Bambu Lab and Prusa calibration, step by step (2025)
The calibration order that actually makes sense. Flow, PA, input shaper, Z-offset — no fluff.
When a printer lands on the bench after a purchase or a big service, I always run the same sequence. Skip it and no benchmark will line up; you'll keep thinking the machine is faulty.
0. Mechanics first
No software calibration helps if a belt is slack or Z has play. On Bambu Lab check the rear eccentrics; on Prusa MK4 / MK4S the X and Y belt tension. Voron owners know the drill — quad gantry leveling.
1. Z-offset / first layer
Bambu Lab: run auto calibration, then verify with the purge line and the first-layer test plate in Bambu Studio. Prusa MK4S: load-cell calibrates cold but always verify hot.
2. Flow ratio (extrusion multiplier)
Print a single-wall calibration cube (0.4 nozzle = 0.42 line width). Measure the wall with a micrometer and tune flow to 0.42 ± 0.01 mm. This single step changes the look of your prints more than people expect.
3. Pressure Advance (Bambu / Klipper) or Linear Advance (Marlin / Prusa)
Print the PA pattern. Pick the value where corners are neither blobby nor hollow. Bambu Studio has it under Calibration. Prusa MK4 / MK4S ships with LA pre-tuned — only touch it for unusual materials.
4. Input shaper
Both Bambu and Prusa run it from the menu (Prusa from MK4 and MINI+). It removes corner ringing. On an older MK3S+ this is the main reason to switch to Klipper.
5. Temperature tower
Per filament. PETG 230–260 °C, PLA 195–225 °C, ABS 240–260 °C, PA-CF 270–290 °C. Pick the lowest temp where interlayer strength still holds.
6. Cooling test
Mainly for PLA and PETG. Details melting? More cooling. Delamination? Less. On Bambu P1S the auxiliary fan matters a lot — test both states.
7. Retraction / stringing
After flow and PA. Retraction towers or the stringing test in OrcaSlicer / PrusaSlicer. Direct-drive usually 0.4–0.8 mm, Bowden 3–5 mm.
This sequence takes ~90 minutes in the shop and runs around 1,200 CZK. Afterwards you have a printer that does what you expect. Stuck on a step? Ping me via the form.
Frequently asked questions
Always: mechanics → Z-offset → flow ratio → pressure / linear advance → input shaper → temperature tower → cooling → retraction. Skipping mechanics and flow is the #1 reason later calibrations don't line up.