3.12.1 Firmware for MK3, MK3S, MK3S+, MK2.5 and MK2.5S

Summary

• Thermal model - important info
• Restore correct RPM for fans
• Set the calibration state when running M310 A
• Non-responding MMU2S fixed
• Max Z-coordinate during Nozzle Change
• Beeping after Factory reset fixed
• Message selection fix
• Known issues

This is the final release of firmware 3.12.1 focused on bug fixes and small improvements.

Thermal model - important info! (MK3/MK3S/MK3S+)

The previous firmware release (3.12.0) introduced an important enhancement to the printer’s overall safety - the Thermal Model which continuously monitors the printer and raises an error if there’s something wrong. While upgrading the firmware, a calibration procedure is enforced to ensure this feature works correctly.

If you have the stock printer and the display shows “thermal anomaly detected” messages during the print, it’s a serious issue - do not take it lightly. Please, inspect the printer and check for any possible issues. Downgrading the firmware will get you rid of the messages, but the underlying HW issue will still remain.

In case you are running 3rd-party parts like the Revo hotend, the thermal model will report errors because it needs to be trained on a large set of samples. We welcome anyone who’s willing to help us with testing. Please provide log files in GitHub issue. For now, you can disable the Thermal Model if you’re running the Revo and you’re certain that your printer is working fine. Connect to your Printer via Pronterface and send G-code M310 S0 followed by M500 - then you can continue using the firmware with third-party parts.

Restore the correct RPM for fans (MK3/MK3S/MK3S+)

In case of a Thermal model error, both fans spin at full speed to cool down the nozzle as fast as possible. In firmware 3.12.0 the fans kept spinning at 100 % RPM even after the TM error was cleared. This has been fixed now and the fan speeds are regulated based on the current temperatures.

Thanks to our community members @gregsaun, @Aldebaran91, @arekm, @matthew-humphrey reporting the issue.

Set the calibration state when running M310 A (MK3/MK3S/MK3S+)

Calibrating the Thermal model using the G-code command M310 A F0 didn’t set the TM calibration state correctly. This is now fixed and calibration is stored as expected.

Kudos to our community members @arekm, @FrHePo and @gregsaun for reporting this issue.

Non responding MMU2S fixed

Firmware 3.12.0 accidentally introduced a bug, where the MMU2S unit might stop responding in case of an error. For more details, see issue #3742. This is now fixed and the unit will work as expected.

We would like to thank our community members @RPospisil, @ursius2020, @E-Extrude, @Hauzman, @Mirarkitty and @3dprintandpaint for reporting this bug and retesting the fix.

Max Z-coordinate during Nozzle Change

If the “Nozzle Change” feature is used, the printer will raise the extruder to its max Z-coordinate value making the nozzle exchange easier.

This change was done based on the request from our community member @laskr1999.

Beeping after Factory reset fixed (MK2.5/MK2.5S)

Some users have reported that MK2.5 and MK2.5S printers keep on beeping after the Factory reset is performed. This release fixes the issue.

Kudos @cjshaker for reporting this issue.

Minor message selection fix

When the user tried to re-run the wizard they got a message if they wanted to delete previous wizard data and run the wizard again. The button meanings in this screen have been accidentally swapped (“No” was actually starting the wizard). That is now fixed, re-running the Wizard now continues correctly selecting “Yes”.

Known issues

• Accidental reset of the printer during temp calibration will cause Wizard to be run on the next boot.
• Pausing MMU prints while the MMU is performing the filament change may cause FW crashes.