RE: 6.4.0-RC Firmware for Prusa CORE One
Auto open/close Vent is not fully working. Opens or closes the Vent only after power up / start first print.
After print it is not closing the vent, what would be a good idea because of dust can come in
I guess you could still use the custom start and end Gcode, as in the original community version: https://www.printables.com/model/1323846-core-one-automatic-chamber-vent
RE: 6.4.0-RC Firmware for Prusa CORE One
@hyiger
Nice, super interesting. The most exotic thing I've printed on my printers is PC-CF and PETG-CF. I'd 400C nozzle is pretty darned hot. What bed and chamber temps do those materials you're talking about need. All the stuff inside that enclosure we need to be able to stand up to the increased temps.
RE: 6.4.0-RC Firmware for Prusa CORE One
Vanilla out of the box, batch 3
@huskyte
was your core one upgraded from an MK4S, built from kit, or pre-assembled? I'm curious if any issues are folks are having with core one are related to reusing some components from MK4S upgrade etc. My core one was upgrade from MK4S, so reuses the heatbed, powersupply and main board from the MK4S. Other than initial issues I had after I just built it, it's reasonaably solid for rigid filaments using the 6.3.4 firmware. I prints 92A+ tpu ok, with the bogie mod in the extruder(to prevent filament winding around the extruder gear). I haven't had any other issues with it. But I also haven't tried any of the 6.4.x RCs either. I could see issues with new/older parts causing variation in behavior. Just random thought on my part.
RE: 6.4.0-RC Firmware for Prusa CORE One
I'm curious if any issues are folks are having with core one are related to reusing some components from MK4S upgrade etc.
I think there are just several aspects of the Core One design which are a bit "on the edge". It probably depends more on luck whether they work or cause problems, than whether the printer was factory-built, a full kit, or an upgrade:
- Long ribbon cable to the display, maybe even more problematic because it runs along the stepper motor cables, can cause display malfunction at full data rate.
- Cable routing in the umbilical cord to the print head, which may cause excessive crosstalk from heater to load cell.
- No defined grounding path for the XY stepper motor chassis; if the paint layer is intact, lack of grounding causes static buildup and crashes.
- Precise sensing of home position via motor stalling depends too critically on the bumping pattern, and hence gantry alignment.
- ... and probably a few more I can't think of at the moment.
The "different pitches in the three Z lead screws" may be exclusive to full kits and upgrade kits, since they combine motors from different manufacturing lots. (Two from the MK4S or the pre-packaged motor kit, one extra.) In contrast, I assume Prusa technicians get three Z motors from the same shelf when building printers in the factory.
Mine was update from 3.9s parts. No electrical problems whatsoever. Homing was a different problem though and I spent several hours on line with support and it tuns out it was none of the things they suggested and we tried. The answer was mismatched steppers! 200 and 400 steps per rev steppers simply don't work together.
One problem I have, and is still ongoing is loading filament - It has a habit of not feeding down the tube on the nozzle and failing ramming. Never happened previously and I can see, potentially, where the problem lies. The supplied Prusa part is poor. The sloping slot on the part the nextruder mounts to doesn't line up properly with top of the filament tube. I need to print another when I get around to it. Fortunately I don't change filament that often and often use a roll fully and dread frigging about when I do! I blame this on two blocked HF nozzles I have where the filament has baked solid in the end and I've had no joy in clearing them! Back on CHT brass nozzles which do clear with a cold pull when blocked. I may install my V6 nozzle adapter as a last resort as I'm out of expensive ones and I've lots of V6 nozzles in stock.
RE: 6.4.0-RC Firmware for Prusa CORE One
Wouldn't this just be end and start gcode?
print end: always close
Print start: if set temperature above 30 close the gates
Auto open/close Vent is not fully working. Opens or closes the Vent only after power up / start first print.
After print it is not closing the vent, what would be a good idea because of dust can come in
RE: 6.4.0-RC Firmware for Prusa CORE One
Wouldn't this just be end and start gcode?
print end: always close
Print start: if set temperature above 30 close the gates
Auto open/close Vent is not fully working. Opens or closes the Vent only after power up / start first print.
