After installing the INDX on your Prusa CORE One/+, the selftest will check the printer's assembly, wiring, and electronic components. It is the first part of the Calibration Wizard, which is prompted automatically when you turn on the printer for the first time or after a factory reset. After the initial calibration is completed, each step of the selftest can be initiated under LCD Menu -> Control -> Calibrations & tests.
Note that if the printer is placed on an unstable surface or if another 3D printer is running next to it, it may negatively affect the calibration. The printer should be placed on a stable surface.
Calibrations & Tests
- Door sensor
- X axis test
- Y axis test
- Z alignment calibration
- Belt tuning
- Homing calibration
- Dock calibration
- Loadcell test
- Z axis test
- Fan test
- Heater test
- Tool offset calibration
- Nozzle cleaner calibration
- Filament sensor calibration
- Phase stepping calibration
- Input shaper calibration
Door sensor
If the sensor behaves differently from what is expected in the door sensor calibration, check whether the sensor is working. Go to the LCD menu to Info -> Sensor Info -> Door Sensor. Then, try opening and closing the door and see if the sensor is triggered. If the door does not trigger the sensor, try it by pressing the latch with your finger.
If the sensor shows the correct status, go back to the calibration by going to Control -> Calibrations & tests -> Door sensor, and follow the instructions to tighten or loosen the screws.
On the last part of the calibration, the printer prompts you to place your fingers between the door and the frame. This is meant to prevent injury. If there is an issue with this test, you can keep the door completely open to pass.
If the door sensor does not work, check the cable for damage and the connection.
X and Y axes test
This part of the selftest measures the axis length and motor load.
In case of an issue on the X-axis or the Y-axis, make sure that there is no obstacle to the movement, and readjust the belt tension.
Also, test the printer movement with the stepper motors temporarily disabled (LCD Menu -> Control -> Disable Motors), moving along both XY diagonals.
If the issue persists, look through the openings on the plastic parts under the CoreXY motors. You will be able to see the motor pulleys. Make sure that they are in the correct orientation, that both set screws are firmly tightened, and that one of them is tightened over the flat part of the motor shaft.
 |  |
| Y-motor pulley | X-motor pulley |
Z alignment calibration
This part of the calibration will move to align the three motors on the Z axis so that the heatbed is level. In case of any errors on this test, check the trapezoidal nuts on the motor threaded rods. For that, move the bed all the way down either by the LCD menu in Control -> Move axis -> Move Z, or by turning the threaded rods on the Z motors. Unscrew and remove the screws indicated in the image below. Move the nut along the threaded rod and see if the movement is smooth or not. When the trapezoid nut is still loose, try moving the motor threaded rod by hand (the printer needs to be powered off for that), and see if it turns easily.
 |  |  |
| Left side trapezoidal nut | Rear motor trapezoidal nut | Right side trapezoidal nut |
Check also that the spacers are correctly installed.
 |  |  |
| Left spacer | Rear spacer | Right spacer |
Belt tuning
The LCD menu will guide you through the belt wizard. If one of the sides shows a gap, do the following procedure:
- Loosen the belts completely. Be careful so that the square nuts do not fall off the plastic parts when removed.
- Check which side sits against the back end (tight side) and which one has to be pushed towards it to touch it (loose side).
- Put a universal wrench or anything with a similar thickness between the tight side and the back end. Slightly pull the loose side to correct the skew.
- Check the alignment again and repeat if needed. In case the tight and loose sides switched, repeat the process from the other side, but apply a smaller amount of pressure.
- Tighten the belts again.
- Move the toolchanger around the Y and X axes by hand to even the belt tightness.
Homing calibration
If there are issues with the homing calibration, check the X and Y axes and the homing calibration again.
Dock calibration
This calibration will test each dock. If a specific dock fails, try:
- Tightening the dock screws further.
- Make sure that the toolchanger is fully pushed into the dock when requested.
- Redo the belt tuning and the homing calibration.
Loadcell test
A functioning loadcell is fundamental to detect that the nozzle is close enough to the steel sheet for printing, and to avoid damage that would be caused by the nozzle digging into the steel sheet.
Make sure that the surface the printer is on is as stable as possible: any form of vibration propagated to the surface under the printer, or a not fully stable surface under the printer, might cause a false reading on the loadcell, causing it to fail the selftest.
Check also if the main cable is properly connected to the toolchanger.
Z axis test
Check if there is anything blocking the path of the Z axis. It may be something stuck in the threaded rods or anything on the floor of the chamber.
Fan test
This part will test all fans in the printer. The RPM values for the fans need to be within these values for the test to pass:
- Print fan: 4800 - 6799 RPM
- Dock fan: 4800 - 6799 RPM
- Hotend fan: 12000 - 18000 RPM
- Chamber fan: 7225 - 9775 RPM
- Filtration fan: 2890 - 3910 RPM (for printers with the Advanced Filtration System)
If there is an error shown, first define which one of the fans has the issue.
The hotend fan is not accessible. To test it, go into the LCD menu to Control -> Temperature -> Nozzle, and set the nozzle to any temperature above 50 ºC. Check if you can hear the fan spinning. Then, go to the LCD menu in Info - Sensor Info - Fan Info, and check the hotend fan RPM.
If any of the other fans do not pass the test, check:
- Check for any obstruction that could prevent the fan from spinning. Particularly on the print fan, check if the cable is not going into the blades.
- Make sure that they are connected correctly to the electronics board.
- Go to the LCD menu in Control -> Temperature, and set the fan to be tested to 100%. See if the fan spins or if it shows any errors.
Heater test
The selftest can determine a fault during the heating of a component, and the affected component.
Heat the affected component under LCD Menu -> Control -> Temperature, heat up the part that failed the selftest, and see if any error appears. If it does, the error should have a QR code that redirects to the article that describes how to troubleshoot that particular error.
Tool offset calibration
If the tool offset calibration fails, check if all the nozzles are positioned correctly and the nozzle tips are clean.
Then, check the offset sensor for the following:
- The Prusa logo is facing up
- The cable is properly connected
- The board is secured
Also, try to redo the homing calibration.
Nozzle cleaner calibration
This calibration is a measurement and should not give any errors. In case the printer can't complete these tests, check the axes again.
Filament sensor calibration
The INDX has a side filament sensor. If the calibration fails, check the following:
- The 5x2 magnets are inserted and tightened
- The 7x8 magnets are in the correct orientation
- There is no filament debris in the filament sensor in the sensor case
Phase stepping calibration
For this test, make sure that you are not touching the printer and that no other printers are running on the same surface as the CORE One INDX. You can read more about it here: Phase Stepping (CORE One).
Input shaper calibration
After this calibration, the printer will show you the Input shaper frequency values. The lower limit is 35 Hz, and the upper limit is 70 Hz. If the value is too low or too high, check the belt tightness and the assembly.