Yes, I’ve owned a Core One for a few days now. I’ve run several MK3 and MK3S printers over the past 7 years, and the feeling grew stronger: I needed something new! The printer arrived 2 weeks earlier than promised by Prusa. I ordered it factory-assembled.
Why the Core One?
To be honest, I was looking at a Voron. And no, I wasn’t even considering that walled-garden stuff called Bamboo… However, the Core One had all I wanted to have, and Prusa got quite some Credit in their account. Open-source features, good prints out of the box, responsive support, and a vibrant community. And yes, it comes for a price!
My tales …
After it arrived, I unpacked the monstrosity (heavy weight …), ran through calibration, did a test print, and then the problems started… one after another. I’m listing them here, including the solutions—if I found one. No solution means the issue is still there…
„Cleaning nozzle failed“
The second print started, the printer was heating up, and then it stopped working with this error. However, the nozzle was clean. OK, I found other users reporting this and pointing to it
https://www.printables.com/model/1262695-core-one-nozzle-wiper-remix
Solution: works great!
„Ventilation grille“ and „Clear print bed“
Prusa seems to think all its customers are unable to breathe on their own. They started with those stupid user prompts a while ago. And with the Core One they took it to the extreme. You will see a lot of stupid warnings, or warnings that you might welcome once, but never need to read again. Come on: telling me I need to clear the print bed on starting a new print job?
The ventilation message blocks the display, by the way. But you go on with printing, by ignoring this stupidity.
Solution: none—just a feature request to be able to switch this behaviour off.
Wrong homing, firmware crash
I found myself caught in a loop. My printer was cold, filament was loaded. I powered it on, and pressed „Unload Filament“. It asked me for the material, and I selected ASA. The printer warmed up, and started homing. Sounds good so far, right?
Just, the printer kept running its homing sequence, and never left it. It seems the firmware is waiting when the required temperature was reached.. However, for ASA this can take a while … the printer crashed, reboot, and brought up a red warning about belt tension. I was not able to help myself except by hitting reset. Then I started heating for ASA, and started the Unload filament when I hit the temperature needs.
Solution: None so far. You can workaround the situation as described, and there is a GitHub issue for this.
Belt tensioning
First of all, I was checking the belts when I unpacked the machine the other day. It felt reasonable. And I wouldn’t have expected anything else for a factory assembled machine.
However, in the chapter above the machine was complaining. So I started reading the manual on how to check and adjust belt tension. I installed the Prusa app, and went to the printer. After starting the app, it asked me for my Prusa account. Wait—I just want to check belt tension, not deal with all the Prusa Connect stuff. Still – your Prusa account, please!
All Europe: GDPR! Prusa: yes …
OK, playing guitar on the belts as described in the manual, and their app shows values between about 50 Hz and 175 Hz, while the tone isn’t changing at all. Seems, the apps frequency measuring is causing more problems than it can solve. I switched to another app, called Audio Spectrum analyzer, it is available on FDroid for free, and respects your privacy.
Needless to say: the belts were both swinging at around 85 Hz, as requested. So, I do not know why the machine came up with the request for belt tensioning. Maybe the bug hunt is bringing something to light …
Solution: not needed, Belts were OK.
Prusalink crashes, becomes unreachable
I was in the middle of a print, when I prepared the next one by uploading some G-Code to the printer. Suddenly, the upload stopped, the progress would not update. API was unreachable as well, and refreshing the whole page resulted in an unreachable page error.
The print continued …. nice!
The Prusalink and API came back online without anything done by me, on its own.
Solution: patience… it took about 20 minutes to solve on its own
Octoprint
I’m an Octoprint user for years. And I want to use it with my new printer, too. Just, there is no reliable information how it works or how to set it up for this machine. I found forum entries stating it ‚runs hassle-free‘, while others were complaining.
Solution: wait …
UPDATE 2025-06-06: Octoprint is working now. It was so easy, once I found this post here:
https://www.reddit.com/r/octoprint/comments/1kqc0ha/profile_settings_for_prusa_core_one/
Just use the lower USB-Port at the back of the printer. On top, I checked the Heater Chamber checkbox, different to what the Reddit post was recommending.
Summary so far (2025-05-17)
Mixed feelings. Yes, I was kind of early with my order. On the other hand, the machine has been on the market for several months, and I paid „release money“, not „beta money“ for it. I am hoping for some of the things getting fixed soon! Others, I can work around.
The idiotic „I take care of you“ messages and dialogues are a true fun killer, Josef! Why can’t you just provide a setting so experienced users can switch off this noob warnings?
