Prusa Core One: Complete Guide to the MK4S Successor

This week’s Monday topic focused on flexible materials on modern hardware, and the Prusa Core One is exactly the kind of machine that finally handles this material category sensibly thanks to its actively controlled chamber. After years in which the MK4 and later the MK4S defined the Prusa portfolio as reliable bedslinger printers with the Nextruder, the Core One arrives as an answer to a question the community had been asking since 2022, when the Bambu Lab X1C defined the category of enclosed CoreXY machines. This guide sums up what the Core One offers, where it differs from the MK4S, what weaknesses it has in its current form, and who should consider switching. It covers the specs, the upgrade path from MK4S, a comparison with the X1C, and the practical implications for filament choice and print settings.

What the Prusa Core One is and why it exists

The Prusa Core One is a fully enclosed CoreXY 3D printer from Prusa Research, built on a steel frame and designed for higher print speeds than the previous bedslinger architecture of the MK series. The print head’s motion in the XY plane is driven by two motors with coordinated belt loops, while the print bed moves only along the vertical Z axis. This configuration eliminates the inertial forces of the large heated bed, which on the MK4S oscillates back and forth, and thus allows significantly higher speeds while maintaining print quality.

The reason the Core One exists was a gap in the Prusa lineup. Since the Bambu Lab X1C launched in 2022, the lineup had been missing direct competition in the enclosed CoreXY segment. The MK4S got incremental improvements but architecturally remained tied to an open frame with a moving bed. The Core One fills that gap and at the same time opens the Prusa platform to materials that require a stable heated chamber, namely ASA, ABS, polycarbonate, and composites with a higher reinforcement content.

The machine is available in two versions: as a kit for self-assembly and as a fully assembled printer. The Ultimate Edition configuration includes additional accessories. For existing MK4S owners, there is an official upgrade path that transforms the existing electronics and Nextruder into the new frame.

Key technical specifications

The Core One’s build volume measures 250 x 220 x 270 mm, a slightly asymmetric format compared with the purely cubic 256 x 256 x 256 mm of the X1C. The 270 mm vertical dimension, on the other hand, gives the Core One an edge for taller parts. The maximum nozzle temperature is 290 degrees Celsius, which covers standard engineering materials including PC and PA with short-fibre reinforcement. For pure PEEK or PEI this is not enough, but that is not the target segment.

The key novelty compared with the MK4S is the actively controlled chamber temperature. The enclosed cabinet with sealed doors maintains a stable environment that suppresses warping in materials with higher shrinkage. Filtration is handled by an add-on Advanced Filtration module that addresses styrene emissions when printing ABS and its derivatives. Without the filter, PLA and PETG can be printed without major limitations in a normally ventilated room.

The Nextruder print head is carried over from the MK4S and retains its direct drive with a reduction gear. That means a high torque ratio on the filament and reliable feeding of flexible materials, an area where Bowden systems have historically struggled.

• Build volume: 250 x 220 x 270 mm
• Maximum nozzle temperature: 290 degrees Celsius
• Construction: CoreXY with a steel frame
• Chamber: enclosed with active temperature control
• Print head: Nextruder with direct drive
• Entry price (kit): from roughly 925 USD

How it differs from the MK4S

The most visible difference is the kinematics itself. The MK4S uses what is called a bedslinger configuration, where the bed moves on the Y axis and the print head on the X axis. This approach is mechanically simpler and cheaper, but it limits print speed because of the inertia of the heated bed. The Core One with CoreXY drive breaks through that barrier and can print significantly faster at comparable quality.

The second fundamental difference is the enclosed chamber. The MK4S is in principle an open printer, although an optional Enclosure box exists. The Core One has enclosure built in from the ground up, including glass doors, sealing, and the option of active chamber heating. Practice shows that a stable chamber temperature between 40 and 55 degrees Celsius has a major impact on the success rate of printing ASA and ABS without cracking between layers.

The third difference lies in the target user. The MK4S stays in the lineup as the entry-level machine with the best price-to-reliability ratio for printing PLA, PETG, and flexible materials. The Core One targets users who need engineering materials and higher speed. In terms of the Nextruder, the PEI sheet, and the software ecosystem, the machines are fully compatible, so filament profiles and workflow remain familiar.

Upgrade path from MK4S

Prusa Research offers an official upgrade kit that allows you to convert an MK4S into a Core One while reusing part of the original electronics, the Nextruder, and the bed. This route is attractive for users who already have an MK4S running and want to gain a CoreXY architecture without the full investment in a new machine. The procedure is documented in the official guides at help.prusa3d.com, where you will find chapters covering the disassembly of the MK4S and the assembly of the Core One+ from the salvaged components.

In terms of difficulty, the upgrade is rated as moderate. The kit assembly has ten chapters covering basic assembly, the rear section, the heated bed, the CoreXY mechanics, Nextruder installation, panelling and electronics, the final trim with doors and xLCD display, and finally calibration. A realistic time estimate for an experienced user is a weekend, for a beginner rather longer.

