The Original Prusa MK4S is here! Powerful 360° cooling, high-flow nozzle, Prusa App, Hackerboard and more!

It is the middle of the hot summer here in Prague and we have a cool new 3D printer for you (pardon the pun, but there is a reason for it)! The new Original Prusa MK4S brings a completely redesigned 360° cooling with a high-performance turbine, higher print speed, even better print quality, a new Prusa app for remote print management, lots of usability improvements based on your feedback, and two new awesome gadgets for makers and modders. And more!

The MK4S is now available as “Plug and Print” assembled printer (take it out of the packaging, let it run the 10-minute self-test and start printing) and Printer kit It is also available in a fully assembled package with the ready-to-use MMU3 unit sitting on top so you can start printing with multiple colors right out of the box.

 

And of course there are also an upgrade kit for all previous owners – our iconic printer design comes into its own here: If you already own an MK4, you don't have to buy a whole new printer. You can simply buy it for 99 USD / 109 EUR (incl. VAT) and get ALL the new features on the new model - and they're pretty awesome! I'll give you a full review in a second, but first I want to give you a quick recap of the MK4, just in case this is the first time you've heard of it.

The MK4 quickly became our best-selling 3D printer and has over 4,000,000 test hours collected in our printing farm, which makes the MK4 extremely reliable (the warranty claim rate is consistently below 1%).

Our printers are getting better and better. After the launch of the MK4, we introduced free updates such as a completely redesigned network functionality with instant network printing, G-code streaming and the compressed file format .bgcode for faster network transfers and a greatly improved Prusa Connect as well as numerous firmware improvements (such as the cold pull assistant). And even for the MK3 there are for over six years Updates.

We ship about 10,000 3D printers every month directly from our headquarters in Prague, Czech Republic, and have also started production in the USA. There are over half a million Original Prusa printers in the wild and only about 20 printers per month must be returned to us for practical maintenance. You don't believe it? Check out our Trustpilot Rating or Google reviews! 😉

So, now for the new things!

Short and sweet!

Compared to last year’s model, the MK4S has a Completely redesigned cooling system , which enables significantly faster printing while maintaining consistently high print quality (durability, smooth surfaces) and dimensional accuracy.

But we have improved the quality even further in several areas. The new powerful 360° cooling enables printing of extremely steep overhangs. In areas where other printers would already require a significant amount of supports, the MK4S can effortlessly print a great looking overhang. Why is this important? Because with fewer supports you save both time (faster prints) and material (less plastic in waste). And it's an absolute godsend if you want to print with flexible filaments where removing supports is quite a hassle. Plus you get an even better surface quality, especially with materials like PETG.

In addition, the MK4S now comes standard with a high-flow nozzle that we developed ourselves based on CHT technology. In short: High-flow nozzles allow you to print faster with the materials you already have, know and love. You don't have to look for new "high-speed" filament. Depending on the material, you get a 45 to 114% higher flow rate.

We have also further optimized our firmware and print profiles so that all these things together make the MK4S faster than the MK4 while delivering even better print quality. And since we use the MK4 as the base platform, the MK4S inherits its proven reliability and other advantages, such as the open design, the effortless maintenance and upgrades enabled.

We have a brand new native iOS and Android Prusa app for remote print monitoring and management, which allows you to print projects directly from Printables without using a slicer. The app is already available in the respective app stores and offers another useful feature: you can easily set up the printer's Wi-Fi with an NFC tap.

Many of the MK4S parts are now out PC Blend Carbon Fiber or manufactured by injection molding, and we also introduce two new, fantastic additions for all modders and hackers: an optional GPIO “Hackerboard” and an accelerometer addon for printer modders.

So this is a quick summary of the new additions and innovations. I'm sure you have a lot of questions about your orders and upgrades, so the most important summary is in the box below:

These are some really substantial additions, definitely not just a minor reliability upgrade. If you want to know more about them, read on. Let's get to the tech! 😉

Redesigned 360° cooling

We spent a long time looking for a new fan to replace the current solution. This was quite a challenge because the MK4's cooling 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. Remember when we said that the innovations from the Prusa Pro series would spill over to our desktop printers? We weren't kidding 🙂 We really learned a lot when we tested the industrial Prusa Pro HT90 and now we can fully utilize our knowledge in the MK4S.

