Getting Great Prints on the Prusa MK4S
The MK4S is Prusa's current flagship bedslinger: open-frame, no auxiliary fan, but with the input-shaping-capable board and sensing (loadcell first-layer calibration, filament sensor) that make it one of the most self-correcting open printers available.
Is the Prusa MK4S enclosed?
Enclosure: No. Auxiliary part-cooling fan: No.
No enclosure and no auxiliary fan means the MK4S plays by open-printer rules for warping-prone materials — its sophistication is in consistency and automatic calibration, not in chamber-assisted material range. ABS/ASA/PA/PC still need an owner-built enclosure to compete with a Bambu X1C or QIDI machine on those materials.
Baseline settings for Prusa's Prusa MK4S profile
Prusa publishes one shared filament-profile baseline across its OrcaSlicer-family lineup rather than a separate one per model, so these are the numbers the Prusa MK4S starts from — use them as the floor and calibrate flow/retraction per spool:
| Material | Nozzle | Bed (textured/hot) | Fan max |
|---|---|---|---|
| PLA | 220 °C | 60 °C | 100 % |
| PETG | 240 °C | 85 °C | 90 % |
| ABS | 260 °C | 105 °C | 80 % |
| TPU | 240 °C | 35 °C | 100 % |
Where the MK4S's extra sensing helps — and where it doesn't
Loadcell first-layer calibration removes most manual leveling error, but it can't compensate for a genuinely warped or debris-covered sheet. If first layers are inconsistent despite a fresh calibration, check the sheet surface before adjusting Z-offset further. See the first-layer calibration guide.
ABS/ASA still needs a tent. The board's sophistication doesn't add chamber heat. Build or buy a simple enclosure if ABS/ASA is a regular material, and follow the open-printer values in the warping guide.
The filament sensor catches runout, not moisture. A spool can be wet and still feed perfectly normally as far as the sensor is concerned; don't let a clean filament-sensor report talk you out of drying a spool that's stringing. See the drying guide.
Symptoms this machine's form factor is prone to
Without a chamber, the Prusa MK4S inherits the classic open-printer failure modes in full: warping and adhesion loss on hot materials, and higher sensitivity to room drafts than any enclosed machine has to deal with:
- Warping and bed adhesion — the two symptoms an enclosure would otherwise mitigate.
- First-layer problems — open frames are more exposed to bed-leveling drift from handling and transport.
- Ghosting and ringing — lighter open frames typically need more belt-tension attention than an enclosed cube at the same speed.
A sane first-print checklist
- Match the plate/surface selection in the slicer to what's actually on the bed, if the machine supports more than one build surface. Mismatches are the leading cause of "it should have stuck" reports.
- Run a flow-ratio calibration on any filament that isn't the exact spool Prusa's profile was written against. Off-brand and generic spools routinely land several percent off the stock flow ratio; that shows up as over- or under-extrusion that looks like a hardware problem but isn't.
- Change one variable per test print. Temperature, fan speed and retraction all interact; the fastest way to a dialed-in Prusa MK4S is small, single-variable tests read one at a time, not three changes at once.
For the full Prusa lineup and its common failure modes, see the Prusa troubleshooting hub.
Frequently asked questions
Can the Prusa MK4S print ABS and ASA without an enclosure?
Not reliably. The MK4S is open-frame with no auxiliary fan, so it plays by open-printer rules for warping-prone materials: ABS, ASA, PA and PC still need an owner-built enclosure to compete with enclosed machines like a Bambu X1C or a QIDI. Its strength is consistency and automatic calibration, not chamber-assisted material range.
What baseline temperatures does the Prusa MK4S profile use?
Prusa's shared filament baseline for the MK4S runs PLA at 220 °C nozzle and 60 °C bed (fan 100 %), PETG at 240 °C and 85 °C (fan 90 %), ABS at 260 °C and 105 °C (fan 80 %), and TPU at 240 °C and 35 °C. Use these as the floor and calibrate flow and retraction per spool, especially for generic filament.
Does the MK4S loadcell calibration fix all first-layer problems?
No. Loadcell first-layer calibration removes most manual leveling error, but it cannot compensate for a genuinely warped or debris-covered sheet. If first layers stay inconsistent despite a fresh calibration, check the sheet surface before adjusting Z-offset further. Similarly, the filament sensor only catches runout — a wet spool feeds normally, so dry filament that strings regardless of a clean sensor report.
Want these numbers turned into a personalized fix list for your Prusa MK4S?
Answer five quick questions about your printer, filament and build plate, and our rule engine turns them into a prioritized fix list with exact slicer values — the same knowledge these guides are written from.
Get a personalized fix list in 2 minutes — free Works with Bambu Studio, OrcaSlicer, PrusaSlicer and Cura. No account needed.Sources
- OrcaSlicer vendor profiles — SoftFever/OrcaSlicer (GitHub)