Bambu P1S nozzle change: step-by-step guide and what not to skip

Changing the nozzle on a Bambu P1S is one of the few maintenance jobs the printer actually makes straightforward — mostly. There is one step that catches most people out, and if you miss it you end up with a slow melt leak that carbonises inside the hotend and is much harder to fix than the original problem.

When the nozzle actually needs changing

Before you reach for the wrench, it is worth confirming what you are dealing with. A clog and a worn nozzle feel similar but they are different problems.

A clog shows up as under-extrusion, gaps in layers, or filament that stops feeding mid-print. If you have only been running PLA or PETG through a brass nozzle, a cold pull or a short filament flush usually clears it without touching the nozzle at all.

A worn nozzle builds up slowly. Surface quality drifts downwards, lines become inconsistent, and fine detail gets fuzzy. Abrasive materials — carbon-fibre PETG, glass-filled nylon, any filament with metallic particles — will wear brass noticeably within a single spool.

You might also be changing nozzle size: 0.6 mm for faster, rougher parts, or 0.2 mm for fine detail work.

Brass or hardened steel?

The stock nozzle is 0.4 mm brass. Brass is the right choice for the materials Bambu ships sample rolls of: PLA, PETG, TPU. It machines to a precise bore, has low friction, and keeps filament flowing smoothly.

If you are running anything abrasive — CF-PETG, PA-CF, or any glass-filled material — you need hardened steel. A brass nozzle will start to show visible wear after 1-2 kg of carbon-fibre filament. Hardened steel costs a little more and typically needs the extrusion temperature set 5-10 °C higher to compensate for its lower thermal conductivity, but it lasts far longer.

Bambu sells their own nozzles for the P1S/P1P/X1 family. Third-party options are widely available too — just make sure whatever you buy is listed as compatible with the Bambu hotend. Generic MK8-pattern nozzles will not fit.

What you need

The nozzle wrench from the Bambu toolkit (it came in the box), a replacement nozzle for the P1S hotend, and some awareness that the heater block will be around 220-250 °C during the swap. Heat-resistant gloves are sensible. A small piece of cardboard or foil underneath to catch molten drips is useful but optional.

That is genuinely all you need. No torque wrench, no heat gun.

How to change the nozzle

The P1S nozzle is changed hot. You heat the hotend first to soften any residual filament so the nozzle unscrews cleanly. Do not try to force it cold — you will likely strip the aluminium threads in the heater block.

1. On the P1S touchscreen, go to Device > Toolhead and select the nozzle replacement option. The printer will home, move the toolhead to a comfortable working position, and begin heating automatically.

2. Wait for the hotend to reach temperature — typically around 220 °C, higher if you were last running ABS or nylon. Let it stabilise before you touch anything.

3. The printer will prompt you to purge a short burst of filament to clear the melt zone. If it does not prompt you, manually extrude 20-30 mm from the touchscreen.

4. Slide the silicone sock off the heater block and set it somewhere safe. It goes back on at the end.

5. Fit the nozzle wrench on the flat section of the nozzle and turn anti-clockwise. Use a firm, steady pull rather than a sharp jerk. There will be some initial resistance, then it should unscrew freely.

6. Lift the nozzle clear carefully. Have your cardboard underneath to catch any drips.

7. Thread the new nozzle in by hand first, turning clockwise. Get it finger-tight only at this stage.

8. Tighten with the wrench while the hotend is still at temperature. This is the step to pay close attention to — see the section below.

9. Refit the silicone sock.

10. Let the printer cool fully, then run a flow calibration before your first print with the new nozzle.

The hot-tightening step

This catches most people coming from other printers. On budget FDM machines the nozzle seats against a PTFE tube or a separate heat break, so cold-tightening works fine. The Bambu P1S hotend is a different design — the nozzle seats directly against the heater block. When you tighten cold and then heat up, the metals expand at different rates and the joint loosens slightly. That small gap is enough for molten filament to creep up the threads, carbonise, and eventually cause a blockage that is far harder to clear than a routine nozzle swap.

Tighten the nozzle firmly while the hotend is still at printing temperature. Snug and secure — not maximum force. The heater block threads are aluminium and will strip if you overtighten.

How often should you change it?

For PLA and PETG through brass: most people get 3-6 months of regular printing, or roughly 5-10 kg of filament, before quality starts to visibly drop. If you print every day, check sooner.

For abrasive materials through brass: do not wait to see the wear. Switch to hardened steel straight away.

Hardened steel nozzles last much longer — often a year or more depending on how much abrasive material you run through them.

Does changing the nozzle affect the warranty?

The nozzle is a consumable part. Bambu Lab designs the P1S for user-serviced nozzle replacement, so swapping it will not void your warranty. Where it gets more complicated is if something goes wrong during the swap — a cracked heater block or stripped thread is damage from the procedure, not a manufacturing defect. Work carefully and it should not be a problem.

What to check on the first print

Before loading a long job, run Bambu's built-in flow calibration or a short test print first.

Look for:

• Filament oozing or bubbling at the base of the nozzle where it meets the heater block — this means the nozzle is not tight enough. Heat it back up and tighten it before the leak has a chance to carbonise.
• Consistent line width matching what you expect for the nozzle size.
• Normal first-layer adhesion.

A new nozzle — even one that is nominally the same size — will have slight manufacturing variation. Running flow calibration after a nozzle change saves a lot of wasted material on the first real print.

When to mail it in

If the nozzle swap went fine but you are still seeing under-extrusion, poor layer adhesion, or inconsistent lines afterwards, the issue is probably further up the hotend — a partial blockage in the heat break, a degraded PTFE liner, or a failing thermistor. Those faults need spare parts and more disassembly than most home setups can handle comfortably. If you would rather skip the maintenance entirely and just get your parts made, our 3D-printing service covers everything from one-off prototypes to small production runs. Upload your file, get a quote, and we take it from there.