The new printer features a completely new 360° cooling solution. It uses a high-pressure turbine with a redesigned fan shroud that provides powerful cooling with carefully optimized airflow.

We have considered and tested many other solutions, such as a side fan. But a side fan does not provide complete coverage from all sides (the object itself can block the airflow). With a powerful fan mounted on the extruder, on the other hand, we can direct the cooling exactly where we need it.

The new fan may look bulkier than the old one, but the weight of the Nextruder remains virtually unchanged. The model of the fan and its position were carefully chosen after months of research, including virtual airflow simulations. Its position is precisely calculated so that it does not cool the nozzle or blow the hot air back to the heatsink. As always we have gone a little beyond what is necessary – the new turbine is powerful enough to run at 60-70% of its maximum speed most of the time (it only goes to 100% in certain situations), so she is still very quiet and at the same time delivers much higher performance compared to the old model.

The new cooling design enables effortless printing of extremely steep overhangs (depending on the model geometry, you can print up to an angle of 75 degrees with ease), allowing you to print even very complex models without supports, saving both time and material. And something else has improved thanks to the new cooling: whenever you printed a tall, thin object (a tower, a spear in the hand of a miniature warrior), you may have encountered a small problem: if the nozzle stayed in one place for too long, it tended to melt some of the material already applied. With a more powerful cooling system, the quality of such parts is much better.

New high-flow nozzle

The MK4S features a new, tailor-made high-flow nozzle based on CHT technology. Depending on the material, you can achieve a Increase in volume flow between 45 and 114 percent.

As I mentioned earlier, a high-flow nozzle essentially allows you to print faster because the material in the nozzle is also melted faster (and better), resulting in improved volumetric flow. If you want to print fast, it's not just about moving the extruder faster, you also need to get the filament to its optimal melting point, otherwise the print will finish quickly, but the adhesion between layers will be extremely poor.

With the new high-flow nozzle you can get more out of the same filaments you already know and love – You don’t need to switch to special filaments just to get higher speed. Check out the table below – it gives you a good overview of the differences between the different nozzle models. Everything is measured with standard materials, you don’t need to pay attention to the small print that says “measured with high-flow filament” 😉

Comparison of volume flow – 0.4 mm and 0.6 mm nozzle
	Standard nozzle [mm3]	MK4S High-Flow Nozzle [mm3]	increase

Replacing the nozzles is still extremely easy - simply loosen two thumbscrews (no tools required) and separate the entire hotend assembly, or simply use a 3D printed nozzle adapter and swap only the nozzle (it takes about 30 seconds). We also offer an adapter that makes the Nextruder compatible with any type of V6 nozzle.

Let's talk about speed!

The combination of optimized firmware, print profiles and the new high-flow nozzle allows the MK4S to print faster than its predecessors. Thanks to the native implementation of the Input Shaper and Pressure Advance technologies It is one of the fastest printers on the market .

We are not big fans of the Speed ​​Boat Race benchmark, but you would ask anyway 🙂 The Benchy can be completed according to the rules in just 14 minutes (and it looks fantastic). And our specially tuned “bonkers” Benchy does it in just 8 minutes .

But just to be clear: Speed ​​is nothing without quality, so if you ever need to reprint something because the print failed or the durability didn't meet your expectations, then a printer that is faster on paper is not faster in reality. With our printers, we always strive for maximum print quality, even if that means sacrificing a little printing time. A few extra minutes of waiting for a better looking print is worth it. And if you're in a hurry, we have two new rapid prototyping profiles for maximum speed.

Prusa App – Simple and clear user interface, focus on functionality

With the release of the MK4S we also introduce our new (and completely optional) native Android and iOS app And don't worry: it's not just for the MK4S - any Prusa Connect compatible printer will work too. And yes, I know what you're thinking: everyone has an app now. That's true, of course. But sometimes it goes to the extreme and many devices can't even be configured properly without an app! And what do you do if the app isn't compatible with your phone? This annoys me to no end and I think it goes without saying that this is not what we're aiming for.

