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

The MK4S is now available as a “plug and print” assembled printer (take it out of the box, let it finish the 10-minute Selftest, and start printing) and printer assembly kit. It is also available in a fully assembled bundle with the ready-to-go MMU3 unit sitting on top, so you can start printing with multiple colors right after unpacking.

 

And, of course, there’s an upgrade kit for all current owners – our iconic printer design really gets to shine here: if you already own an MK4, you don’t have to buy a whole new printer. You can simply upgrade it for 99 USD / 109 EUR (VAT incl.) and get ALL the new features of the new model – and they are pretty awesome! I’ll give you a complete rundown in a second, but first, I want to give a short recap of the MK4 just in case it’s the first time you hear about it.

The MK4 quickly became our fastest-selling 3D printer, and so far, it has collected over 4,000,000 testing hours in our print farm, making the MK4 extremely reliable (warranty claim rate is consistently under 1%).

Our printers get continuously better. After the MK4 was launched, we introduced free updates like completely reworked network functionality with instant network printing, G-code streaming and .bgcode compressed file format for faster network transfers and vastly improved Prusa Connect and plenty of quality-of-life improvements in the firmware (like the Cold Pull wizard). And even the MK3 has been receiving updates for over six years now.

We ship around 10,000 3D printers each month directly from our HQ in Prague, Czech Republic, and we also started manufacturing them in the USA. There are over half a million Original Prusa printers in the wild and only around 20 printers per month need to be sent back to us for hands-on maintenance. Don’t believe it? Check out our Trustpilot score or Google Reviews! 😉

So, now, onto the new stuff!

Give me the tl;dr version!

Compared to last year’s model, the MK4S features completely reworked cooling that enables much faster printing while retaining the same level of top-quality prints (durability, smooth surfaces) and dimensional accuracy.

But we actually pushed the quality further in several areas. The new high-performance 360° cooling enables the printing of extremely steep overhangs. In areas where other printers would already need a hefty amount of supports, the MK4S can effortlessly print a great-looking overhang. Why does it matter? Because with less supports, you save both time (faster prints) and material (less plastic thrown to waste) and it’s an absolute godsend when you want to print with flexible filaments where removing supports is pretty painful. And you also get even better surface quality, especially on materials like PETG.

Furthermore, the MK4S now comes standard with a high-flow nozzle of our own design based on the CHT technology. In short: high-flow nozzles enable you to print faster with the materials you already have, know, and love. You don’t have to look for new “high-speed” ones. Depending on the material, you’ll get between 45 to 114% increase in flow rate.

Plus, we have tweaked our firmware and print profiles further, so all these things combined make the MK4S faster than the MK4 while delivering even better print quality. And since we’re using the MK4 as the base platform, the MK4S inherits all of its proven reliability and other advantages, such as the open design which enables effortless maintenance and upgrades.

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.

Many of the MK4S parts are now printed from PC Blend Carbon Fiber or injection-molded, and we’re also introducing two new awesome 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 regarding your orders and upgrades, so please find the main summary in the box below:

Shipping info, upgrades, information for existing users

Here’s a short summary of the most important things regarding MK4S, its availability, and info for existing users of the MK series:

  • Everyone who ordered an MK4 (assembled or kit) between August 1st and 12th, will receive a voucher for a free MK4S upgrade – you only need to cover the shipping (the vouchers will be sent by August 16th and you will get a priority processing on your order)
  • MK4S Assembled 3D printer, MK4S Printer Kit and a new bundle featuring the MK4S Assembled with MMU3 assembled are now available in our eshop and we have units in stock
  • MK4S upgrade kits (to upgrade from an older printer) will be available by the end of August
  • All current unshipped orders of the MK4 3D printers and MK3.5/MK3.9 and MK4 upgrades will be automatically converted to the “S” upgrades
  • Owner discounts that apply to MK4 printers are automatically converted to the MK4S version as well

These are some really substantial additions, definitely not just a small reliability upgrade. If you want to know more about them, keep on reading. Let’s get technical! 😉

Redesigned 360° Cooling

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. Do you remember when we said that the innovations from the Prusa Pro line would trickle down to our desktop printers? We were not kidding. 🙂 We truly learned a lot while we were designing the industrial Prusa Pro HT90 and now we can fully utilize our knowledge in the MK4S.

The new printer features a new 360° cooling solution developed from scratch. It utilizes a high-pressure turbine with a redesigned fan shroud offering powerful cooling with carefully optimized airflow.

We considered and tested many other solutions, like a blanket fan on the side. However, a blanket fan doesn’t offer complete coverage from all sides (the object itself can block the airflow). With a powerful extruder-mounted fan, though, we can direct the cooling precisely where we need to.

The new fan may look bulkier than the old one, but the weight of the Nextruder remains virtually unchanged. The fan model and its position have been carefully picked after months of research including virtual airflow simulations. Its position is precisely calculated so that it doesn’t cool down the nozzle or blow the hot air back toward the heatsink. 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.