After print it is not closing the vent, what would be a good idea because of dust can come in
RE: 6.4.0-RC Firmware for Prusa CORE One
I'm in no rush, but just curious when this RC might actually be released? RC originally came out. around 11/23/2025 so we are almost 2 months at this point.
Summary
- New features
- Nozzle cleaning failed wizard
- Fixes
- Fix #4816
This is the release candidate for the upcoming firmware 6.4.0 for the Prusa CORE One, MK4S, MK4, MK3.9S and MK3.9. It reunifies the firmware development branch after the temporary split during the CORE One launch, where 6.3.x was released exclusively for CORE One and other printers remained on 6.2.x – along with bringing new features, improvements, and fixes across all platforms.
Builds for XL, MINI, MK3.5S and MK3.5 are temporarily not included due to identified issues currently under investigation.
For a complete overview of features introduced in firmware 6.4.0, users can refer to the 6.4.0-alpha release notes published earlier.
Nozzle cleaning failed wizard
The recovery process for failed nozzle cleaning has been reworked into a new step-by-step wizard. It replaces the previous purge option introduced in 6.4.0-alpha.
The wizard also includes a filament retraction step to prevent oozing before retrying the automatic cleaning sequence, increasing the chance of successful recovery.
Release notes:
https://github.com/prusa3d/Prusa-Firmware-Buddy/releases/tag/v6.4.0-RC
RE: 6.4.0-RC Firmware for Prusa CORE One
RC2 is available: https://github.com/prusa3d/Prusa-Firmware-Buddy/releases/tag/v6.4.0-RC2
I suspect there will be an RC3 or 4 even. Still bugs...
RE: 6.4.0-RC Firmware for Prusa CORE One
RC2 is available: https://github.com/prusa3d/Prusa-Firmware-Buddy/releases/tag/v6.4.0-RC2
I suspect there will be an RC3 or 4 even. Still bugs...
Loaded it two days ago, Core One, and done a few prints and its behaved so far. Not changed filament yet though, but I believe bed dropping is still happening randomly. One thing I looked at was the strobe type tensioner and couldn't see the effect, belts were vibrating and turning knob made it change tone but couldn't see any strobe movement? It's working fine so aborted it.
None of the new listed bugs apply to me, don't use phase stepping and door sensor disabled. Which bugs are you referring to?
RE: 6.4.0-RC Firmware for Prusa CORE One
One thing I looked at was the strobe type tensioner and couldn't see the effect, belts were vibrating and turning knob made it change tone but couldn't see any strobe movement? It's working fine so aborted it.
How did you confirm that "the belts were vibrating"? Did you see the slow transverse vibration under the stroboscope light, or did you just judge by sound or by touching the belts?
If you did not see any transverse motion (with a peak amplitude of a few mm, so you can't miss it when you are in the frequency ballpark), then the frequency you had set on the dial was significantly off target -- i.e. the belt tension may be significantly too high or too low. If you did see it, you should also see a clear amplitude change when you tune up or down 1..2 Hz via the dial, letting you find the frequency which gives maximum amplitude.
RE: 6.4.0-RC Firmware for Prusa CORE One
One thing I looked at was the strobe type tensioner and couldn't see the effect, belts were vibrating and turning knob made it change tone but couldn't see any strobe movement? It's working fine so aborted it.
How did you confirm that "the belts were vibrating"? Did you see the slow transverse vibration under the stroboscope light, or did you just judge by sound or by touching the belts?
If you did not see any transverse motion (with a peak amplitude of a few mm, so you can't miss it when you are in the frequency ballpark), then the frequency you had set on the dial was significantly off target -- i.e. the belt tension may be significantly too high or too low. If you did see it, you should also see a clear amplitude change when you tune up or down 1..2 Hz via the dial, letting you find the frequency which gives maximum amplitude.
They were vibrating, touched them. According to several other methods they are about 4Hz higher than Prusa recommend. Done for a reason as recommended moons ago to stop head beating itself to death homing and failing miserably.
