Lubricating lead screws, rods and rails: with what, how often and where not to put it

Symptom

The axes squeak or sound dry, the toolhead or the bed moves with more resistance than before, the Z axis is noisy going up or layer marks start to appear; or maintenance is due and you do not know which lubricant to use or where.

Likely causes, from most to least likely

1. Dry lead screws and rails, or old dirty grease: friction and wear increase, noises appear and the movement stops being smooth (Bambu Lab).
2. Too much lubricant: Elegoo warns that the excess attracts dust and particles and turns into dirt.
3. The wrong or mixed lubricant: Bambu Lab uses grease for lead screws and oil for linear guides, rails and steel shafts, and asks you not to mix them up.
4. Lubricating where the maker forbids it: Bambu Lab allows no grease or oil on the X-axis carbon rods of the X1 and P1, Creality wants no grease on carbon rods, and Prusa wants no lubricant on the Z lead screws or nuts of the MK4/S and MK3.9/S.
5. Overdue maintenance: Bambu Lab checks lead screws every three months, Creality every 300 printing hours on the K1C and Elegoo every two months on the Neptune 4.

Checks to tell which one it is

• Look in your printer's manual for which parts are lubricated, with what and how often: it overrides any general advice.
• With the printer off, move the axes by hand: a tight spot or rough rubbing means dirt or lack of lubrication.
• Check whether the lead screws and rails have dark grease, dust or filament debris on them.
• Identify what each axis of your printer uses: lead screws (threaded rods), smooth rods, linear rails or carbon rods.

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. Switch off, unplug and clean

   Switch off and unplug the printer before starting (Elegoo). Clean the old grease and dust off the lead screws and rods with a lint-free cloth: Bambu Lab wraps it around the rod and runs it up and down, and Creality uses isopropyl alcohol for the rods.

   Check: The parts are clean, with no dark grease or debris.

   If that does not fix it: If you see scratches or a damaged rod, ask the maker before lubricating.

2. Grease on the lead screws, if your maker says so

   Apply a thin, even layer of grease to the lead screw: Bambu Lab uses its own grease or equivalents such as a white lithium grease or a silicone one, and Elegoo uses white lithium grease applied with a cotton swab. Do not do it if your manual forbids it: Prusa wants no lubricant on the Z lead screws or nuts of the MK4/S and MK3.9/S.

   Check: The lead screw has a thin film, with no lumps.

   If that does not fix it: Spread the grease and remove the excess (step 4).

3. Oil or light grease on rails and smooth rods

   On linear guides, rails and steel shafts, Bambu Lab uses oil; Prusa lubricates smooth rods and bearings with a small amount of its lubricant or a general-purpose lithium grease. Nothing on the X-axis carbon rods of Bambu Lab X1 and P1 printers, and no grease on the carbon rods of the Creality printers that have them. On the A1 Y axis, Bambu Lab allows the original WD-40 Multi-Use Product and no other WD-40 product.

   Check: The toolhead or the bed slides smoothly from end to end.

   If that does not fix it: Spread the lubricant (next step).

4. Spread it and remove the excess

   Switch the printer on and move the axis from end to end several times from the screen to spread the lubricant (Bambu Lab, Creality, Elegoo). Then wipe off the excess, especially near the lead screw nuts: extra grease attracts dust and dirt (Creality, Elegoo).

   Check: The axis moves quietly and there are no lumps left.

   If that does not fix it: If what squeaks is a pulley, see the next step.

5. Squeaking pulleys

   Creality explains that idler pulleys have sealed bearings that need no lubrication: only if they squeak, put a little silicone lubricant on the top and bottom of the pulley, and nothing if they do not, to avoid collecting dust. Bambu Lab uses grease to remove noise between belts and idler pulleys.

   Check: The squeak is gone.

   If that does not fix it: If it persists, check the tension and condition of the belt and the pulley.

6. Put it in the calendar

   Check and lubricate at your maker's interval: Bambu Lab every three months; Creality every 300 printing hours on the K1C, rods included; Elegoo every two months on the Neptune 4; Prusa checks axes, pulleys and belts every 200 hours on the MK4. If you print a lot of ABS or ASA, Creality suggests cleaning the X axis every 5 kg.

   Check: The next check is in your calendar.

   If that does not fix it: Bring it forward if the noises come back.

Prevention

• Use only the lubricant your maker specifies, and sparingly.
• Do not mix oil and grease: each has its place.
• Always clean off old grease and dust before applying new lubricant.

Still not fixed?

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Printers it applies to

Any FDM (filament) 3D printer, from any brand.

Official sources

This guide summarises the official documentation linked here:

• Lubricant Grease and Lubricant Oil · Bambu Lab
• Please lubricate the Z-axis lead screw (Z-axis maintenance) · Bambu Lab
• K1C/K1C 2025 Maintenance Tips · Creality
• Lead screw Routine Maintenance (Neptune 4) · Elegoo
• Regular printer maintenance (MK4/S, MK3.9/S) · Prusa Research
• Layer shifting (lubricating smooth rods) · Prusa Research