The new cooling design enables effortless printing of extremely steep overhangs (depending on the model geometry, you can effortlessly print up to a 75-degree angle) so you can print even very complex models without supports, saving both time and material. And one more thing is further 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 might have encountered a small issue: when the nozzle stayed in one place for too long, it had a tendency to melt some of the already deposited material. With a more powerful cooling system, the quality of such parts is much better.

New high-flow nozzle

The MK4S features a new custom-made high-flow nozzle based on the CHT technology. Depending on the material, you gain an increase in the volumetric flow rate between 45 to 114 percent.

As I already mentioned, 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. 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.

With the new high-flow nozzle, you can get more out of the same filaments you already know and love – you don’t have to switch to any specialized filaments just for the sake of higher speed. Check out the table below – it gives you a good overview of the differences between various nozzle models. Everything is measured with standard materials, you don’t have to look for the fine print saying “measured with high-flow filament.” 😉

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

Let’s talk about speed!

The combination of tweaked firmware, print profiles, and the new high-flow nozzle allows the MK4S to print faster than its predecessors and it’s on par with the fastest printers on the market thanks to the native implementation of Input Shaper and Pressure Advance technologies.

We’re not huge fans of the Speed Boat Race benchmark, but you would ask anyway. 🙂 The Benchy according to the rules can be finished in a mere 14 minutes (and it looks awesome). And our specially tuned “bonkers” Benchy can be done in an awesome 8 minutes.

However, just to make it clear: speed is nothing without quality, so if you eventually have to reprint something either because the print failed or the durability is not what you expected, then a printer that’s faster on paper isn’t faster in the real world. With our printers, we always aim for maximum print quality, even when it means sacrificing a little bit of print time. Waiting a few more minutes 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 clean UI, focused on functionality

With the release of the MK4S, we’re also launching our new (and fully optional) native Android and iOS app. And don’t worry: it’s not just for the MK4S – any Prusa Connect-compatible printer works as well. And yeah, I know what you’re thinking: everybody has an app now. That’s true, of course. But sometimes it goes to an extreme and many devices can’t even be properly configured without an app! And what do you do when the app is not compatible with your phone? It annoys me to no end and I guess 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 receive push notifications. All in all, it’s a good set of useful features for remote management of your prints. But there’s also one more thing that I think will become very useful for many of you: You can access Printables directly from the app and if a project contains a printable file, you can simply tap the print button and start printing it right away without the need to use a slicer.

The app also allows you to easily set up Wi-Fi with a simple NFC tap against the electronics cover.

And just like with everything we do, from PrusaSlicer to Prusa Connect, we’ll keep adding useful new features over time.

We’re planning to add the following things in the near future:

  • Camera support
  • Advanced notification settings
  • Improved management of direct printing from 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 all its predecessors.

100% Security and Open Source

Security always comes first. You can run your printer in an offline or local mode, and we will never secretly collect information about your print files or your printer’s surroundings unless you specifically agree to share it with us (e.g., for tech support purposes).

Our printers can be operated in fully offline mode, the Wi-fi module is detachable, and the firmware files and PrusaSlicer are open-source, so you can always inspect the code and do an independent audit. Also, we published a page with a clean overview of our open-source efforts. You can easily update the printer’s firmware via a USB drive, and there’s one more thing that might be often overlooked: we even enable offline updating of PrusaSlicer profiles, so you don’t need internet access to utilize PrusaSlicer in its full!

Plus, as an EU-based company, we’re fully committed to comply with the very strict GDPR law.

Accessories for Makers

With open-source firmware, printable plastic parts, and more, our printers are very open to any sort of user mods, tweaks, and hacks. And we want to take it one step further. This is why we’re now introducing an optional accessory: a GPIO “hackerboard” for advanced users. This small electronics board connects directly to the mainboard and you can control it using G-code commands. 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 GPIO hackerboard is currently available as a pre-order and we will start shipping it in just a few weeks – we’re in the process of finishing the documentation, so you can come up with some cool projects in the meantime. 🙂

The other accessory is an optional accelerometer for printer modders. Our printers are pre-configured with optimized Input Shaper values from the factory. However, if you decide to make significant changes to your printer (e.g., by installing a mod on the Nextruder), you might need to recalibrate these values. For such opportunities, we’re launching an optional accelerometer accessory, so you can calibrate your printer. Needless to say: the difference is negligible on a stock MK4S. The accelerometer is now available in our shop.

Print Quality Improvements

Every manufacturer claims that their printer delivers the highest quality prints – but what does that actually mean? When we say we aim for the highest print quality, we talk about the following areas:

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

Most of them are pretty self-explanatory, so I would like to focus on two of them because this is where we made some substantial improvements. I already discussed vastly better overhang printing, so let’s take a look at dimensional accuracy and print durability.

Dimensional Accuracy

As for dimensions accuracy, I feel like this is something that’s not discussed enough. Or at least not online, because at various events and shows, people often tell us that even though they print fast prototypes on other printers, when they want precision and repeatability, they always end up with our machines.

