Prusa MK4S - FDM 3D printer or kit

An overview

The Prusa MK4S is an open source and open material FFF 3D printer created and designed by Prusa3D, one of the most relevant companies in the 3D printing industry and the manufacturer of one of the most often used 3D printers.  Prusa 3D printers are distinguished by their continuous innovation, always seeking to obtain the highest possible performance, with continuous updates, with prices accessible to any type of user and with rigorous quality control.

Image 1: The Prusa MK4S 3D printer. Source: Prusa3D.

The Prusa MK4S printer is built around the new 32-bit connected architecture (xBuddy Mainboard) and the next-generation extruder (Nextruder). The most outstanding features of the Prusa MK4S printer are its high speed printing capabilities, ease of maintenance, ease of use, silent operation and a wide range of compatible materials (open source) such as PLA, PETG, ABS, ASA, Flex, HIPS, PA, PVA, PC, PP, CPE, PVB, NGEN, composites and more.

Video 1: The main features of the Prusa MK4S printer. Source: Prusa3D.

The Prusa MK4S has a build surface of 250 x 210 x 220 mm, many advanced sensors for extra safety and efficiency, automatic bed leveling, a user-friendly interface and many connectivity options. Over 90 % of the parts have been replaced or improved with respects to the Prusa MK4S predecessor, Prusa MK3. Some of the upgrades include:

• A stiffer frame for better vibration dampening, improved printed parts, and thicker Z-axis rods.
• Auto-leveling with a Loadcell sensor and fully automated first layer calibration.
• An improved extruder with a changed design and quick-swap high-flow nozzle system.
• 360º part cooling system consisting of a high-performance turbine and a redesigned fan shroud.
• Improved connectivity (WiFi, Ethernet, Prusa Connect, NFC, optional Prusa App), an RGB status bar and a new interface screen.

It should be noted that this Prusa MK4S printer is delivered without any extra printing sheet and in the color version black and orange. Apart from the printer (assembled or in a DIY kit version), the basic package includes a handbook, a 1 kg of black Prusament filament, a spoolholder, a USB with sample prints, a toolset, and various maintenance accessories and spare parts. Add-ons such as the MMU3 multi-color printing module or the original Prusa enclosure or extra printing sheets (smooth, textured or satin) must be purchased separately.

The technical specifications of the MK4S printer will be discussed in detail below.

Features in detail

The upgraded extrusion system

At the heart of the MK4S printer is the next-generation extruder Nextruder powered with planetary gears (10:1 gearbox ratio) capable of reaching extrusion temperatures of up to 290 ºC. The heatsink is made of aluminum and the hotend is all-metal.

Image 2: The MK4S extrusion system. Source: Prusa3D.

With the smart Input Shaper and Pressure Advance solutions, the printer can eliminate resonance in prints and predict the flow of the filament. The overall result of those extrusion upgrades is an up to 70 % decrease in print time compared to the MK3 printer. Another convenient solution applied in the Nextruder is the custom breakout board. This means that all fans, heaters, thermistors, etc., are connected directly in the board and swapping any of those elements takes a minute.

Image 3: MK4S's custom-made high-flow nozzle based on CHT technology. Source: Prusa3D.

The MK4S comes equipped with a custom-made high-flow nozzle utilizing CHT technology, designed to increase print speed while enhancing durability. Unlike standard nozzles, this high-flow option allows users to achieve better results without the need for specialized filaments, as it is compatible with common materials. Depending on the filament and nozzle diameter, the new nozzle provides an improved flow rate ranging from 50% to 114% compared to the stock MK4 version. Additionally, an optional Nextruder nozzle adapter is available, enabling compatibility with any V6-type nozzle for broader flexibility.

Chassis, axes and printing bed

The MK4S printer comes with more robust plastic parts, new precise 0.9° stepper motors on the X and Y axes, and Trinamic 2130 stepper drivers. The stepper motors help avoid Vertical Fine Artifacts on prints. Furthermore, the Z-axis rods are now thicker (10 mm), which results in better looking prints, even with problematic filaments such as flexibles.

Image 4: The MK4S improved chassis and axes. Source: Prusa3D.

The MK4S printer is equipped with a magnetic heatbed (up to 120 ºC) with a removable PEI spring steel sheet. The printing bed is automatically calibrated via mesh bed leveling. Thanks to the precise Loadcell sensor, MK4S can produce a perfectly smooth and consistent first layer.

