Czech AM company Prusa Research has released its latest 3D printer for the desktop market: the Original Prusa MK4S. The new system introduces features like 360° cooling, a high-flow nozzle, a new Prusa app for remote monitoring and firmware updates for faster printing speeds. The system, now available, is being sold as either a fully assembled plug-and-play system ($1099) or as an assembly kit ($799). For existing owners of Prusa’s fastest selling 3D printer, the MK4, an upgrade kit for $99 will be available by the end of the month. Without further ado, let’s jump into all the updates and improvements that the Original Prusa MK4S 3D printer offers.
360° cooling
One of the key improvements to the Original Prusa MK4S is a completely redesigned cooling system. Specifically, the machine integrates a fan with high-performance 360° cooling that unlocks faster printing without sacrificing quality. The upgraded cooling system also enables the extrusion of steep overhangs (up to a 75° angle) without any supports. As Josef Průša, founder of Prusa Research, said: “We spent a long time looking for a new fan that would replace the current solution. This was quite challenging, as the cooling on the MK4 was already very good, and there was a long list of requirements to meet (weight, pressure, noise, PWM, and more) if we wanted a brand-new print fan.” Ultimately, a solution was developed from scratch, leveraging a high-pressure turbine and redesigned fan shroud mounted on the extruder.
“Its position is precisely calculated so that it doesn’t cool down the nozzle or blow the hot air back toward the heatsink,” Průša added. “As always, we went a little further than what was needed – the new turbine is powerful enough to run at 60-70% of its max speed most of the time (it goes to 100% only in specific situations), so it’s still very quiet while delivering much higher performance compared to the old model.”
High-flow nozzle
The MK4S also integrates a high-flow nozzle designed by Prusa Research and based on CHT technology. This high-flow nozzle, which comes standard on the new 3D printer, can be used with all standard filaments and can achieve volumetric flow rate increases between 45 to 114%. “A high-flow nozzle essentially enables you to print faster because the material inside the nozzle is also melted faster (and better) which leads to improved volumetric flow,” Průša explained. “If you want to print fast, it’s not just about moving the extruder faster, but you also need to get the filament to its optimal melting point, otherwise, the print will be finished fast, but the interlayer adhesion will be extremely poor.”
This is possible thanks to the high-flow nozzle, as can be seen in the data supplied by Prusa Research comparing the volumetric flow of a standard 0.4 mm nozzle and the Original Prusa MK4S high-flow nozzle with same diameter:
| Material | Standard nozzle flow rate (mm3) | MK4S high-flow nozzle flow rate (mm3) | Flow-rate increase |
| PLA | 16 | 24 | 50% |
| PETG | 18 | 26 | 44.44% |
| ASA | 17 | 26 | 52.94% |
| PC | 14 | 24 | 71.43% |
The high-flow nozzle in combination with firmware updates result in a 3D printer that is significantly faster than its predecessor, while also achieving superior print quality. According to Prusa Research, the updates make the new system on par with the fastest extrusion 3D printers on the market.
Prusa app
Alongside the new hardware, Prusa Research has also developed and released a new app for iOS and Android which facilitates remote print management and print monitoring. The app, which can be set up using the 3D printer’s Wifi and an NFC tap, enables users to manage multiple 3D printers at once, visualize active tasks, and start, pause or stop prints from remote locations. The Prusa app also gives users direct access to Printables, and allows for one-touch printing without the need for slicing.
We have a brand new native iOS and Android Prusa app for print monitoring and remote print management allowing you to print projects directly from Printables without using a slicer. The app is already available in respective app stores and it also brings another useful feature – you can simply set up the printer’s Wi-fi with an NFC tap. The app is optional and is compatible with the MK4S as well as all other Prusa Connect-compatible 3D printers. According to Průša, we should expect updates and new features for the app, including camera support, advanced notification settings, widgets and more.
Additional features
In true Prusa Research fashion, the new MK4S system is open to user mods and hacks and even comes with optional accessories for advanced users: a GPIO hackerboard and an accelerometer add-on. “This small electronics board connects directly to the mainboard and you can control it using G-code commands,” Průša writes of the GPIO hackerboard. “So, for example, you can solder an LED strip to it and let it flash in specific colors when a print is finished. You can also set up a remote camera trigger, turn on filtration, or design your own print harvester. The possibilities are virtually endless and we can’t wait to see what crazy ideas you’ll come up with!” The accelerometer, for its part, is an optional accessory that enables manual calibration for users that make drastic changes to their MK4S 3D printer.
Ultimately, all the upgrades to the new system translate to a 250 × 210 × 220 mm desktop 3D printer capable of printing at faster rates and with superior quality. To demonstrate the higher quality of the Original Prusa MK4S, Prusa shared a graphic comparing a MK4S print to a competitor’s print. Green indicates where dimensional accuracy is highest, while the yellow and red areas identify where there are inaccuracies.