The Prusa app has a nice, clean and simple design. You can get a quick overview of all your printers, see all running tasks and start, pause and stop prints from anywhere. And you can also get push notifications. All in all, a good package of useful features for remotely managing your prints. But there is one more feature that I think will be very useful for many of you: you can access Printables directly from the app and if a project contains a printable file, you can just tap the Print button and start printing immediately, without having to use a slicer.

With the app you can also Easily set up Wi-Fi by tapping the NFC tap on the electronics cover.

And as with everything we do at PrusaConnect do, we will continue to add useful new features over time.
We plan to add the following things in the near future:

• Camera support
• Advanced notification settings
• Improved management of direct printing of printables
• Widgets
• …and more

However, rest assured that the app will remain optional , so if you prefer simplicity over smart features, the MK4S works just as well in offline mode as any of its predecessors.

Accessories for Makers

With open source firmware, printable plastic parts and more, our printers are very open to any kind of user modifications, optimizations and hacks. And we want to go one step further. That is why we are now introducing an optional accessory: a GPIO “Hackerboard” for advanced users. This small electronic board connects directly to the main board and you can control it with G-code commands. For example, you can solder on an LED strip and have it flash certain colors when a print is finished. You can also set up a remote camera trigger, turn on filtering, or design your own print harvester. The possibilities are practically endless and we can't wait to see what crazy ideas you come up with!

The GPIO Hackerboard is currently as Pre-order available and we will ship it in a few weeks – we are currently finishing up the documentation so you can come up with some cool projects in the meantime 🙂

The other accessory is a optional accelerometer for printer modders . Our printers are pre-configured from the factory with optimized Input Shaper values. However, if you decide to make significant changes to your printer (e.g. by installing a mod on the Nextruder), you may need to recalibrate these values. For such occasions, we are launching an optional accelerometer accessory that will allow you to calibrate your printer. Of course, the difference is negligible on a stock MK4S. The accelerometer is now available in our shop .

Improved print quality

Every manufacturer claims that their printer delivers the highest quality prints - but what does that actually mean? When we say we strive for the highest quality prints, we mean the following areas:

• Dimensional accuracy
• Unmatched overhang quality
• Solid, durable prints at high speed
• Beautifully smooth surfaces
• Colour fastness

Most of these points are pretty self-explanatory, so I want to focus on two of them, because this is where we made some significant improvements. I've already talked about the much improved printing of overhangs, so let's take a look at the dimensional accuracy and durability of the print.

Dimensional accuracy

Regarding dimensional accuracy, I feel like it is not talked about enough. At least not online, because at various events and trade shows, people often tell us that while they print quick prototypes on other printers, but when they want precision and repeatability, they always end up with our machines.

If you are designing a part that will fit an existing object, or if you want to make sure that the holes for screws fit perfectly, you will want a precise 3D printing Our firmware and print profiles are optimized for maximum print quality and we have the proof 🙂 We compared printed models from different machines with the original 3D model. And we used different techniques to compare them. Below you can see a measurement made with the Zeiss Metrotom 1500, a state-of-the-art industrial CT scanner.

On the left you can see a standard MK4S 3D print, on the right a print from a competing printer. The more the color deviates from green (either towards red or blue/violet), the less accurate the print is . The measurement was performed by the Institute of Machining Technology, Design and Metrology, Faculty of Mechanical Engineering, CTU in Prague. The devices were compared with the STL model using the Carl Zeiss Metrotom 1500 computer tomograph.

A further test was carried out using a high-precision multi-sensor measuring system, the Keyence LM-X-100TL, to see how well the dimensions match.

We chose this option because standard tolerance tests for the entire print do not truly reflect reality. When the entire model is 3D printed, tolerances can indeed allow movement within a controlled tolerance test. If you need to incorporate other components (screws, nuts) with exact dimensions, reality can be quite different.

We hear from many of our users at various trade shows and events that they return to our printers after experimenting with other devices precisely because of the precision we achieve.

