6.4.0-RC Firmware for Prusa CORE One - General discussion, announcements and releases

RE: 6.4.0-RC Firmware for Prusa CORE One

ssill2 — Thu, 04 Dec 2025 16:14:27 +0000

I think I can reliably recreate the case where selected tool head 2+ crashes into into a parked tool 1. It's happened to me twice now, on 6.2.6 firmware and I have no reason to suspect it would be improved in 6.4.0 firmware. I've been doing a 5 color tpu print. In a few cases I've needed to cancel the print. If I cancel the print while a tool such as 2 is the one currently used, it stops the print and moves the toolhead back to the left rear corner. I you then go to menu and choose to unload that filament, tries to move that toolhead into the parked toolhead 1. It then tries to home itself and continues normally. that seems like bad behavior

RE: 6.4.0-RC Firmware for Prusa CORE One

hyiger — Tue, 02 Dec 2025 14:57:15 +0000

Posted by: @steve-33

Posted by: @hyiger
Posted by: @jurgen-7
Tread carefully... this is an emotional topic for Steve. 😉
IDK. Don't shoot the messenger maybe?
I think the bug before was that if you change the filament and for whatever reason you needed to try again, the bed would move down again. That's why it is supposed to auto home first on a filament change. Unless I'm missing something...
I can understand the Homing XY and moving the Z down a little once - but four times for total of 110mm???? (I cant call it stupid as jurgen may cry 🤣)

Yes. As I said (or maybe I didn't directly) it was reported awhile back as a bug.

RE: 6.4.0-RC Firmware for Prusa CORE One

Jürgen — Tue, 02 Dec 2025 10:58:45 +0000

Posted by: @steve-33
(I cant call it stupid as jurgen may cry 🤣)

You can call the printer stupid as much as you like. But I would appreciate if you refrain from calling users stupid because they have different usage scenarios than you.

RE: 6.4.0-RC Firmware for Prusa CORE One

Steve — Tue, 02 Dec 2025 10:52:33 +0000

Posted by: @hyiger
Posted by: @jurgen-7
Tread carefully... this is an emotional topic for Steve. 😉
IDK. Don't shoot the messenger maybe?
I think the bug before was that if you change the filament and for whatever reason you needed to try again, the bed would move down again. That's why it is supposed to auto home first on a filament change. Unless I'm missing something...

I can understand the Homing XY and moving the Z down a little once - but four times for total of 110mm???? (I cant call it stupid as jurgen may cry 🤣)

RE: 6.4.0-RC Firmware for Prusa CORE One

gb160 — Sun, 30 Nov 2025 13:27:15 +0000

Posted by: @ssill2
The head crash I saw on the XL was when canceling prints. the two color prints I was doing in PLA went perfectly fine. Printing with ninjaflex, or tpu in general usually requires a couple cancelled prints until I get things dialed in, so it's not an edge case for me at all.

Exactly the same situation with me any the C1.
Surpised no-one else with a C1 is reporting it. It's not as dramatic on the C1, it crashes the toolhead into the X limit in the back right corner. Only slightly, but I recognise the sound when the motor misses steps.

RE: 6.4.0-RC Firmware for Prusa CORE One

ssill2 — Sun, 30 Nov 2025 12:58:00 +0000

The head crash I saw on the XL was when canceling prints. the two color prints I was doing in PLA went perfectly fine. Printing with ninjaflex, or tpu in general usually requires a couple cancelled prints until I get things dialed in, so it's not an edge case for me at all.

Posted by: @kachidoki
I have made several prints mixing two-color PETG with PLA supports on the XL with this firmware. There are some strange behaviors regarding the automatic retraction feature that I have not yet investigated, but printing and parking work well. I have never experienced a print head collision since I got the printer.

RE: 6.4.0-RC Firmware for Prusa CORE One

Kachidoki — Sat, 29 Nov 2025 19:46:14 +0000

I have made several prints mixing two-color PETG with PLA supports on the XL with this firmware. There are some strange behaviors regarding the automatic retraction feature that I have not yet investigated, but printing and parking work well. I have never experienced a print head collision since I got the printer.

RE: 6.4.0-RC Firmware for Prusa CORE One

ssill2 — Sat, 29 Nov 2025 17:25:23 +0000

I would concur. on my CoreOne and my MK4S it seems fine. Just not on the XL. I'm curious how stable the 6.5.1 firmware is on the core one L lol. I've not been checking out that forum yet.

RE: 6.4.0-RC Firmware for Prusa CORE One

hyiger — Sat, 29 Nov 2025 17:21:04 +0000

Unless you have an XL, this firmware seems stable enough for a Core One and, so far, fixes issues with nozzle cleaning failures, less aggressive homing and a much more convenient way to tune the belts. I haven't had any failures (BSOD's or otherwise) during a print in the last 2 months.

RE:

mnentwig — Sat, 29 Nov 2025 16:41:43 +0000

>> Prusa had a reliable reputation for shipping broken firmware

I considered for a second an "unreliable" reputation for shipping broken firmware but it gave me a headache... Well at least while I'm writing this, the printer is printing happily... hey what's that noise ...

EDIT "that noise" was noises of a core one while printing happily... just for the record :D