Summary
New features and improvements
- First firmware release for the Prusa CORE One/+ INDX
- Full INDX toolchanger support, with automatic tool changes for up to 8 tools
- Contactless nozzle induction heating
- Continuous nozzle presence detection for safety and fault detection
- Contactless tool offset sensor
- Guided INDX calibrations: docks, tool offsets, nozzle cleaner, and more
- Automatic, low-waste nozzle cleaning with a wastebin
- Screen for unloading or changing all filaments at once
- Reworked tool mapping screen supporting up to 8 tools
- Empty Nozzle Cleaner
- Known issues are listed at the end
This is the first firmware release for printers equipped with the INDX toolchanger, and it builds on the current firmware. It adds complete support for the INDX hardware, including automatic tool changes with up to 8 tools, induction heating, and a guided calibration workflow that takes you from assembly to your first multi-material print.
Welcome, INDX!
The INDX toolchanger, developed by Bondtech in collaboration with Prusa Research, transforms your CORE One/+ into a multi-material printer with up to 8 tools. The system combines a single active INDX Head with lightweight passive tools. Each tool consists of a filament path and a nozzle, with no heaters, wires, or electronics. After installing the conversion kit and flashing this firmware, the printer identifies itself as a CORE One+ INDX and guides you through the initial calibrations.
Both the 4-tool and 8-tool kit configurations are supported. The firmware lets you calibrate and enable any number of tools from 1 to 8, so you can run the printer with exactly as many tools as your print requires.
Induction heating with temperature compensation
The INDX Head heats the nozzle of the currently picked-up tool by induction and measures its temperature contactlessly. In addition, the firmware runs a thermal compensation model that accounts for extrusion speed, chamber temperature, print fan speed, and the thermal properties of the loaded filament, keeping the actual melt temperature on target across changing print conditions. The INDX Head also independently monitors its own temperatures, adding an extra layer of safety on top of the printer's standard thermal protections.
Because the nozzles heat up in seconds, the time required for temperature stabilization is significantly shorter than on a conventional hotend.
New contactless tool offset sensor
The new inductive sensor mounted on the print bed automatically measures each tool's XY offset, ensuring that every tool prints in perfect alignment. The tools are heated during the measurement process, compensating for slight changes in the thermal expansion of the metal nozzle.
Continuous nozzle presence detection
For safe and reliable multi-tool printing, the INDX Head continuously verifies that the picked-up tool's nozzle is present. It detects the nozzle through its induction system and re-checks it approximately every 100 ms while idle and every 500 ms while heating.
If a nozzle goes missing - whether because a tool has fallen off its dock or a pick or park operation did not complete successfully - the printer detects the issue and responds safely instead of heating or extruding without a nozzle in place. Ambiguous readings, such as a nozzle caught halfway, are treated cautiously and resolved by the system's recovery logic.
Guided INDX calibrations
The Calibrations & Tests wizard has been extended with new INDX-specific routines and guides you through the complete setup process in the correct order:
- Homing calibration: Reworked for the INDX toolhead with improved accuracy and repeatability. Invalid probes are detected and retried automatically, and the calibration pattern has been redesigned, which is essential for repeatable tool docking.
- Dock calibration: Fine-tunes the position of each dock to ensure the INDX Head can reliably pick up and park tools.
- Tool offset calibration: Measures the XY offsets of every tool using the new contactless inductive sensor, ensuring all tools print in perfect alignment. This calibration, including Z-offset measurement, runs at the start of every print to eliminate tool-to-tool alignment issues.
- Nozzle cleaner calibration: Aligns the nozzle cleaner and wastebin positions for reliable cleaning and blob ejection.
- Input Shaper and Phase Stepping calibration: Measures vibration compensation using the accelerometer built into the INDX Head.
Automatic, low-waste nozzle cleaning
The printer keeps every nozzle clean automatically. An integrated nozzle cleaner and wastebin handle a range of routines, from a quick wipe during tool changes to deep cleaning and purged-blob ejection, ensuring that color bleed and debris never reach your print. The entire system is designed around minimal waste: tool changes require only a very small purge, and the purged material is collected in the wastebin rather than ending up on the print bed or in a separate purge tower.
Empty Nozzle Cleaner
Allows you to easily empty the wastebin. It can automatically pause prints with a high number of tool changes (configurable under Settings > Nozzle cleaner).
A side filament sensor for every slot
Each tool slot has its own side filament sensor, allowing the printer to detect filament runout on a per-tool basis, which is essential for multi-material printing. A runout event triggers the standard filament-change process for the affected tool only.
New multi-tool filament management screens
Managing up to 8 filaments simultaneously is now easier:
- The filament change screen for multiple tools now offers "Set all to" to assign a filament type to all slots at once, and "Unload all" to clear the printer in a single operation.
- Unloading works even when the loaded filament type is unknown.
- Loaded filaments can be reviewed per slot, including nozzle diameter and high-flow nozzle settings for each tool.
Tool mapping and Spool Join
The features known from the Original Prusa XL are available here as well:
- Tool mapping lets you reassign which physical tool prints each filament from the sliced G-code, directly from the extended tool mapping screen on the printer or remotely via Prusa Connect. The screen is now scrollable to accommodate mapping of up to 8 tools.
- Spool Join automatically continues printing from another slot loaded with the same filament when a spool runs out.
Known issues
Pick / park failures
The INDX toolchanger can perform thousands of tool changes during a single print, and reliable picking and parking depend on accurately calibrated positions. If a pick or park operation fails, the printer automatically re-homes the tool and retries, which usually succeeds. In rare cases (for example, if a tool has fallen off its dock), multiple consecutive failures will pause the print for inspection. Once the print area has been checked, printing can be resumed seamlessly.
Parking in an occupied dock
In rare cases, the INDX Head may fail to park a tool while still passing the subsequent nozzle-presence check. The previously used nozzle may then continue printing until the system detects the issue.
Single-tool auto-load
Filament auto-load is supported, but currently only for the tool that is picked up.
Flexible materials
In some cases, TPU and other flexible filaments can tangle inside the INDX Head, causing the extruder motor to skip steps. We will continue fine-tuning the system to eliminate this issue.
Special materials
The thermal model uses thermal-capacity constants defined for known filament types. Special materials with different thermal properties may trigger a thermal runaway error.
Spontaneous INDX Head resets
The INDX Head may undergo internal resets, even during printing. This has no negative effect on print quality, but in rare cases side-effect errors ("Puppy errors") may occur. We are actively working to resolve this.
Phase Stepping & Input Shaper calibrations
These calibrations may occasionally encounter errors. In most cases, restarting the printer and trying again resolves the issue.
Filament stuck detection
Not available on INDX printers in this release.