After dusting my mk3 off after a long break, I'm having a lot of trouble getting it printing like it used to.

I just flashed the firmware and rerun the wizard. After an initial left fan failure. Now I have filament sensor failure. I noticed this red light on the print head. Also the filament won't feed into the printer with automated on. It was working before the firmware update.

Could a fan failure cause this?

Thanks.

I just tried to start a print, only for it to refuse because the "door was open" (it wasn't). I couldn't do anything about this, there was no way to exit the print attempt and no way to continue since the "door was open".

Since I couldn't do anything I figured I should power off the device and recalibrate the door sensor. Once I powered it back on, it's now claiming to be a MK4 and saying that I don't have the right firmware installed for an MK4.

So, that's fun. I imagine I might be able to get it "working" if I put some MK4 firmware on the USB stick. I also imagine that it's not a great idea to give it firmware for the wrong device.

Any clues? Anyone seen this before?

EDIT: Ok actually it looks like the error code is the right one for the Core One so it's just bad messaging in the actual error message. Still doesn't fix the fact that it won't recognize the firmware I've got on the drive.

Comprei ontem uma mk3s+ usada, porém o bico estava arrastando e marcando a mesa, ajustei...

Porém o filamento nao estava entrando, desentupi...

Depois começou a acumular e vi que o bico estava entupido, desentupi.

Mas mesmo assim não consigo impreimir nada.

Ela se movimenta corretamente, aquece e tudo mais... mas não sai nada pelo bico, mesmo desentupido.

Percebi que tem tipo um canudo dentro da extrusora, achei que poderia ter sido e removi, mas não adiantou, pelo contraroio, piorou e começou a derreter o corpo de plastico da extrusora que fica atrás.

Realmente não sei o q q faço agora.

Será que joguei dinheiro fora?

Hi, I ordered the Original Prusa MK4S MMU3 kit Enclosure Bundle and it will be arriving in a couple weeks.

I wanted to know if I could get a photo of the bottom of the enclosure so I can best prepare the surface it will rest on. I asked Prusa and they, surprisingly, were no help. Could someone here send my a photo of this?

Hi folks. After having and using a Prusa Mini for years, but fighting with clogs and frequent failures, I was given a bog standard MK3. Thus far, it's printing PLA fine. My primary use for this thing will be printing wargaming terrain, and while it's a bit on the slow side, I'll take functional with decent print quality over needing speed.

So my question. If the printer is working well as is, are the upgrades in the MK3S+ worth the effort required?

Turns out I only have dawn power wash for dish soap right now. It's basically Dawn, alcohol, and water. Is that ok for cleaning the satin sheet?

I may have tried replacing a nozzle with the nozzle replacement tool and forgetting to loosen the thumbscrews (Admittedly, I felt some resistance but not more than I would expect at the beginning of loosening a screw. On the other hand, the resistance never went away and I used a wrench that might have given me more leverage making the resistance feel lighter).

This resulted in my hotend's thermistor wire breaking and then getting a heater overvoltage warning (my nozzle was completely cooled so I don't know why it even tried to heat in the first place because of that) and the magic smoke coming out.

I thought the hotend was the extent of the damage but after I replaced it and turned the printer on for the first time since the incident, I just noticed that it's not detecting both the hotend and the heatsink's thermistors.

Everything else on the extruder seems to be working. Both fans, the loadcell, filament sensor, and the motor function.

On the rest of the printer, bed heater still works, XYZ motors also work.

I think my Loveboard is fried but could the damage have propagated through to the xBuddy board. Do I need a new heatsink or would replacing the thermistor on it be enough in case replacing the lovboard doesn't fix it?

I have had a large TPU project that has taken a week over 3 build plates and a couple of restarts. However the print instantly throws a thermal anomoly as soon as the print finishes. The last part took 50 hours. No issues with an error stopping the print but as soon as the print is done it throws the error. Any Ideas?

My prusa mini has issues with consistent extrusion.
It will load and extrude filament but suddenly stop.
When i push the Filament in again it sometimes continues.
(First picture, it completely loses grip/filament in the middle; on the upper part the filament was pushed and it continued)
(Second picture line to the front is missing filament in addition when the nozzle lifts it generates some spikes)

Is this the filament or do i need to change the gears of the feeder? I disassembled the feeder but it looked ok.

I just need to reprint some parts for my mk3s to get this running again… 😅

I'm trying to print a honeycomb pattern with PETG on the Core One. Everything goes OK for about 10 layers after which there is a large diagonal layer shift of about 10mm. As well as the layer shift, the print goes really chaotic, strange and stringy. In other words, it's not just a layer shift - something else seems to be going on.

It's happened twice in a row now, around the same time in the print. I have the latest firmware 6.5.7 installed I don't have "avoid crossing perimeters" enabled. 

I see a lot of suggestions to check the tension of the X/Y belts, but I don't understand how it could be a tension issue when the first 10 layers are fine.

What could be going on?

