*okay let me explain 😉

The stable release of Input Shaper firmware for the Original Prusa MK4 is out now! All our new MK4 3D printers will be shipped with it by default and you can safely flash it right away to turn your 3D printing workhorse into a racehorse! 😉 The response from the community during the development was amazing and we got a ton of valuable feedback that helped us shape this release.

And the MINI just got several times faster too! Our team has done the impossible and ported the MK4 firmware to the MINI’s modest CPU and smaller RAM. With the new alpha firmware, it will feel like a brand-new printer.

So now comes the question, exactly how fast are our printers? And how do they compare to the competition?

10x Faster! 600 mm/s! 20,000 mm/s^2!

Comparing the product specifications is one of the few ways to pick between several products on the market, without getting to try them all out. Unfortunately, comparing some arbitrary number doesn’t tell you much about how fast the printer actually is.

In fact, the overall speed of a 3D printer is determined by a number of factors: print speed, accelerations, jerk speeds, volumetric flow, nozzle size, object shape and more. For marketing purposes, this is all way too complicated. So, instead, companies pick one or two numbers. Typically the travel speed, the print speed of infill, or the acceleration for printing infill.

During most prints, the printer will spend less than 10% of the time on travel moves. This means that even ridiculously fast travel moves have little impact on the overall print time. Having high acceleration for infill is certainly helpful, but the perimeters (the outside wall) are typically where all the shape complexity and changes of direction actually are. And that’s not even mentioning the fact that often these printer speeds are the “up to” values with real values in the supplied print profiles being significantly lower.

And to clear things up right away, I am not opening this topic, because our printers would perform badly in these tests. Let’s take a look at an article that was published in the New York Times which compared the print times and print quality in several different objects with four different printers – the MK4 was used with the alpha version of the Input Shaper.

In the 3 tests that the New York Times performed, the MK4 always had the shortest print time. All of the tests were performed on fairly small prints, so the length of the calibration process played a significant role in the overall print time. Had the test been performed on a different set of models, the results would have been different.

Impact of raising print speed and acceleration

The rule of diminishing returns applies even to 3D printing parameters. Raising the acceleration of print moves from 800 to 4000 will result in significantly shorter print times. Raising the acceleration from 4000 to 10,000? Not so much.

Of course, this is just one example and the difference acceleration makes is closely tied to the set print speeds. But I hope you get my point, a number being 2x bigger doesn’t mean 50% shorter print times. A decade ago I created a simple calculator to see the relationship between speed and acceleration – you can play with it here. A good starting point would be to set the distance as the size of the models you typically print – in the examples 50mm, then the speed you would like to achieve and try different accelerations.

It’s a bit like comparing two cars, one with a maximum speed of 250 km/h and the other with 350 km/h. If they are about to travel to another destination, which one will arrive first? Theoretically, it’s gonna be the one with higher top speed. But in reality? You have to take into account such variables as acceleration, traffic, fuel consumption, route taken… it’s pretty much impossible to travel at a constant max speed.

Even more things to consider – flow rates and temperature management

However, printing at high speeds requires more than just moving the extruder as fast as possible. It involves careful temperature management too.

For functional prints, where strength matters, the plastic needs to be properly melted first and then cooled after it’s extruded. Pushing the volumetric speeds too close to the limit of the hotend will result in poorly melted filament (e.g., the core will have a different temperature) which in turn affects both mechanical and visual properties.

This is rather easy to spot: if you’re using a semi-glossy filament, the printed object will be partially matte and partially glossy, with a clear horizontal border between these sections. If the volumetric flow is pushed to the absolute limit, the surface will also feature a noticeably different finish – something we call “a denim effect.” Push it a bit further and you will start seeing holes in the print. Insufficient heating or extensive cooling also results in weaker prints and worse inter-layer adhesion. Yes, even excessive cooling may compromise the quality of the print. As the extruded plastic cools down, it needs enough time for the polymer chains to orient themselves into a more ordered structure. So there’s a sort of a Goldilocks effect: not too hot, not too cool, just right. 🙂

Volumetric flow is another popular “up to” value and you can in fact check the real values in PrusaSlicer and other slicers by slicing the object and opening the Volumetric flow rate in the Legend window.

