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Prusa MK3S+ Maintenance

Regular maintenance checklist for the Original Prusa i3 MK3S+. If there is more than one MK3S+, go through the whole checklist for each printer. It follows Prusa's own guide: i3 Printer Regular Maintenance.

How often

Interval What
Every couple hundred print hours Cleaning, axes, belts, extruder, fans, sheets (sections 2 to 7)
Every 600 to 800 print hours, or at least yearly Electronics check (section 8)

Supplies

  • Prusa Lubricant (Prusa Lubricant Applicator Set). Acceptable alternatives per Prusa: Super Lube synthetic grease, GLEIT-ยต HF 400, Mogul LV 2-EP. Avoid very high viscosity grease.
  • Isopropyl alcohol (IPA) and paper towels
  • Compressed air, small brass brush, tweezers, cotton swabs
  • Allen keys, needle-nose pliers
  • Acetone (Smooth PEI sheet only)

Do not lubricate the Z-axis lead screws or trapezoid nuts. Prusa explicitly warns against this.

1. Before you start

  • Note the print hours from LCD > Statistics.
  • Unload filament.
  • Note the firmware version under LCD > Support (you will compare it in step 10).

2. General cleaning

  • Brush or vacuum filament bits, dust and broken supports from the frame and under the heatbed.
  • Heat the nozzle and brush off old plastic with a brass brush. Keep the brush off the thermistor and heater wires.

3. Smooth rods and bearings (X, Y, Z)

  • Roll each smooth rod between your fingers and feel for grooves or scratches. Note any damaged rods.
  • Wipe each rod clean with a dry paper towel.
  • Apply a thin film of Prusa Lubricant to each rod and run the axis end to end several times (Prusa maintenance tips guide).
  • If an axis still feels rough, remove the bearings, clean them with IPA, and grease the inside with a pea-sized amount (bearing maintenance article).
  • Check that the X-carriage-back screws and Y-bearing U-bolts are snug but not overtightened. Overtightening deforms the bearings and scratches the rods.

4. Belts and pulleys

  • Clear debris from the belt pulleys and idlers.
  • Confirm each pulley grub screw is tight against the flat of its motor shaft.
  • Pluck the X and Y belts: they should give a low bass note.
  • Check LCD > Support > Belt status. Target values are 260 to 290.
  • Adjust if out of range: Adjusting belt tension (MK4/S, MK3.9/S, MK3.5/S, MK3/S/+).

5. Extruder (Bondtech gears and idler)

  • Open the idler door (one screw on the MK3S+).
  • Cover the PTFE tube entry with a cotton swab, then clean both Bondtech gears with a brass brush, rotating a few degrees at a time through a full turn. Blow out the debris.
  • Verify the drive gear is aligned with the filament path and its grub screw is tight (Checking/re-aligning the Bondtech gear).
  • Confirm the idler shaft and bearing spin freely.
  • Optional: a tiny amount of non-oil grease on the outward-facing gear teeth only. Keep it off anything that touches filament.
  • Check idler screw tension: the head should be roughly flush with the extruder plastic (Idler screw tension).

6. Fans

  • Hold each propeller still and blow out dust with compressed air. Never spin a fan with air.
  • Remove plastic strings with tweezers.
  • Confirm the hotend fan and the print (part cooling) fan both spin freely by hand.

7. Print sheets

  • Clean each steel sheet with IPA; use dish soap and warm water for a deeper clean.
  • Acetone only on the Smooth PEI sheet, never on Textured or Satin (Flexible steel sheets guidepost).
  • Note any sheets with gouges or worn coating.

8. Electronics (every 600 to 800 hours, or at least yearly)

  • Power off and unplug the printer.
  • Inspect cables for pinching, rubbing or worn insulation, especially the heatbed cable bundle.
  • Blow dust out of the Einsy electronics enclosure.
  • Gently tug-test the PSU and heatbed power connectors, and retighten any terminal screws that move (Einsy RAMBo wiring reference).

9. Nozzle

  • Inspect the nozzle for wear (rounded tip, enlarged hole) or damage.
  • Replace it only if print quality stays poor after everything above (Changing or replacing the nozzle).

10. Firmware and slicer

11. Recalibrate

Prusa recommends recalibrating after maintenance.

  • Run Selftest from LCD > Calibration (fans, axes, heaters).
  • Run XYZ calibration if bearings, rods or the frame were disturbed (XYZ calibration MK3/MK3S). If the nozzle catches the paper, the SuperPINDA may need to be lowered slightly.
  • Run First layer calibration and set Live Z for each sheet in use (Basic calibration articles).
  • Print a small test part and inspect the first layer.

Afterwards

Record anything you found, what you did about it, and whether follow-up is needed. If the printer is not safe to use, tag it out of service: see Shop Safety: Tagging a Tool Out of Service and Reporting It.

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