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Prusa Research
Prusa Research Original Prusa MK3.9S
FDM filament printer.
Assessed from documentation Updated on October 4, 2026
How to recognize it: Check the full model name “Original Prusa MK3.9S” on the label or in device information. Suffixes and revisions identify different models; check the source before selecting parts.
Technical specifications
Manufacturer specifications for the listed configuration. Notes identify accessories, measurement conditions and calculated values.
Technology and structure2
| Technology | FDM |
|---|---|
| Build area shape | Rectangular |
Build area and volume4
| Build area X | 250 mm |
|---|---|
| Build area Y | 210 mm |
| Build area Z | 220 mm |
| Build volume | 11.55 L Calculated from nominal X × Y × Z dimensions. |
Hardware1
| Extruder type | Direct drive |
|---|
Features4
| Colors with documented configuration | 5 With optional MMU3. |
|---|---|
| Automatic leveling | Yes Loadcell sensor. |
| Filament runout sensor | Yes |
| Power loss recovery | Yes |
Connectivity2
| Control display diagonal | 3.5 in |
|---|---|
| Connectivity | Ethernet, Wi-Fi, NFC, USB |
Dimensions and weight4
| Machine width | 500 mm |
|---|---|
| Machine depth | 550 mm |
| Machine height | 400 mm |
| Net weight | 7 kg |
Technical sources: Original Prusa MK3.9S — documentazione ufficiale · Original Prusa MK3.5S — specifiche tecniche ufficiali · MK4, XL — domande frequenti (FAQ)
Undocumented specifications (35)
- Kinematics: Not documented
- Shared dual-nozzle area X: Not documented
- Shared dual-nozzle area Y: Not documented
- Shared dual-nozzle area Z: Not documented
- Enclosed as standard: Not documented
- Installed toolheads / extruders: Not documented
- Filament diameter: Not documented
- Standard nozzle: Not documented
- Available nozzle diameters: Not documented
- Nozzle material: Not documented
- Build plate: Not documented
- Maximum hotend temperature: Not documented
- Maximum bed temperature: Not documented
- Chamber heating: Not documented
- Maximum chamber temperature: Not documented
- Advertised maximum print speed: Not documented
- Advertised typical print speed: Not documented
- Maximum travel speed: Not documented
- Maximum acceleration: Not documented
- Maximum volumetric flow: Not documented
- Minimum layer thickness: Not documented
- Maximum layer thickness: Not documented
- Multicolor system: Not documented
- Camera: Not documented
- Air filtration: Not documented
- Control display: Not documented
- Listed slicers: Not documented
- Firmware: Not documented
- Internal storage: Not documented
- Manufacturer-listed materials: Not documented
- Rated power: Not documented
- Power supply: Not documented
- Advertised noise: Not documented
- Leveling method: Not documented
- Advertised Z accuracy: Not documented
No published compatibility for this printer.
Related guides
General guides help identify print defects. Follow the manual for your exact model and variant for disassembly, maintenance and calibration.
- First layer not sticking: causes and checks
How to recognise a first layer that is too high, too squished or uneven and fix it in order: plate cleaning, slicer profile, leveling, Z offset. Based on official guidance from Bambu Lab, Prusa, Creality, Elegoo and Anycubic.
- Warping: corners lifting off the bed with ABS, ASA, PETG and PLA
Why corners curl and how to reduce it: plate cleaning, drafts, enclosure, bed temperature, brim and ears, cooling and glue. Based on official guidance from Bambu Lab and Prusa and on user experience.
- Clogged nozzle and under-extrusion: find where the blockage is and fix it
How to tell a blockage in the PTFE tube, the extruder or the hotend apart, when to use the needle and cold pull, how to recognise heat creep, and when replacing the nozzle, PTFE tube or gears is actually justified.
- Wet filament: recognise it, dry it and store it
Symptoms of filament that has absorbed moisture, the most sensitive materials, how to dry following Bambu Lab and Prusa official tables without damaging spool or filament, and how to keep it dry.
- Stringing and oozing: how to get rid of filament strings and blobs
How to recognise stringing and oozing, the main causes (wet filament, temperature, retraction, travel moves, nozzle) and the checks to do in order, with official guidance from Prusa, Bambu Lab, Creality and Elegoo.
- Layer shifting: causes and checks in order
Why layers shift along X or Y and how to find the cause: obstructions, collisions with curled parts, belts, pulleys, speed, electronics cooling and motors, with official guidance from Prusa, Bambu Lab, Creality, Elegoo and Anycubic.
- Ringing and ghosting: getting rid of ripples on FDM print walls
What ringing (or ghosting) is, why it appears after corners and lettering, and how to fix it in order: printer surface, loose parts, belts, lubrication, vibration calibration (input shaping), speed and acceleration.
Official documentation
Manuals and guides published by Prusa Research. Links go to the manufacturer’s site; we consulted them on the date shown.
- Support page
-
- Prusa Research, 7 models — available upgrades for Prusa printers — English, accessed on October 5, 2026
- Support hub page (Knowledge Base) — English, accessed on October 5, 2026
- User manual
-
- MK4S, MK3.9S — user manual (3D Printing Handbook 1.01, PDF) — English, accessed on October 5, 2026
- MK4S / MK3.9S — user manual in Italian (Handbook 1.01, PDF) — Italian, accessed on October 5, 2026
- Assembly
-
- MK3.9, MK3.9S — upgrade guide to MK3.9S — English, accessed on October 5, 2026
- MK3/MK3S/MK3S+ → MK4S/MK3.9S — upgrade assembly guide — English, accessed on October 5, 2026
- Index of assembly manuals — English, accessed on October 5, 2026
- Maintenance
-
- Prusa Research, 4 models — regular maintenance — English, accessed on October 5, 2026
- Prusa Research, 8 models — belt tension adjustment — English, accessed on October 5, 2026
- Printer maintenance category — English, accessed on October 5, 2026
- Troubleshooting
-
- Prusa Research, 4 models — clogged nozzle — English, accessed on October 5, 2026
- Troubleshooting (index) — English, accessed on October 5, 2026
- MK4/S, MK3.9/S — filament won't load — English, accessed on October 5, 2026
- MK4/S, MK3.9/S — blown fuse — English, accessed on October 5, 2026
- Parts replacement
-
- MK4S, MK3.9S — Prusa Nozzle replacement — English, accessed on October 5, 2026
- MK4S, MK3.9S — hotend assembly replacement — English, accessed on October 5, 2026
- MK4S, MK3.9S — print fan replacement — English, accessed on October 5, 2026
- Firmware and software
-
- Prusa Research, 8 models — how to update the firmware — English, accessed on October 5, 2026
- Technical specifications
-
- Original Prusa MK3.5S — official technical specifications — English, accessed on October 5, 2026
- MK3.9 → MK3.9S — upgrade kit, contents and what's new — English, accessed on October 5, 2026
Sources
- Original Prusa MK3.9S — official documentation — Prusa Research, accessed on October 4, 2026
- Original Prusa MK3.5S — official technical specifications — Prusa Research, accessed on October 5, 2026
- MK4, XL — frequently asked questions (FAQ) — Prusa Research, accessed on October 5, 2026