Speaking of PrusaSlicer: Our print profiles have been, for many years, tweaked for maximum quality and reliability, rather than chasing speed at all costs. And they are not just synthetic profiles. We have developed the new SPEED and STRUCTURAL print profiles with the assistance of the Prusament (Prusa Polymers) team – people with a great understanding of thermoplastics.

So how to compare the speeds of different printers?

When you’re deciding between several different 3D printers and you want to compare their print speeds, there’s nothing easier than downloading their respective slicers and checking the speeds yourself. PrusaSlicer has an exceptionally accurate print time estimation, so all other slicers based on PrusaSlicer (SuperSlicer, Bambu Studio, AnycubicSlicer, OrcaSlicer, etc.) will also have an accurate print time estimation. For slicers based on Cura (e.g. Creality Slicer), the estimates should also be fairly accurate, as long as the acceleration and jerk settings match the values in the firmware of the printer.

You can slice the typical object that you plan to create with your 3D printer in all slicers and compare the estimated print times. Plus, you can also check whether the number in the print profile actually matches the number claimed by the manufacturer. This way, you can see whether there might be a catch or two – like  to achieve the advertised speed. If you read the small print, you may realize that, e.g., the print speed for PETG is less than half of the claimed theoretical speed.

Needless to say, even the slicer estimates are not the perfect way to compare 3D printer speed. The shape of the 3D model, the used filament, the nozzle, and the environment… they all play important roles and as a result, the relative print times of each specific print will be different.

With all of that said: the print speed is just one of the important aspects of a 3D printer to consider when comparing various models. There are other things to consider, such as print quality, reliability, ease of maintenance, tech support, community, (open-source) software, sustainability, or filament waste during multi-colored printing. But also things like upgradability and continuous support even years after release. Which brings me to this:

MINI Input Shaper is here!

Call us old-fashioned, but we’re not gonna make you buy a new printer every two years. In fact, we’re doing everything we can to let you keep your existing printer and make it better and better.

This is why we have just released a new firmware for the Original Prusa MINI/MINI+ which essentially turns this printer into a compact speed demon. 🙂 Our devs managed something that seemed almost impossible – they ported the MK4 firmware to the less powerful platform of the MINI and brought all the amazing features like Input Shaping, Pressure Advance and networking to MK4’s sibling.

The alpha version is out now and if you feel a bit adventurous, give it a try! Many users already did and they are excited about the massive speed increase – it just feels like an almost new printer. Plus, you can easily connect the MINI to Prusa Connect and send files directly to the printer without the need to run around with a USB drive. The stable version should be available within approximately one month.

Below is a video in which I tried to pull the fastest possible Benchy on the MINI – not following the rules of speedboat race, but a nice visual demo of how fast can the printer go. With SpeedBenchy rules, the Benchy currently takes 26 minutes to print.

And we’re not done yet! We have more exciting updates in the pipeline – we’ll share the details in a few weeks.

XL Input Shaper is almost ready

Now, the obvious question is: what about the XL? First: a different dev team manages the XL firmware in a dedicated code branch, so it’s not the same as the MINI. This is due to the completely different CoreXY kinematics and the presence of a toolchanger which brings additional challenges. While the CoreXY system usually allows for higher speeds, the larger the printer is, the longer the belts are – and longer belts stretch and flex more than shorter ones which may negatively affect the print quality. So that’s another thing we’re taking into account.

We’re getting ready for the first release of the Input Shaper firmware and testing is fully underway. We expect to have the alpha version ready in October (initially just for the single-tool).

Happy (and fast!) Printing!