RE: 6.4.0-RC Firmware for Prusa CORE One
RC2 filament madness - Changing filament is crazy! Printer turned off after last print and bed is just below slope of side panels. Turn on and select unload filament, bed moves down 40mm and unloads. Insert new filament and as soon as filament passes first sensor bed starts moving down a further 40mm. As purge starts it moves down again and ends up 20mm off base of printer. Checking, printer thinks Z is at 80mm !! - Printer should home and know where it is on power on like 3 and 4 series did IMO
RE: 6.4.0-RC Firmware for Prusa CORE One
[...] bed moves down 40mm [...]
Yes, I found that annoying too -- the bed moves down (to safeguard against crashes? to provide easy manual access?) on too many occasions, and repeatedly. It is easy to have it run into the bottom end stops, losing its position. Not sure whether that behavior is new with 6.4.0 though?
I am not sure what behavior I would prefer instead. Automatically homing upwards to touch the nozzle can take a long time, depending where the bed starts. Should that really occur automatically on every start?
RE: 6.4.0-RC Firmware for Prusa CORE One
[...] bed moves down 40mm [...]
Yes, I found that annoying too -- the bed moves down (to safeguard against crashes? to provide easy manual access?) on too many occasions, and repeatedly. It is easy to have it run into the bottom end stops, losing its position. Not sure whether that behavior is new with 6.4.0 though?
I am not sure what behavior I would prefer instead. Automatically homing upwards to touch the nozzle can take a long time, depending where the bed starts. Should that really occur automatically on every start?
Moving, even from Z max only takes a few seconds? Problem is printer has no idea where it is on power on and only homes on starting a print. It's clueless otherwise. It was allegedly fixed from RC to RC2, obviously not. Bug Reopened #4868. I've added this in a post on github which 3d-gussner is dealing with
RE: 6.4.0-RC Firmware for Prusa CORE One
Moving, even from Z max only takes a few seconds? Problem is printer has no idea where it is on power on and only homes on starting a print. It's clueless otherwise. It was allegedly fixed from RC to RC2, obviously not. Bug Reopened #4868. I've added this in a post on github which 3d-gussner is dealing with
But an automatic homing is not entirely safe either. If the toolhead is all the way in front it might miss the bed. Or if the prior print is still on the bed you could get unpleasant crashes if that print bumps into anything else than the nozzle & load cell.
Moving the bed all the way down would be the safe alternative. But without active sensing it causes unpleasant noises and a loss of the exact position information, so it's not an option in the Core One I think.
RE: 6.4.0-RC Firmware for Prusa CORE One
Thumbs up: RC2 installed (Core One per the subject line) and working.
RE: 6.4.0-RC Firmware for Prusa CORE One
Moving, even from Z max only takes a few seconds? Problem is printer has no idea where it is on power on and only homes on starting a print. It's clueless otherwise. It was allegedly fixed from RC to RC2, obviously not. Bug Reopened #4868. I've added this in a post on github which 3d-gussner is dealing with
But an automatic homing is not entirely safe either. If the toolhead is all the way in front it might miss the bed. Or if the prior print is still on the bed you could get unpleasant crashes if that print bumps into anything else than the nozzle & load cell.
Moving the bed all the way down would be the safe alternative. But without active sensing it causes unpleasant noises and a loss of the exact position information, so it's not an option in the Core One I think.
The X/Y axis are homed first and move to a position over the bed itself. The Z moves up until the nozzle is sensed, then it raises, moves to a position over the corner of the bed (testing a bed is there) and raises again. IF it misses the bed - it fails and wont proceed until it is homed properly and senses a bed. Automatic homing is perfectly safe. Try it..
RE: 6.4.0-RC Firmware for Prusa CORE One
Thumbs up: RC2 installed (Core One per the subject line) and working.
RE: 6.4.0-RC Firmware for Prusa CORE One
Thumbs up: RC2 installed (Core One per the subject line) and working.
BUT - there are a few bugs still outstanding I've come across today that were reported as fixed! One is multiple unnecessary Z axis moves downward especially during unload/load filament which can cause Z axis crash into base of printer and annoying pulsing of extruder fan even when idle and nozzle temp has dropped below threshold. I'll no doubt find others in time..
RE: 6.4.0-RC Firmware for Prusa CORE One
@steve-33
Thanks for being brave enough to test it for me so I don't have to 🙂 I have three different prusa printers to consider and I'm curious when the firmware version will be unified for them again.