When you design a part that should fit together with an existing object or you want to make sure that the holes for screws will be a perfect match, you want to have a dimensionally-accurate 3D print. Our firmware and print profiles are tweaked for maximum print quality and we have proof. 🙂 We measured printed models from various machines against the original 3D model. And we used various techniques to compare them. Below, you can see a measurement made with 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 is a print from a competing printer. The more the color deviates from green (either towards red or blue/purple), the more inaccurate the print is. The measurement was done by the Institute of Machining Technology, Design and Metrology, Faculty of Mechanical Engineering, CTU in Prague. The fixtures were compared with the STL model using the Carl Zeiss Metrotom 1500 computed tomograph.

Another test was done on a highly-accurate multisensor measurement system, the Keyence LM-X-100TL showing how well the dimensions match.

We went for this option because the standard all-printed tolerance tests don’t really reflect reality. When the entire model is 3D printed, the tolerances may in fact allow movement within a controlled tolerance test. If you need to fit other components (screws, nuts) with exact dimensions, the reality may be very different.

We hear from many of our users at various shows and events that they are switching back to our printers after experimenting with other machines, exactly because of the precision we are achieving.

Sturdy, durable prints

The combination of the 360° cooling system and the new high-flow nozzle enables the MK4S to deliver very durable, sturdy prints. It’s not just about total cooling power, though, but about the most effective delivery. Extremely strong fans tend to create an overcooling effect, causing the layers to adhere poorly. Most of the time, the MK4S print fan doesn’t run anywhere close to its maximum speed, but it’s the air distribution that creates a massive difference (again, this is why we’re not using a blanket fan).

The high-flow nozzle ensures the filament is properly melted for the best adhesion. We also adjusted the print profiles. The SPEED profiles are now optimized for faster prototyping, however, we kept the STRUCTURAL profiles at the same speed on purpose – to increase the print durability even more. So, yes, our profiles might be a bit conservative when it comes to speed, but you can be sure that any sort of bracket or holder you design for your workshop won’t fall apart after a while.

Available as fully assembled and kit

The MK4S is available as a fully assembled “plug and print” version, where you simply take the printer out of the box, put the filament on a spoolholder and finish the automated Selftest. This all takes less than 15 minutes – and you’re ready to print. We have handbooks, academy courses, tutorials, guides, tips, tricks and more to get you started with 3D printing in the shortest amount of time possible. Plus, there’s an awesome community and our renowned 24/7 tech support available via live chat, just in case you need a hand.

Plus, the design of our printers allows us to offer the assembly kit – one of the best STEM projects out there. You can assemble the entire printer yourself, or with your kids, grandparents… anyone! You need just a set of screwdrivers and a bit of time and you can build your very own MK4S, learning everything about 3D printers and how they work in the process. It’s a ton of fun and the assembly kit is still one of our most popular offers.

Greenguard certification for the MK4

Before I wrap up, I’d like to mention something that resonated quite a bit in the online circles: safety when it comes to “fumes” from open-frame printers. Short version: the Original Prusa MK4 with Prusament PLA and Prusament PETG passed the UL 2904 testing and received a renowned Greenguard certification as the first and only desktop 3D printer on the market. And the MK4S is set to follow shortly.

To explain: the “fumes” are basically two things – particle and chemical emissions. And their nature is affected by the filament composition and the printer itself. In other words: even if you label a material as PLA, it can contain very different components compared to PLA from another brand. This is why we tested a specific combination of a 3D printer and material.

When it comes to the printer, it is mostly the temperature and time used to heat the filament. Overheating the material for an increased flow rate may lead to a less safe printing environment. The CHT nozzles seem to perform better – increased flow rate without overheating. Either way, the only option to be absolutely sure is to perform testing. That’s exactly what we did and we passed the Standard Method for Testing and Assembling Particle and Chemical Emissions from 3D printers with flying colors. You can always verify that on the UL website here.

Shipping now!

With the MK4S, we’re expanding on our proven iconic printer design. We’ve added plenty of improvements during the past 14 months. It’s easier than ever to set up everything around the printer with the touch screen – including wireless setup. Now, you can let the printer scan for Wi-Fi networks and enter the password via an on-screen keyboard. There’s a new Cold Pull wizard directly in the printer. Stuck filament detection, user interface configuration, Prusa Connect integration… too many to name them all!

Plus you can rely on the features that brought our printers a ton of praise: our outstanding 24/7 tech support in 7 languages, incredible reliability, easy maintenance, no glued parts, upgradability, regular firmware updates, long-term support, third-party support (filaments, mods), plenty of accessories and much much more.

Speaking of accessories: for advanced materials, we have the Original Prusa Enclosure and when you want to print with up to five colors at the same time, we have the MMU3 – the fastest and most efficient single-nozzle multi-material solution producing minimal waste. You don’t even need to assemble it anymore, as you can get it ready for printing along with the assembled MK4S.

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

Happy printing!