6.3.4-RC Firmware for Prusa CORE One
Summary
- Smarter heat absorption logic
- Retuned heatbed PID for thermal stability
- Automatic display refresh rate fallback
- Additional updates, improvements, and fixes
This is the release candidate for the upcoming firmware 6.3.4 for the Prusa CORE One, addressing several improvements and bug fixes.
This release focuses on enhancing reliability and fine-tuning the user experience based on recent feedback and internal testing. Users can expect smoother operation, better thermal stability, and quality-of-life improvements across multiple areas of the firmware.
Smarter heat absorption logic
The heat absorption logic has been significantly improved to make your printer smarter — and your workflow faster. The firmware now continuously tracks recent heatbed activity and dynamically adjusts the required stabilization time before printing. If the bed has already been heated, such as when printing multiple objects in succession, switching materials, or using preheat, the usual heat absorption delay is automatically shortened — or even skipped entirely.
This leads to a noticeably faster transition into printing, especially during reprints or tightly timed jobs, helping you save time, stay productive, and get the most out of every print session.
Retuned heatbed PID for thermal stability
PID values for the CORE One heatbed have been fine-tuned to provide more stable temperature regulation and improved print consistency.
Automatic display refresh rate fallback
If repeated display anomalies (such as flickering) are detected, the printer now shows a prompt offering to switch to a lower refresh rate. To ensure the dialog remains readable even if the display is unstable, the system temporarily applies the lower refresh rate before displaying the prompt. If the user selects "No," the original (higher) refresh rate is restored.
The display refresh rate can also be adjusted manually at any time in Settings → Hardware → Display Refresh Speed.
Additional updates, improvements, and fixes
Progress reporting during filament auto-retract
The progress bar is now updated during the auto-retract phase of filament load or change, instead of remaining stuck at 99% in the "Loading" phase.
Option to disable grille check warnings
The ventilation grille warning now includes a “Disable” button. The warning can also be managed under Settings → Hardware → Check Ventilation Grilles.
N/A entries removed from print carousel
Print screen carousel now omits entries marked as “N/A” to reduce clutter and improve readability.
Increased retraction after filament change
Retraction during filament unparking has been increased from 2 mm to 4 mm to minimize oozing.
Extended post-print filtration limit
The maximum setting for post-print air filtration has been extended from the previous limit to 90 minutes.
Phase stepping calibration option
A calibration option is now available to fine-tune phase stepping on the CORE One. The feature requires a PRUSA Accelerometer Set and is intended for advanced users who enjoy exploring deeper tuning options and experimenting with motor behavior.
Chamber lights stay on with the camera enabled
When the integrated camera is active, chamber light dimming is now disabled by default to maintain optimal visibility. This behavior can still be manually changed in the settings.
Nozzle no longer heats unnecessarily on unload
The nozzle will no longer be heated unnecessarily during filament unload if the filament has already been auto-retracted and only needs to be deretracted for gear clearance.
Nozzle now cools properly after unloading
After filament unload, the nozzle now properly begins the cooldown process.
Corrected door sensor calibration instructions
Corrected the wording in the door sensor calibration wizard. The prompt now properly instructs the user to loosen the tensioning screw, not tighten it.
Release notes: https://github.com/prusa3d/Prusa-Firmware-Buddy/releases/tag/v6.3.4-RC
RE: 6.3.4-RC Firmware for Prusa CORE One
Nice to see phase stepping making an appearance! I've previously run the wizard a few times and it's been unable to obtain a result. It wasn't clear whether that was because something went wrong, or because it just wasn't able to make an improvement. I wonder if that situation has changed - maybe the message at the end has been updated if the latter, or the reliability with edge cases improved if the former.
RE: 6.3.4-RC Firmware for Prusa CORE One
Great news. Eager to get the final release. Most of the issues are on the list. Thanks's for this update. 😀
RE:
Thank you, that list includes a few long-awaited improvements. But it seems that the "head-banging" calibration issue has not been addressed, and neither the interference of the hotend heater with Z probing which some users experience, right? And no news on minimizing VFAs yet?
RE: 6.3.4-RC Firmware for Prusa CORE One
Happy to report phase stepping has reduced the noise of my MK4S > Core One SIGNIFICANTLY. It's not MK4S quite (and may never be?) but wow massive improvement. If you're printer sings/resonates/"talks" to you - this will reduce the noise to more or less the fans and the normal "whine" of the motors. Printing a VFA test shortly and will report back. This update has reduced the head banging for me - it'd do it maybe 10-15 times? or more before? and now maybe 2-4? Not gone, but way better for me anyway.