Stable, long-lasting prints

The combination of the 360° cooling system and the new high-flow nozzle enables the MK4S, to deliver very durable, robust prints . It's not just about the overall performance of the cooling though, it's also about the most effective delivery. Extremely powerful fans tend to create an overcooling effect, making layers stick poorly. Most of the time the MK4S print fan isn't running anywhere near its top speed, but it's the air distribution that makes a huge difference (again, this is why we don't use a blanket fan).

The high-flow nozzle ensures that the filament is melted properly so that it adheres optimally. We've also adjusted the print profiles. The SPEED profiles are now optimized for faster prototyping, but we've intentionally kept the STRUCTURAL profiles at the same speed - to increase print durability even further. Yes, our profiles may be a little conservative when it comes to speed, but you can be sure that any type of mount you design for your workshop won't fall apart after a while.

Available as a kit and fully assembled

The MK4S is fully assembled “Plug and Print” version available, where you simply take the printer out of the box, place the filament on a spool holder and complete the automatic self-test. All this takes less than 15 minutes – and you are ready to print. We have Manuals, tutorials, guides, tips, tricks and much more to get you started with 3D printing in no time. Plus, there is a great community and our reputable 24/7 tech support available via live chat in case you need assistance.

The design of our printers also allows us to Kit - one of the best STEM projects out there. You can build the entire printer yourself, or with your kids, grandparents... anyone! All you need is a set of screwdrivers and some time, and you can build your own MK4S while learning all about 3D printers and how they work. This is great fun and the kit is still one of our most popular offerings.

Greenguard certification for the MK4

Before I conclude, I want to mention something that has been getting a lot of buzz in online circles: safety when it comes to "fumes" from open frame printers. The short version: The Original Prusa MK4 with Prusament PLA and Prusament PETG has passed UL 2904 testing and received a prestigious Greenguard certification as the first and only desktop 3D printer on the market. And the MK4S will follow shortly.

PSA2🚨 Today is a great day to talk about 3D printing safety 🤓 Another elephant in the room is “fumes” from open-frame printers. TLDR: It can be safe and I have the receipts ⤵️

The “fumes” are basically two things – particles and chemical emissions. They are affected by two… pic.twitter.com/udulYQyh1S

— Josef Prusa (@josefprusa) August 4, 2024

To explain, the "fumes" are basically two things - particles and chemical emissions. And their nature depends on the composition of the filament and the printer itself. In other words, even if you call a material PLA, it may contain very different ingredients than another brand's PLA. That's why we tested a specific combination of 3D printer and material.

With the printer, it's all about the temperature and the time used to heat the filament. Overheating the material for increased flow rate can lead to a less safe printing environment. The CHT nozzles seem to work better - increased flow rate without overheating. Either way, the only way to be completely sure is to do testing. That's exactly what we did, and we passed the standard method of testing and compiling particle and chemical emissions from 3D printers with flying colors. You can always check that out on the UL website check.

Now available!

With the MK4S we continue to build on our proven, iconic printer design. Over the last 14 months we have made a variety of improvements. It's easier than ever to set up everything about the printer via the touchscreen - including wireless setup. Now you can have the printer search for Wi-Fi networks and enter the password via an on-screen keyboard. There's a new cold pull wizard right in the printer. Stuck filament detection, UI configuration, Prusa Connect integration... too many to name!

Plus, you can count on the features that have earned our printers so much praise: our excellent 24/7 technical support in 7 languages, incredible reliability, easy maintenance, no stuck parts, upgradeability, regular firmware updates, long-term support, third-party support (filaments, mods), tons of accessories and much more.

Speaking of accessories: for advanced materials we have the Original Prusa Enclosure and if you want to print with up to five colours simultaneously, we have the MMU3 - the fastest and most efficient single nozzle multi-material solution with minimal waste. You don't even need to assemble it anymore because you can get it ready to print along with the assembled MK4S.

The MK4S is now available as fully assembled printer (even in a bundle with a fully assembled MMU3) and as Printer kit The upgrade kits (such as the MK4->MK4S ) will follow in the coming weeks.

Have fun printing!