Photon Mono M5s: leveling, resin, layer or dropped-print monitoring warnings

Symptom

The Photon Mono M5s monitors the print with a pressure sensor and stops with a warning: «Leveling monitoring error», «Resin monitoring error», «Layered monitoring error» (part of the print has broken off) or «Drop bottom monitoring error» (the print, or part of it, has fallen into the vat). Sometimes «Mechanical detection failed» appears.

Likely causes, from most to least likely

1. Dropped print: at the zero position the platform is too far from the film (insufficient leveling) or the film is loose.
2. Weak adhesion settings: short bottom exposure or too few bottom layers, too short a Z lift or too fast a lift speed.
3. Not enough supports, unsupported overhangs or sudden changes in cross-section.
4. Too little resin in the vat, or cold resin: according to Anycubic, about 23 °C is ideal; between 10 and 20 °C it cures less well and below 10 °C it does not solidify.
5. The pressure sensor or its cables are loose or damaged (leveling or sensor warnings).
6. The sliced file is faulty.

Checks to tell which one it is

• Note the exact warning shown on the screen.
• If it is about resin, check that there is enough resin in the vat.
• Open the sliced file on the computer and step through the layers: look for odd images and, with Photon Workshop's island check, red areas (unsupported) or yellow ones (possible overhang).
• Print the official test file: if it also fails, the problem is the machine, not your file.

Before you start

Uncured resin irritates skin and eyes: wear nitrile gloves and safety glasses, ventilate the room and do not look at the UV light. Before taking anything apart or cleaning it, switch the printer off and unplug it, unless a step says otherwise. If in any doubt, stop and ask a professional.

Step-by-step fix

1. Resin and temperature

   Wearing nitrile gloves and safety glasses, and with ventilation, add enough resin before starting. Print with the resin and the room close to 23 °C, the ideal temperature according to Anycubic.

   Check: The resin warning does not return and the layers cure properly.

   If that does not fix it: Check the leveling and the film (next step).

2. Leveling and vat film

   If it is your first print or the part falls off, level again following the M5s manual or video and print the test file from the USB drive. If you replaced the film yourself and it has ended up loose, tighten its screws.

   Check: The test print stays stuck to the platform.

   If that does not fix it: Adjust the adhesion settings (next step).

3. Adjust the slicing settings

   As a starting point, Anycubic suggests adding 10 s to the bottom layer exposure and 5 more bottom layers on top of your previous values, and more for large, heavy parts. Check that the Z lift is sufficient and leave the lift speed at the slicer's default.

   Check: The print neither comes off the platform nor stays on the film.

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

4. Supports and orientation

   Add supports or increase their density and contact depth, especially on overhangs. Rotate the part to avoid sudden changes in cross-section between layers and use Photon Workshop's island check to see unsupported areas.

   Check: No red areas remain in the island check and the layer warning does not return.

   If that does not fix it: Check the exposure and the file (next step).

5. Exposure and file

   Check that the exposure time is not far from the one recommended for your resin. Open the sliced file on the computer and check layer by layer that the images match the part; if in doubt, slice it again.

   Check: The file looks correct and the part prints without warnings.

   If that does not fix it: Check the pressure sensor (next step).

6. Check the pressure sensor

   For leveling or sensor warnings: switch off and unplug the printer, move the platform to mid-height, unscrew its nut and remove it. Remove the cover of the Z-axis arm, undo the four pressure sensor screws and reseat its two wires on the adapter board; then remove the back cover and reconnect the sensor wires on the mainboard.

   Check: At power-on, the leveling or sensor warning no longer appears.

   If that does not fix it: If «Mechanical detection failed» appears or the warning persists, open a ticket with Anycubic support. Meanwhile you can dismiss the warning from the screen: the printer uses the last saved leveling point but stops monitoring resin and leveling.

Prevention

• Keep the resin and the room close to 23 °C and do not print cold.
• Check supports and overhangs with the island check before printing.
• If you replace the film, make sure it is taut and its screws are tight.

Still not fixed?

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Printers it applies to

The Anycubic Photon Mono family: Photon Mono 4, Photon Mono 4 Ultra, Photon Mono M5s, Photon Mono M7, Photon Mono M7 Max, Photon Mono M7 Pro and Photon Mono X 6Ks.

Official sources

This guide summarises the official documentation linked here:

• Photon Mono M5s: Drop bottom monitoring error · Anycubic
• Photon Mono M5s: Leveling monitoring error · Anycubic
• Photon Mono M5s: Resin monitoring error · Anycubic
• Photon Mono M5s: Layered monitoring error · Anycubic