Original Prusa i3 MK2S

Hello, everyone! We are on a roll this week! After releasing the exciting Smooth Variable Layer Height, I have some better news today! MK2 has been around for almost a year! Wow time flies!

The MK2’s that we are shipping now are quite a bit different than the first ones we got out the door. For example, it did not have the auto-calibration feature. Since then, almost every part has been tweaked, reinforced or optimised for better assembly. We iterated very rapidly, basically every two weeks or so. For us launching a product does not mean the job is done! If we find a way to improve it, we cannot resist. I love to believe, that this is the reason why we are successful.

MK2 life in numbers

  • ~18000 shipped
  • 10 firmware revisions
  • 5 drivers revisions
  • 5 big assembly instruction updates
  • 5 big handbook updates
  • Countless printed parts updates

Our farm has grown to 184 printers and they run 24/7 in very hot and harsh conditions, we have been collecting data and different failures which occurred throughout the year. We sat down and tried to improve everything to prevent most of these typical failures. Before I show you the details of the improvements, I just want to note that MK2S runs the same firmware and the same g-codes. The print quality is the same as with a brand new MK2 so no need to rush with upgrading. We are gradually rolling this update to the production. Price remains the same and upgrade kit from MK2 to MK2S is available for $49. Upgrade will contain smooth rods, better LM8UUs, U-bolts and misc fasteners. G-codes to print the upgraded printed parts are available. Now let’s get down to business.

Better LM8UU mounting on Y axis

On our farm, parts never cool down completely. This makes them quite hard to remove and sometimes our staff has to use excessive force. This way of removing the parts weakens the zip ties holding the LM8UUs on the Y axis and allows the whole bed to wobble. This reduces the print quality slightly. MK2S is now using U bolts to hold the bearings. From our farm experience it works very well and is quick and simple to install.

U-bolts holding the LM8UUs


Better LM8UUs and smooth rods

MK2 bearings might have been little noisy, so we sourced better bearings and rods for the MK2S. They are matched together and run very smoothly and are quieter. The smooth rods are now ground and hardened stainless steel. Igus polymer bushings upgrade is still an option for even less noise, but I think the new bearings are pretty good as they are. If you still want to upgrade, we strongly suggest to get the printer working with stock bearings first as Igus can easily bind when ever so slightly misaligned and prevent successful XYZ Calibration. BTW these better parts were used on pre-assembled printers for couple of weeks already 😉 

Better LM8UUs and smooth rods


Better P.I.N.D.A. probe mount

Loose print or overhang curling up might have broken the old mount. Not with the new one. As a bonus, the probe is much easier to adjust, just loosen the two holding screws and move it where it needs to be.

Better P.I.N.D.A. probe mount


Improved cable stress relief on extruder

If the cables were not routed to optimally on the back side of the X carriage or if some users left out the nylon reinforcement, the cables tended to break from fatigue. MK2S has reinforcements to further stress relief the cables. Improper cable management is the number 1 cause of failed probes and nozzle cooling fans which leads to clogged nozzles.

Improved cable stress relief on extruder


Better electronics cover

The most commented part of our assembly instructions was the RAMBo mini cover, more specifically that it is hard to mount on the frame. With the revised version, you can easily mount the RAMBo into the housing and just slide it onto bolts on the frame. The cable bundle from the X- carriage have been re-routed to the top now to prevent sagging of the wire harness over time.

Better electronics cover


This is pretty much it. Thank you for your continued support and always look out for new announcements 🙂 Happy printing!

You can get the upgrade pack in our eshop here and gcodes/stls are available here.




4 thoughts on “Original Prusa i3 MK2S release

  1. Hello, i would like to buy this primer frontera Argentina. Can they shipping ve done by Fedex?

  2. Dear Mr Josef Prusa,

    Honestly. I feel the need to explain my disappointment with the service I have received. I ordered a MK2s last Friday and dispite paying the additional fast delivery to receive it fast it took a week to get delivered, I had been told on several days that the unit had been shipped and when I should receive it when It hadn’t.

    Once received I built it only to find it not working because the PSU wasn’t working. Discussing this further with a support staff member, I was told I would receive it the new PSU today as it had been shipped yesterday ) Monday 28th. August. I have just been in contact with UPS to chase my package and to my surprise the replacement PSU hasn’t been shipped yet. Hopefully it will be with me tomorrow.
    Needless to say I am very very disappointed.

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