Summary
- MMU3 support for the MK3.5
- Using the MMU3
- Bug fixes
This is a stable release of the firmware MK3.5 recommended to all users. Starting firmware 5.2.1, we are rolling out official support for the MMU3 for this printer model. You need to update your MMU3 unit and calibrate the entire setup, so please read the instructions below carefully.
MMU3 support for the MK3.5
The latest generation of our Multi-Material Upgrade (MMU3) is now officially compatible with the Original Prusa MK3.5. This is the first release of the MMU3 working together with the 32-bit Buddy hardware. Some features are similar to the 8-bit MK3S+, some were improved fully utilizing the larger LCD of the MK3.5. Here is a quick overview of the hardware and software prerequisites with the following calibration setup:
Single material MK3.5 calibration
As usual, before you install the MMU3 on your printer, make sure the MK3.5 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 MK3.5
To use your MK3.5 with the MMU3, you need to upgrade the upper part of the extruder with new printed parts, which we familiarly call “the chimney”. All the parts are included in the MMU3 package and will soon be available on the Prusa e-shop.
Tip: MK3S+ MMU3 owners, who are upgrading to the MK3.5 can keep their extruder intact as both MK3S+ and MK3.5 are using the exact same extruder parts.
Connect your MK3.5 with MMU3
Before you fire up the printer, you need to use the MMU3 xBuddy cable, which is either part of the MMU3 MK3.5 package or can be purchased separately on the Prusa e-shop.
Tip: MK3S+ MMU3 owners, who are upgrading to the MK3.5 need to purchase just this cable, the rest of the setup remains the same as on the MK3S+. For more information visit our MMU3 compatibility article.
Enable MMU3 & MK3.5 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.
- 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 upper part of the idler door lightly. 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 3.0.2 linked under these release notes and flash it using PrusaSlicer like any other firmware.
Please note, that unit's firmware 3.0.2 must be paired with the printer's firmware 5.2.1. No other version combination is possible at the moment.
Calibrate your FINDA and “Chimney”
Similar to the MK3S+ you need to manually adjust the position of the FINDA sensor in the MMU3 unit and the Filament sensor in the “Chimney”. Please follow the official assembly instructions.
Update your PrusaSlicer profiles
We have prepared several multi-material test prints, which are available here (link). However, if you want to print your own, make sure you are running the PrusaSlicer 2.7.1 and check for the profile update. Once you install the latest package, check the “Configuration Assistant” for new MK3.5 MMU3 profiles.
Using the MMU3
General information
MMU3 for the MK3.5 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 MK3.5 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 easy as never 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.
Bug fixes
MK3.5: Sensor info - board temperature missing
This issue was reported on GitHub as #3745 and later a pull request was suggested by Bjoern #PR3749. We would like to thank the community again for engaging in the development!