Image 5: The precise Loadcell sensor for automatic bed leveling. Source: Prusa3D.

At the beginning of a print, the printer taps the print surface with the nozzle in a grid-like pattern to measure the distance and then calculates the correct offsets. The result is a perfect first layer on every surface, without manual adjustments.

Safety features

In order to provide a smooth 3D printing experience, and ensure efficiency and successful prints, the Prusa MK4S printer is equipped with multiple sensors responsible for detecting printing failures and alerting the user. The MK4S has an inbuilt filament sensor (Hall sensor) that automatically pauses the printing process when filament runs out. Furthermore, MK4S has a Loadcell sensor for automatic bed levelling, a Power Panic system (full recovery from a complete loss of power), as well as 4 high-precision thermistors (genuine Semitec), fan motors RPM monitoring, hardware overheat detection, overcurrent protection and dual voltage monitoring features.

Connectivity, Prusa Slicer and UI

The MK4S printer is fully supported by Prusa Connect, a software that allows the user to control the printer via Internet connection (WiFi/Ethernet). With Prusa Connect it is possible to drag-and-drop G-Codes into the browser window to upload print files first into the cloud (each user gets 2 GB for free) and then transfer it into the printer’s USB storage and start the print remotely. All communication is encrypted. This feature is especially useful for 3D printer farms.

Image 6: Example of Prusa Connect interface. Source: Prusa3D.

Although MK4S is a 3D printer compatible with most printing programs, such as Cura or Simplify, Prusa3D offers Prusa Slicer, a specific software tailor-made for the Prusa 3D printers. Prusa Slicer has a simple, intuitive and easy-to-use design, while still being a very powerful software that offers a wide variety of customizations, default material settings for over 150 materials and built-in tools (organic supports, slicing, automated object distribution).

Image 7: The Prusa MK4S LCD screen and user interface. Source: Prusa3D.

The Prusa MK4S is controlled via a 3.5" graphic 65k color LCD screen and a straightforward user interface that supports G-code thumbnails, QR codes and other elements that make using the printer as easy as possible. Many of the existing menus have been redesigned and a customizable footer panel has been added. Another new features is an RGB status bar below the LCD screen to signalize the current status of the printer. Next to the LCD, there is a USB-A port for standard USB flash drives.

Available in kit, assembled or assembled with Enclosure

Three possibilities are offered when purchasing the Prusa MK4S: assembled, assembled with Enclosure or in kit.

The first option assumes that the 3D printer is already assembled, calibrated and tested, with complete warranty. Purchasing the already assembled 3D printer saves assembly time, the certainty that it is well calibrated, and the ability to start printing as soon as you receive it. It also includes professional support for any specific questions.

The second option is to acquire the MK4S printer already fully mounted with the official Prusa Enclosure also mounted. Furthermore, the enclosure sent with this printer includes all the extras included with the Prusa Enclosure.  

The third option is to get the Prusa MK4S DIY Kit, which includes all the parts needed to assemble the 3D printer. It's a process that can take a couple of hours or more, especially those who are starting out in the world of 3D printing. However, it turns out to be a very enriching experience, as it helps to know each component, how it is installed, and how the 3D printer works, serving as the basis for solving possible future problems. Prusa3D includes very detailed instructions, with the parts well differentiated from each other and with the cables prepared and cut to measure to facilitate the assembly process. It also contains a manual on 3D printing for those users who are starting out. In addition, it has a large community willing to help any user in distress.

Reliability, performance and affordability

While there are other 3D printers just as inexpensive as the MK4S, they offer a more basic printing experience. In contrast, the Prusa MK4S is a printer with a very affordable price, but with professional capabilities. It is a perfect 3D printer for users who are starting out in the world of 3D printing, for its ease of use and its low cost, and for professionals, due to its great potential and results.

Image 8: Parts 3D printed with Prusa MK4S. Source: Prusa3D.

The Prusa MK4S is excellent as a primary printer, but also as an auxiliary printer (for example, as part of a 3D printer farm). The potential applications for the Prusa MK4S printer include not only domestic but also educational uses, as well as manufacturing for architecture, design, and even prototyping for sectors such as automotive.