Prusa Research is one of the largest companies in the hobbyist 3D printing market. Founded in 2012 by Josef Prusa, the startup has grown to reach every corner of the world. The goal of Prusa is to create reliable machines made of high-quality components while still maintaining an affordable price and an open-source nature.
Although Prusa offers a few different models of machines, the most iconic of their 3D printers is the i3 series, which served as inspiration for many printers in the following years. After the first model was released in 2015, Prusa continued to develop and improve the machines further. Each of the subsequent printers in the i3 series, the MK2 and MK3, were massive hits, and the latest MK4 that was released in March 2023 seems to be no different.
Prusa has committed from its inception to not leave anyone behind. For that reason, the company publishes upgrade kits and guides detailing how to equip older devices with the latest technology. The popular update guide for converting the MK2 into a “MK2.5S+” gave users features of the MK3S+. Now, Prusa sells upgrade kits for the MK3 devices, bringing them closer to the latest MK4.
In this article, we’ll take a closer look at the devices and upgrade kits currently available from Prusa Research. Let’s get started!
MK3S+
Released in 2019, the MK3 was one of the most popular 3D printers on the market. Heir of the MK2, the MK3 offers a lot of handy features that have made this machine a workhorse. A magnetic heated bed, crash detection, and filament sensors are some of the best features to come with the MK3 release.
As Prusa works to continuously improve its machines, soon after the release of the MK3, the company started offering update kits with a SuperPinda probe, an improved filament sensor, and bearing clips for Y-axis bearings. So was born the Prusa i3 MK3S+, which is also available for purchase as a standalone device.
The MK3S+ is one of the most reliable desktop printers on the market. In the All3DP review, we found its construction impressively sophisticated and built to last. True to its open-source nature, the device gets along just as well with third-party materials and software. Its hardware is perfectly capable of printing a wide range of filament materials, although don’t expect some of the fancy features that come stock with newer devices. With the SuperPinda probe, you get automatic bed mesh leveling but not much more. Regardless, it’s a high-quality machine that’ll be able to produce great prints from day one.
Now you can continue to improve your machine with the new upgrade kits created for your MK3/S/+. Let’s check them out:
MK3.5 Upgrade Kit
The MK3.5 kit is the simplest, cheapest, and most essential upgrade kit for your MK3/S/+. Starting at only ~$250, it offers you the 32-bit MK4 motherboard, a color LCD screen, and wireless connectivity. In this way, almost the entire electronics of your machine will be new.
The motherboard is the most important update for the machine, making a big leap forward from the previous 8-bit motherboard. The new xBuddy mainboard can more efficiently process data, giving the printer a speed boost. The improved processing also means that it can take on advanced functionality like input shaping and pressure advance, resulting in noticeably better prints.
The new color LCD screen offers an improved interface that is well-organized, giving you access to print settings, file previews, and more, directly on your device. It also has an LED status bar that is color-coded, turning blue during a print, for example.
Finally, the Wi-Fi and LAN connectivity of the new board allows you to use Prusa Connect for remote print management and device operation, taking your printing workflow to another level.
MK3.9 Upgrade Kit
The MK3.9 upgrade is the mid-range kit and starts at $499. In addition to the 3.5 upgrades, the 3.9 option offers your MK3/S/+ a custom breakout board that expands connectivity and the new Prusa Nextruder extruder, which includes a load sensor cell and a new Hall-effect filament sensor, among other improvements.
The Nextruder was a significant upgrade implemented in MK4 and Prusa XL. Aside from the various built-in sensors that allow for automatic mesh bed leveling, it also aims to improve the accuracy of the filament extrusion using planetary gears. Moreover, the hot end was designed to be easy to replace, and it features an all-metal filament guide that drastically reduces filament leakages. A side effect of making the switch to the Nextruder is an extra 10 mm in the Z-axis build volume!
In addition to functional improvements, Prusa has included improved safety features in this upgrade kit. A power panic sensor detects blackouts and stores enough power to shut down the heat bed and extruder and move the head away from the print in case of an outage. Additionally, an extra thermistor on the heat break helps detect heat creep and prevent thermal runaway.
MK4 Upgrade Kit
The MK4 upgrade kit transforms your MK3/S/+ almost entirely to the MK4. In fact, for $579 it comes with all the 3.5 and 3.9 upgrade kits have to offer, plus 0.9° X and Y stepper motors.
On the MK3 devices, you’ll find 1.8° stepper motors on the horizontal axes. Although there’s nothing wrong with them, 0.9° motors are more precise. This switch aims to eliminate what Prusa Research calls VFA, vertical fine artifacts, which are small surface defects on prints that present as vertical lines. Their presence is inversely related to the quality of the motors: the better the X and Y-axis motors, the less evident the VFA.
Ultimately, if you already have an MK3.9, you’re only missing out on minimal surface quality improvements.
MK4
Now we have arrived at the latest model in the i3 series, the Original Prusa MK4. We’ve talked about almost all the interesting features of the MK4 – namely the powerful motherboard, the Nextruder, and the color LED screen – while reviewing the upgrade kits, but there are a few characteristics that are unique to this model.
The frame of the MK4 is a beautiful aluminum cast structure with a hexagonal pattern that’s the signature of Prusa Research. Together with the slightly thicker rods on the X and Y axes, the MK4 one is sturdier than its predecessor. Furthermore, the power supply and heated bed are slightly different from the previous models, although these aren’t functional updates.
Which to Choose?
The MK4 has taken the i3 series to another level, so if you’re looking for a reliable machine that’s almost plug-and-play, this might be the right choice for you. However, if you’re looking for the best bang for your buck, you can’t go wrong with the reliable workhorse that is the MK3S+, plus you can always upgrade when you feel the need.
If you already own an MK3/S/+, you have several options. The MK3.5 kit is a great package to give new life to your machine. It contains the most significant improvements, thanks to the new motherboard, and produces noticeably better print speed and quality.
On the other hand, if you’re after the latest and greatest printing technology, the MK3.9 upgrade will get you nearly all the way to a stock MK4 kit for about $200 less. The Nextruder is a great addition to any printer, equipped with numerous sensors that provide convenience features like automatic bed mesh leveling. Průša himself doesn’t recommend the full MK4 kit – it’s so much to upgrade and you won’t save much money compared to buying the MK4 directly. However, if those VFA are getting you down, the upgrade may just be worth considering.