Before starting the upgrade, it is worth considering whether it makes more sense to buy the Core One+ as a standalone printer and either keep the MK4S as a secondary machine for PLA prints or sell it on the secondary market. Two machines running in parallel dramatically increase a workshop’s throughput.

Comparison with the Bambu Lab X1C

The Bambu Lab X1C is a direct competitor of the Core One and defines the standard against which the Prusa is measured. Both machines share the same basic philosophy: an enclosed CoreXY frame, high speed, automatic calibration, and support for a wide range of materials. They differ, however, in the details that may decide your choice.

The X1C has a symmetric build volume of 256 x 256 x 256 mm and a maximum nozzle temperature of 300 degrees Celsius, so slightly more in both parameters. The Core One, by contrast, offers 270 mm on the Z axis and bets on the Prusa ecosystem with open firmware, local European manufacturing, and a broad community base. The choice between them is often more about ecosystem philosophy than about purely technical parameters.

For printing with multiple materials at once, Bambu Lab offers the AMS as a mature solution with automatic filament swapping. Prusa offers add-on systems for the Core One, but overall integration is still younger. Reviews point out that the Core One has, at this stage, a few teething troubles that firmware updates are gradually addressing, much as the Prusa XL went through in its first year on the market.

• Build volume: Core One 250 x 220 x 270 mm vs X1C 256 x 256 x 256 mm
• Nozzle temperature: Core One 290 degrees Celsius vs X1C 300 degrees Celsius
• Ecosystem: Prusa with open firmware vs Bambu Lab with a more closed platform
• Multi-material system: X1C with the more mature AMS, Prusa with a younger solution
• Manufacturing: Prusa EU, Bambu Lab China

Materials and practical implications for printing

The enclosed chamber opens the Core One up to the whole range of materials that on the MK4S were only feasible with an improvised enclosure or while accepting a higher failure rate. ASA and ABS print reliably in the Core One even on larger parts, where cracking between layers or bed detachment used to happen. Polycarbonate, at reduced speed and a higher chamber temperature, is also a realistic option.

Composite materials with carbon or glass fibres require a hardened nozzle, which you need to buy separately. A standard brass nozzle wears down within a few hours of printing PETG-CF or PA-CF. With a hardened 0.4 or 0.6 mm nozzle, the Core One is ready for functional prototypes with higher stiffness.

For flexible materials such as TPU and TPE, the Nextruder’s direct drive handles common shore hardnesses from 85A to 95A without trouble. Softer variants around 70A require lower speed and care with retractions, but they are printable. This week’s topic focuses precisely on flexible materials on modern hardware, and the Core One fits into that category as a machine that handles flexibles without compromising on speed.

Software, firmware, and the ecosystem

The Core One uses PrusaSlicer as the reference slicer with ready-made profiles for all available materials from the Prusament portfolio as well as for the main third parties. The profiles take into account the specifics of CoreXY kinematics, input shaping, and chamber temperature. For users switching from the MK4S, the workflow is almost identical, just with new default values for speed.

The firmware is based on an open-source foundation and updates over USB or over a network connection. The community reports that the update frequency in the first months after launch was high, which matches a strategy of rapidly tuning detected issues. Users who prefer a stable device without the need for frequent firmware maintenance might want to wait a few months for the device to settle.

Within the ecosystem, the Core One fits into the Prusa Connect platform for remote management, the Printables model library, and the open G-code format. For users who want to experiment with alternative slicers like OrcaSlicer, the Core One is fully open, even though official support and optimisation sit on the PrusaSlicer side.

Pros and cons of the Core One

No machine is perfect, and the Core One has clearly defined strengths and weaknesses that should feed into the decision. Reviews and community reports from the first months on the market paint a fairly consistent picture of what you can expect.

• Pro: an enclosed chamber with active temperature control enables stable printing of ASA, ABS, PC, and composites
• Pro: CoreXY kinematics significantly increase print speed compared with the MK4S
• Pro: compatibility with the Nextruder and the Prusa ecosystem, no learning curve for existing users
• Pro: EU manufacturing with readily available spare parts and a strong community
• Con: in the first months on the market there are minor issues that firmware is gradually resolving
• Con: the asymmetric 250 x 220 mm build area limits some shapes on the Y axis
• Con: the multi-material system is less mature than the Bambu Lab AMS
• Con: styrene emissions filtration is a separate add-on rather than part of the standard package

The Prusa Core One closes a multi-year gap in the Prusa Research portfolio and brings an enclosed CoreXY architecture into the familiar Nextruder ecosystem. For MK4S users hitting the limits of bedslinger architecture when printing ASA, ABS, or composites, the Core One is the logical next step, whether through the official upgrade kit or as a second machine in the workshop. When choosing between the Core One and the Bambu Lab X1C, ecosystem preference matters more than raw technical parameters. A practical tip for prospective buyers: if you do not primarily print engineering materials and PLA with PETG is enough, the MK4S remains the more attractive choice on price.

You can get the Prusa Core One at Prusa’s official store (affiliate link).