RE:
Do we have any indication what the phase stepping calibration is actually going to resolve?
RE: 6.3.4-RC Firmware for Prusa CORE One
Please see the blog they made when they published it for the XL: blog.prusa3d.com/phase-stepping-how-we-busted-vibrations-and-improved-print-quality
RE: 6.3.4-RC Firmware for Prusa CORE One
I tried to tune phase stepping on my freshly built CORE One and it didn't change anything. Same resonance noises at 80mm/s. So disappointed...
RE: 6.3.4-RC Firmware for Prusa CORE One
Can you locate where the noise comes from?
On my XL phase stepping was a nice improvement. The focus is on quitening the steppers themselves. And there are still a few movements you can hear, especially quick back and forth ones at base infill. Mainly because of the reaction forces of the extruder onto the frame which then shakes on its feet. The XL's dockable nextruder are very heavy. Even without the x-carriage they weigh a whopping 550 g. Please note that I did not bother to put the side panels to the printer. The thin and straight base plate acts as a noise amplifier as well. I recently put 2 printed bars below it that sort of pretensioned it. That mitigated the noise.
I have not yet listened more closely to our Core One in the company. Until now, I dit not notice any resonance noise. I can imagine that the thin panels, held only by the quick fasteners may be prone to vibrations. Maybe other fasteners or some thin but elastic tape on the support faces can help.
RE: 6.3.4-RC Firmware for Prusa CORE One
VFA's have improved for me -not a lot but a little. Still a long way to go it would seem. I also continue to have the corner banging - the first print after upgrade only did it a few times, but a few prints since and it's doing it a ton and even failing at times. Never had a failure when on 6.3.3....
RE: 6.3.4-RC Firmware for Prusa CORE One
VFA's have improved for me -not a lot but a little. Still a long way to go it would seem. I also continue to have the corner banging - the first print after upgrade only did it a few times, but a few prints since and it's doing it a ton and even failing at times. Never had a failure when on 6.3.3....
Search for the custom Start G-Code with M104 S0 above the G28 and G29 commands (homing, nozzle cleaning, MBL).
If your Core One doesn't bang its head, when you run the "Auto Home" from the LCD - > Control without pre-heating, then the M104 command to disable the hotend heating can solve a lot of the issues during the starts of a print.
If the auto home fails or bangs more than the normal ~8 times in the corner (without pre-heating!), then it's a gantry/belt tension problem.
RE: 6.3.4-RC Firmware for Prusa CORE One
Just to confirm, do we need the accelerometer to run the phase stepping calibration?
RE: 6.3.4-RC Firmware for Prusa CORE One
Just to confirm, do we need the accelerometer to run the phase stepping calibration?
Yes 🙂
RE: 6.3.4-RC Firmware for Prusa CORE One
The feature requires a PRUSA Accelerometer Set
RE: 6.3.4-RC Firmware for Prusa CORE One
Ordered from Printed Solid “Prusa USA” (whom I have to say was not impressive on my first purchase).
Lets see if it makes a difference on a Prusa (Czech Republic) assembled printer.
RE: 6.3.4-RC Firmware for Prusa CORE One
VFA's have improved for me -not a lot but a little. Still a long way to go it would seem. I also continue to have the corner banging - the first print after upgrade only did it a few times, but a few prints since and it's doing it a ton and even failing at times. Never had a failure when on 6.3.3....
Running a print test now! Let’s see!!
RE: 6.3.4-RC Firmware for Prusa CORE One
Does disable dimming only work with the Buddy cam? I have a Unifi G4 Instant hooked up and the auto-dimming is still happening while I'm printing.
RE: 6.3.4-RC Firmware for Prusa CORE One
I updated the printer, did the phase stepping calibration and recalibrated the input shaper, reduced some of the VFA, but the printer became much quieter.
RE: 6.3.4-RC Firmware for Prusa CORE One
And if you need the accelerometer, here's a useful accessory for it.
RE: 6.3.4-RC Firmware for Prusa CORE One
I updated the printer, did the phase stepping calibration and recalibrated the input shaper, reduced some of the VFA, but the printer became much quieter.
I updated the firmware and printed some new feet for the printer using PETG Ultramarine Prusament (which really shows the VFA).
I found that the VFA was very pronounced with certain settings vs others. Generally, there was a slight improvement.
I've ordered the accelerometer from Prusa USA (Printed Solid) and I'll see what that calibration does.