Summary
- MK3.5 introduction
- Firmware flashing
- Upcoming features
- Deprecated features
This is the first public GitHub release of the firmware for the Original Prusa MK3.5 3D printer. Make sure to read all the information provided below before you upgrade your printer to MK3.5.
MK3.5 introduction
The MK3.5 kit enables you to upgrade your MK3S and MK3S+ with plenty of new and useful features. You will get 32-bit electronics along with a new LCD, as well as Wi-Fi and LAN connectivity with support for remote print management via Prusa Connect. Last, but not least, the printing speed will be significantly faster thanks to Input Shaper and Pressure Advance support.
To learn more about MK3.5, please follow this link
Firmware flashing
Although the MK4 and MK3.5 share the same xBuddy motherboard, their firmware is distributed separately. Once you boot the printer up, the system will check for the hardware configuration and in the case it detects the MK3.5, it will ask you to insert the bundled USB flash drive with the MK3.5 firmware on it, reboot the printer, hit the knob once and install it.
The same firmware can be downloaded from under these release notes.
Attention: Don't try to run the MK3.5 with MK4 firmware and vice versa. Both printers utilize different sensors (e.g. Loadcell vs SuperPINDA) and this might lead to damage to your printer.
Upcoming features
The Original Prusa MK3.5 firmware 5.2.0 is perfectly capable of printing, running wireless connection and utilizing remote control via Prusa Connect. However, there are some features, mostly for advanced users, which will be added later on.
Here is a list of the upcoming features:
Adjustable mesh bed leveling
The mesh bed leveling (MBL) is already part of the firmware and is performed before each print to ensure a good, consistent first layer. However, the MK3S/MK3S+ allowed you to change the MBL parameters like:
- the size of the Mesh (3x3, 7x7, 9x9)
- the number of Z-probe (1x, 3x, 5x)
- compensate for the heatbed magnets (ON/OFF)
These extra parameters will be added in future firmware releases.
Thermal model calibration
Last year we introduced another safety feature to further improve the security of the MK3 family of printers. You can learn more about it in this article. This feature is currently under development for the 32-bit firmware which runs on the MK3.5.
You can, however, run the MK3.5 without any worries. There are already multiple sensors and firmware watchdogs ensuring the printer's safety.
Bed level correction
Before the printers are shipped from our factory, each part is inspected for quality. Namely, the Y-carriage, heatbed, and frame are inspected for tolerances to ensure the print surface is perfectly flat. As a result, the majority of the printers should be fine without any need for adjustment by the user.
However, in some cases, there might be a need to compensate for even the slightest imperfections in the first layer. The bed level correction allows you to adjust the heatbed corners in software - i.e., raise or lower the heatbed on the Left, Right, Front and Back sides. This feature is also under development and will be added in the upcoming firmware release.
PID calibration
PID calibration (tuning) is a calibration procedure for advanced users that ensures the printer holds a stable target temperature at all times. Most of the Prusa printers with stock hotend should be working without any need for calibration.
However, we are aware that this feature might be needed in case of third-party hotends, therefore the developers are already working on finalizing the PID implementation.
E3D REVO hotend
As of now, there might be issues with running the REVO hotend produced by the company E3D on the MK3.5. While testing this configuration, we discovered that due to the strict checks built into the firmware, the initial self-test will fail.
It is possible to start the print, however, we recommend waiting for the upcoming release, which will extend the support for 3rd party hotends.
OctoPrint
Transferring the code responsible for supporting OctoPrint from the MK3S/MK3S+ to the MK3.5 firmware isn't possible due to the different system-on-chip (SoC) architecture. Therefore the developers had to start from scratch and the MK3.5 is now capable of printing using OctoPrint same as XL and MK4.
However, there are still some features that we are looking into, for example, while connected to Octoprint, only the logo is displayed on the printer's screen and all actions (e.g. start/pause/cancel print) have to be done in the web interface.
As an alternative we recommend trying Prusa Connect, which allows remote printing and together with Prusa Slicer enables seamless G-code streaming into the printer.
Print sheet profiles
With the MK3.5, you can save profiles for multiple print sheets. Just like the MK3S/MK3S+, once you've saved two or more sheet profiles, a new toggle will appear in the printer's menu, allowing the user to switch quickly between the sheet profiles. The only existing limitation is the inability to rename the sheets, this will be addressed in the future release.
Deprecated features
Belt test
The belt test originated a few years ago in the 8bit firmware allowing you to verify whether the belt tension is set in the optimal range for your MK3S/MK3S+. In the case of the MK3.5, this feature will be replaced with an online belt tuner available at prusa.io/belt-tuner, which can be accessed from your laptop, tablet or phone.
Linear advance
The MK3S/MK3S+ utilizes Linear Advance (LA) which predicts the pressure build-up in the extruder when printing at higher speeds. The firmware of the printer uses that prediction to decrease the amount of filament extruded just before stopping and decelerating, which prevents blobs or artifacts at the sharp corners.
With the MK3.5, this feature is no longer needed as it is replaced with Input Shaper & Pressure Advance achieving even better print results.
XYZ calibration
This feature dates back to the old days of the MK2 platform, where the printer's frame was susceptible to a certain degree of skew and XYZ calibration helped you to align it back.
Starting with the MK3, the frame became more rigid and perpendicular by design and with further improvements in the 32-bit firmware there is no need to keep this feature anymore.