Voron 2.4 and Trident: QUAD_GANTRY_LEVEL or Z_TILT_ADJUST fails or does not converge

Symptom

When levelling the gantry of a 2.4 (QUAD_GANTRY_LEVEL, QGL) or the bed of a Trident (Z_TILT_ADJUST), the process stops with an «out of bounds» error, fails because the probe is not reached in time, the adjustment of each motor grows instead of dropping to zero, or the readings spread too much. Afterwards the first layer comes out uneven.

Likely causes, from most to least likely

1. The gantry (2.4) or bed (Trident) starts badly tilted and the requested correction is out of range; in Klipper, QGL aborts if it exceeds max_adjust (4 mm by default).
2. The machine is not thermally stable: with a hot bed and chamber, the probe drifts during the first minutes.
3. Loose or uneven Z belts (2.4) or loose grub screws on the Z drives: probe spread increases.
4. Z motors wired to another driver or in a different order from the config: corrections diverge instead of converging.
5. On the 2.4, a badly squared gantry or Z joints that are too loose, giving tolerance or retry errors.
6. The probe reads unstably because of a mechanical or wiring problem.

Checks to tell which one it is

• Read the message: «out of bounds» means the starting tilt is too large; if the corrections do not drop towards zero on each pass, suspect the motor wiring.
• With the bed at 100 °C (and on the 2.4 the hotend at 150 °C), nozzle in the centre, run PROBE_ACCURACY: the ten readings must not trend up or down and the standard deviation should stay below 0.003 mm.
• Run STEPPER_BUZZ on each Z motor and check that the expected corner moves.
• On the 2.4, check that the four Z belts are reasonably tight and even.

Before you start

Before taking anything apart, cleaning or adjusting it, switch the printer off and unplug it, unless a step says otherwise, and do not touch the nozzle, the heater block or the bed until they have cooled down. If in any doubt about electricity, heat or moving parts, stop and ask a professional.

Step-by-step fix

1. Level by hand and try again

   If it fails with «out of bounds», disable the motors (M84), carefully move the gantry or bed by hand until it is roughly flat, run G28 and repeat QUAD_GANTRY_LEVEL or Z_TILT_ADJUST; it may take more than one pass. If it fails because the probe is not reached in time, first do a FIRMWARE_RESTART, level by hand as well as you can, G28 and retry.

   Check: On each pass the correction for each motor drops towards zero and the process finishes.

   If that does not fix it: If they diverge, check which motor goes to which driver (next step).

2. Check the Z motors and their order

   With STEPPER_BUZZ STEPPER=stepper_z (and z1, z2, z3) see which corner moves. Trident: stepper_z front left, z1 rear, z2 front right. 2.4: stepper_z front left, z1 rear left, z2 rear right, z3 front right. If it does not match, fix the config or, with the printer off and unplugged, the connectors. In Klipper, z_positions (z_tilt) and points (QGL) follow the order stepper_z, z1, z2…

   Check: Each motor moves its own corner and the levelling converges.

   If that does not fix it: Check the probe stability (next step).

3. Let the temperature settle

   Heat the bed to 100 °C (on the 2.4, also the hotend to 150 °C), leave the nozzle in the centre and run PROBE_ACCURACY. If the readings keep trending or the deviation is above 0.003 mm, wait another 5 minutes and repeat. According to Voron, a cold machine usually needs 10 to 20 minutes: note how long yours takes and wait that long before levelling.

   Check: PROBE_ACCURACY gives stable readings with a deviation below 0.003 mm.

   If that does not fix it: Check the Z belts and grub screws (next step).

4. Z belts, grub screws and probing speed

   With the printer off, check the grub screws on the Z drives. On the 2.4, leave the Z belts reasonably tight and even (Voron gives about 140 Hz over a 150 mm span as a starting point). If the probe still drifts, try lowering the probing speed (speed in the probe section of the config).

   Check: The standard deviation drops and levelling finishes without errors.

   If that does not fix it: On the 2.4, check the gantry squaring (next step).

5. Square the 2.4 gantry

   Square the gantry with the V2 Gantry Squaring guide, heat soak the chamber for at least an hour and a half and run QGL 3 to 5 times before fully tightening the Z joints while hot. If tolerance or retry errors appear after squaring, the Z joints may have been left too loose: tighten them a little more.

   Check: QGL converges within a few passes and the first layer comes out even.

   If that does not fix it: Check the probe as in the startup guide: ground, signal and voltage wiring, the voltage jumper if it has one, and the configured pin.

Prevention

• Always level with the machine hot and stable; on the Trident, run G28 Z after Z_TILT_ADJUST.
• Put QUAD_GANTRY_LEVEL or Z_TILT_ADJUST in PRINT_START after G28 and before BED_MESH_CALIBRATE.
• Check the Z drive grub screws from time to time and, on the 2.4, the Z belt tension.

Still not fixed?

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Printers it applies to

Voron Trident and 2.4.

Official sources

This guide summarises the official documentation linked here:

• Initial Startup · Voron Design
• V2 Gantry Squaring · Voron Design
• Secondary Printer Tuning · Voron Design
• Configuration reference (z_tilt y quad_gantry_level) · Klipper