be enabled in two places:

First, head to Menu -> Settings -> Hardware -> Extruder and set the value to “MMU”. This informs the printer that the Extruder was rebuilt with the MMU parts and the position of the filament sensor was changed. You will be asked to calibrate the filament sensor again.
Second, go back to Settings -> and set the row “MMU unit” to “Enabled” (switch icon)

Tip: If you want to run single material prints without the MMU unit, the autoload trigger won't work as the position of the filament sensor is changed. For this reason, the feature is hidden from the menu, however, it is still present in the firmware and you can trigger the autoload by pressing on the screws with springs on the Nextruder. While using the full MMU setup this is not needed at all and the filament will be loaded all the way to the nozzle.

Shortly after enabling the MMU setup, the unit performs a self-test and rehomes both selector and idler. On the main screen, menu Filament will change its icon from single to multiple spools. Please note, that it takes approximately 10 seconds for the MMU3 unit to fully start up, during this period the Filament menu is disabled.

Update your MMU3

You need to update your firmware inside the MMU3 unit. Use the MicroUSB cable included in the MMU3 package. Download the firmware 3.0.3 linked under these release notes and flash it using PrusaSlicer like any other firmware. Note that the unit must be powered ON.

Please note, that unit's firmware 3.0.3 must be paired with the printer's firmware 6.0.0-RC1. No other version combination for MK4 is possible.

Note: The MMU3 firmware 3.0.3 can't be used with MK3.5 and MK3S+.

Calibrate your FINDA and Nextruder

Similar to the MK3S+ you need to manually adjust the position of the FINDA sensor in the MMU3 unit. Second, you need to recalibrate the filament sensor to the new parts, this is automated and you will be required to only insert a piece of the filament, the printer will load it inside the Nextruder and perform the calibration automatically.

Update your PrusaSlicer profiles

Make sure you are running the PrusaSlicer 2.7.3 (or later) and check for the profile update. Once you install the latest package, check the “Configuration Assistant” for new MK4 MMU3 profiles.

Tip: The G-codes from MK3S+ and MK3.5 MMU3 can't be run on the MK4 MMU3 setup due to multiple changes to the G-code execution (ramming sequences, wiping, …). For now, it is recommended to reslice the file.

Using the MMU3

General information

MMU3 for the MK4 brings some improvements and new features (e.g. inherited tool mapping from the XL). However, we wanted to ensure that the current MK3S+ users, who upgraded recently to MK4 will be able to use the MMU3 as they are used to.

To learn more about the features (Preload to MMU, SpoolJoin, Tools mapping screen, etc.) we recommend reading the 3D printing Handbook, which is part of the MMU3 package.

Single-material prints

Starting single-material prints is easier than ever before - just select the right printer tool and assign it to your G-code. The printer will start the print, load the selected filament, cool down a bit, perform the mesh bed leveling (MBL), and then draw the purge line.

Please note, that the tools mapping screen is displayed only when the print is started with no filament in the nozzle. Otherwise, the print is started directly without showing the tool mapping screen.

New features in development

Below are listed features that are close to being considered stable, however, some final polishing is still required. Therefore, you have to enable them manually from the menu for now.

Touch support (MK4)

The touchscreen has been part of MK4 from the very beginning of the production (which is also true for MK3.5 and XL). However, during the development phase, prior to the official launch, we encountered numerous challengers, including a hardware issue caused by one of the chips on the xBuddy board. Resolving these issues required extensive collaboration with our suppliers, multiple rounds of testing, and numerous adjustments to the firmware. This is why the touch feature is being announced today.

As mentioned earlier, you must manually enable the touch feature from the menu. Navigate to Settings -> User interface -> Touch.

With the touch enabled you'll be able to control the majority of items on the screen. You can swipe your finger up and down to scroll through the menu. Swiping left or right (depending on your preference) takes you one step back in the menu hierarchy.

There are some exceptions where the knob must be used, such as when setting the target temperature manually or while moving with any of the axes.

Tip: Touch feature is supported and will soon be enabled also for the XL and MK3.5. Stay tuned!

Stuck filament detection

Starting from this release, the loadcell sensor in the Nextruder will not only be used for the mesh bed leveling, but also for detecting whether the filament is stuck and not moving (e.g. when the nozzle is clogged).

When certain conditions are met, the print will be paused, filament unloaded and the system will notify you that the filament was most likely stuck. Once you check the filament, reload it back to the Nextruder, and then you can resume the print job.

It is important to note that detecting stuck filament is possible only inside the Nextruder, as pressure builds up from the nozzle to the upper part of the Nextruder. However, if your filament is tangled on the spool, there will be no internal pressure, just outside tension, which the loadcell won't be able to recognize.

Cold Pull

The Cold Pull method is a popular method used for unclogging or cleaning your extruder. Starting from this release we are implementing a new feature that will guide you through the entire process using a step-by-step Wizard and provide assistance.

Support for other Prusa printers is planned in a future release as soon as their implementation of the cold pull method is ready.

Stealth mode

Similar to the MK3 family, we are introducing Stealth mode, which will make your printer even quieter. This can be useful for example for overnight prints. You can switch between Normal and Stealth mode even during the print. Keep in mind that the mode will be activated once several G-code commands in the buffer (printer memory) are processed.

Once the Stealth mode is enabled, the firmware sets a limit to acceleration, feedrate, and jerk. Setting a cap on these parameters will lower the noise. While this reduces noise, it also affects the overall printing time.

In addition to Stealth mode, we are also adding support for the M73 G-code. You can find more information in this article.

Time Zone settings updated

This release increases the timezone hour offset range up to +14 hours and also introduces a timezone minutes option to select a timezone offset in minutes (0 min, 30 min, and 45 min).

This addresses issues #3550, #1779 and #3141.