Problems with my brand new Core One - Assembly and first prints troubleshooting

RE: Problems with my brand new Core One USB/File error

AndyM — Fri, 31 Oct 2025 20:49:32 +0000

Since building my Coreone a few weeks ago, I have had persistent error messages - file or USB error.I investigated the USB mechanical interface and there were no issues, then I remembered that I had problems with stripping the thread by the Faston connector, during construction of the front panel assembly. The tab adds significant thickness and the screw and socket are not long enough. I decided to solder the tab directly to the PCB. I put some filament into the screw hole and I also added an M4 washer on the opposite side of the back, because otherwise it is crooked when fixed to the metalwork. I reassembled the front panel and this appears to have solved the problem as I have not seen the error message since. I guess that the lack of a secure ground point makes the ribbon cable more susceptible to interference from motors etc.

RE: Problems with my brand new Core One

henri — Mon, 12 May 2025 13:21:18 +0000

Hi,

I posted some of my problems weeks ago. Since the printer was faulty upon reception on several aspects, I decided to return it.

I started the return procedure, and sent a link to pictures of the packaging procedure. It was on May 5th.

But I haven't received anything from the support since that. I sent the email again on May 8th, without any answer.

Could you tell me how long you waited before having the printer taken ?

Thanks

RE: Problems with my brand new Core One

JCDrew — Sun, 04 May 2025 17:31:59 +0000

I just went through the exact same issue. I agree with the comments that the USB drives that come directly with the Core ONE are suspect at best. of course, most modern machines will not format in FAT32, they want to use exFAT or NTFS. I tried everything under the sun to get it to work and the only solution was to find an old USB stick that was formatted with FAT32. I copied my files and the latest firmware update and plugged it in. Everything worked just as expected.

by the way, I absolutely love this printer.

RE:

henri — Thu, 24 Apr 2025 14:09:36 +0000

Thanks for your suggestion. Unfortunately, I will stop trying to use this printer, and asked for a refund. Prusa has been a well know firm for a long time, in the range of printer that you have to tweak and improve yourself before having a reliable printer. It is my mistake to think that they can produce a printer that is well designed and reliable without having to adjust it.

RE:

LarGriff — Thu, 24 Apr 2025 13:59:49 +0000

This from @vhubbard - https://www.hubbardhobbies.com/3dprinting/3D-printingnotes.html

The cheap USB sticks that come with the MK4 printer tend to have problems and are often replaced. It is easy to get a good, quality replacement. Make sure the new USB thumb drive is USB2, NOT USB3, 3+ etc. Through harsh experience I learned that a USB3 drive may cause severe problems with WIFI based file transfers. Prusalink, Pusaslicer and Prusaconnect all had problems with file transfer failures when using a USB3 thumb drive. I have used multiple USB2 drives with no WIFI based file transfer problems. Recommendations for the MK4 USB thumb drive:

USB2 32GB or smallerFormatted for FAT32 Allocation size when formatting, 4096, a personal preference for the 3D printers.

RE: Problems with my brand new Core One

henri — Thu, 24 Apr 2025 13:54:17 +0000

Hi Jürgen,

I don't think so, but I will check. As I installed a firewall for my domestic network (I was a lecturer in Computer Architecture in a previous life), I remove any form of firewall on my Windows computers. And after checking, my USB key does not contain any strange file.

Do you know that when you return a printer that fails upon reception for refund, Prusa will not pay the shipping costs ?

RE: Problems with my brand new Core One

Jürgen — Thu, 24 Apr 2025 13:25:23 +0000

@henri-2, the trouble with the smaller sticks is surprising. Do you possibly have some 3rd party security software (anti-virus) on your Windows machine which decides to install some hidden files on the USB stick upon formatting?

RE: Problems with my brand new Core One

henri — Thu, 24 Apr 2025 13:17:49 +0000

Actually, I use several USB keys before trying a cloning:

- one "generic" 16GB: failed

- one "32GB Kingston Data Travaler": failed

- the 64GB SanDisk. But as I cloned the Prusa USB Key on it, it is seen as a 32GB USB key, in FAT32.

@Kachidoki: I used a PC with Windows 10 to format the keys. And I doubled checked the format chosen, since the first key I tried was refused.

Thanks for your help.

RE: Problems with my brand new Core One

Jürgen — Thu, 24 Apr 2025 13:09:23 +0000

Posted by: @henri-2
I tried the following things before my conclusion (I can be wrong, of course):
64G USB3 SanDisk Ultra Media USB key:
- formatted using a regular PC with Windows 10: failed

I thought you were using a 16 GByte USB, according to your first post above? 🙄 That has set us on the wrong track, I guess.

64 GByte formatted with Windows is known not to work. As @kachidoki said, Windows will not use regular FAT32 formatting for large volumes, but will decide to use ExFAT (without telling you). Use a smaller stick; or format with Linux or a dedicated tool; or clone the volume from a smaller stick, as you did.

RE:

Kachidoki — Thu, 24 Apr 2025 11:55:07 +0000

Hmmm, my feeling as a developer: are you sure it's FAT32 that is used by windows format tool for a media >32GB? I guess it is exFAT.

You probably need to use an alternative tool or a real OS to format properly your USB key. I use Sandisk UltraFit flash drives, but 32GB max, which is already really plenty!

https://help.prusa3d.com/article/sd-cards-and-usb-drives_112291