Firmware Update: Original Prusa i3 MK3(S) / MK2.5(S) 3.7.0

Prusa Research has released new firmware for the Original Prusa i3 MK3, MK3S, MK2.5 and MK2.5S with 3.7.0 as the version number. If you also own a Multi Material Upgrade 2S, or an MMU2S, new firmware will also be included with 1.0.5 as the version number. The Prusa i3 is one of the most copied designs for 3d printers and was designed by Jozef Průša as part of the RepRap project. The list of changes for this release is as follows:

3.7.0 Firmware for MK3, MK3S, MK2.5 and MK2.5S

Detailed description of changes (compared to 3.7.0-RC1):

• 7×7 mesh bed leveling – There was a possibility of X-axis crash on the first mesh bed leveling point (issue #1674). This has been fixed. Improved mesh bed leveling (3.7.0-RC1) uses shorter Z movements to reduce overall calibration time. This in some cases leads to “Enforced Z-leveling” occurrence (issue #1651) triggered by higher variability in measured Z-values, which was probably caused by mechanical resonance. In current FW version, if Z-values ​​variability is too high for certain measured point, there is a short delay and then current point measurement is repeated with longer Z-movements (the same measurement algorithm which was used on FW 3.6.0 and all older versions).
• Duplicate T-code fix – Fixes issue #1660

3.7.0-RC1 Firmware for MK3, MK3S, MK2.5 and MK2.5S

Summary:

• 7×7 mesh bed leveling
• MMU2S fast mode (MK3S + MMU2 only)
• Improved T-code load (printers with MMU2)
• Change filament fix (printers with MMU2)
• Eject filament contains ramming (MMU2 printers)
• The informative message during switching between normal and stealth modes
• Improved behavior when removing SD card
• Autoload disabled in extruder info (MK3) and sensor info (MK3S) menu

Detailed description of changes:

• 7×7 mesh bed leveling: It is now possible to increase mesh bed leveling XY resolution by activating measuring 49 points in 7×7 mesh. This can be done in the menu “Settings -> Mesh bed leveling”. There is also a possibility to change the number of measurements for each point from 1 (fast, but less accurate) to 5 (most accurate) and also turn on/off magnet compensation. PINDA probe Z-coordinate measurement can be influenced by heatbed magnet proximity (by approximately 80 um) and thus distort mesh bed leveling calibration. If magnet compensation is off, all 49 points are measured and used for mesh bed leveling correction. If magnet compensation is on, for chosen points (which may be affected by magnets) are counted from surrounding points. Also, the mesh bed leveling Z-measurement algorithm was slightly modified to make the whole process faster. No G-code modification is needed. Standard G80 G-code will behave according to settings which were set in “Settings -> Mesh bed leveling” menu. It is also possible to use G80 Nx Ry G-code, where x is a number of mesh bed leveling points in one axis (3 or 7 are valid values) and y is number of Z-measurements for each point (which are then averaged ). Settings done directly in G-code has higher priority then settings which are set in the menu. I would like to thank all who were working on this feature and helped to implement it to our Prusa FW, especially @stahlfabrik, @mionut and @3d-gussner.
• MMU2S fast mode: On MK3S printers with MMU2 connected it is possible to switch MMU between fast and stealth mode. Fast mode can save about 5 seconds per filament change, which can speed up especially long prints with frequent filament changes. MMU fast mode should be considered experimental feature for now. For highest reliability we currently recommend MMU stealth mode. Switching between MMU modes can be done in the menu “Settings -> MMU mode”. With MK2.5S MMU always runs in stealth mode.
• Improved T code load: Load sequence was slightly modified to reduce missing layer error count.
• Change filament fix: When changing filament (M600 G-code, menu “Tune-> Change filament” or filament runout) on printers with MMU2 connected, there is a possibility to re-do filament unload and load by choosing “Filament not loaded”. This, however, didn’t work properly in some scenarios and filament could remain stuck between extruder Bondtech pulley and nozzle. This has been fixed.
• Improved behavior when removing the SD card: When SD card is inserted SD card menu is automatically shown. When SD card is removed menu which was active when the SD card was inserted is restored.
• Autoload disabled in extruder info (MK3) and sensor info (MK3S) menu: These menus serve for checking if the filament sensor works properly. The filament can be now inserted (without triggering load function) to check if sensor state changes.