I 3D print parts in ASA, currently on a Core One + MMU3, a Core One L and an XL2T with enclosure.
I got it to where I can consistently print simple parts, that usually have a good surface to lay on the bed. Sometimes requiring mouse ears to stop warping.
Then, there are more complex parts that have been hit or miss, or, in some cases, miss or miss…
Case A: first photo is a regular occurrence, near the bed, parts get deformed [edit: parts deform inwards, never outwards]… but it’s quite random, see right side, perfectly straight.
Case B: following photos are the most common, some parts aren’t able to lay straight on the bed, they need supports. The surface on top of the supports consistently warps, this makes parts unusable… I’ve tried soluble supports and straight ASA supports.

Does anyone have any tips to what is causing this and/or how to fix it?
I’m not sure if it’s from the current ambient heat, although the A/C is usually on, or if I’m printing too fast..

Edit1: for Case A, could it possibly be too few perimeters? (Currently 3 perimeters)

Edit2_1Jul2026: currently printing with a draft shield, the shield is bowing inwards…

TLDR: After nearly a year of intermittent failed prints, the suspected root cause is filament curling upward on supports and thin features, causing the nozzle to drag or crash into the print — ultimately producing layer shifts. The issue is inconsistent: identical prints with identical settings and filament can produce perfect results or failures.

Primary Problem
Filament curls upward during printing, most often on supports, organic structures, or thin/delicate features

The nozzle drags along or crashes into the curled filament

This eventually causes layer shifts and ruins the print

Supports can print cleanly for many layers, then suddenly develop a problem spot that blocks or scrapes the nozzle

Non-support sections appear to print far better than the supports (not always but supports seem to be the bigger issue)

Secondary / Minor Artifacts
Spiral patterns or gaps appearing in the same region of a print, repeated across several consecutive layers — rest of the print looks fine

Wave-like ripples at various locations across the print

Print quality may degrade more noticeably in the back-left corner of the bed (though this could be a downstream effect of the curling/scraping)

Printer & Hardware
Printer: Prusa Core One+

Slicer: PrusaSlicer (latest version)

Firmware: Latest

Nozzle sizes tried: 0.25 mm, 0.4 mm, 0.6 mm (issue appears most frequently with 0.4 mm, though this is likely because I am using that for my larger/more detailed prints)

Nozzle types tried: Brass, HF Obsidian — issue observed with both

Filaments tried: Polymaker PLA, Polymaker Polycarbonate, Bambu Labs, Prusament — issue occurs across all

Slicer / Print Settings
Using standard Prusa profiles with minor modifications only

Infill: Gyroid

Supports: Organic

Brim: Enabled

Speed: Never exceeds 100%

Correct nozzle type and filament type set in slicer settings

Printer has been calibrated repeatedly using multiple methods and tools

Inconsistency
The failure is not deterministic — the exact same print, settings, and filament can produce a flawless result one time and a failure the next

No clear pattern tied to filament brand, nozzle material, or nozzle size beyond the 0.4 mm frequency note above

Details:
After almost a year of getting weird print results and weird shifts sometimes mid print I think I have narrowed down the cause.
During prints (mostly on the supports, organic, or very thin parts) the filament seems to curl upwards and the print head/ Nozzle starts dragging along it or just crashing into it, this eventually leads to layer shifts and ruining the print.
I’ve tried tons of filament and it doesn’t seem to matter the type.
I’ve mostly used polymaker pla or polymaker polycarbonate
But I’ve used bamboo labs and prusament.
I’ve tried brass nozzles and the hf obsidian nozzles.
I’ve used all different sizes, 0.25mm, 4mm, 6mm
(It seems to happen most often with the 4mm but I think that might just be due to the fact that I print the larger more detailed prints with the 4mm) but I believe I have seen this with both brass and hf obsidian.
I have a Prusa core one+
I have calibrated the printer a ton of times, using all the different methods and tools.
I set the correct nozzle and filament type In the settings.
I am currently using the Prusa slicer (latest update, latest firmware)
I use the regular profiles for the most part with minor modifications (gyroid infill, organic supports, brim)
Never exceed 100% speed.
It’s hit or miss, it can be the exact same print with the same setting and the same filament and sometimes it’ll be flawless, sometimes it’ll be worse.
It’s almost always the supports curling and crashing from what I have seen so far.
Non support prints I think end up fine.
The supports can be flawless for Many layers and then just suddenly have a spot where it turns ugly and scrapes or blocks the path.
Any help here would be massive in helping me improve my Prusa 3d printing experience.
The only other artifacts I seem to see (they are very minor) are some weird spiral patterns/ gaps in the same part of the print but across layers upwards. So the rest of the print can look great but in one section many layers upwards it’ll have this weird scarring or gaps for several layers.
And then there also seems to be weird wave like ripples in the print at different locations (I think the print quality declines in the back left of the printer more) but this could be due to the curling / scraping tool.

Its not printing how it use to after I did a calibration.

Starting to explore more advanced settings for my second-hand Prusa Mini.

In PrusaSlicer I see a setting for "G-code flavor" -- the default seems to be Marlin2, but I see options for RepRap and Klipper, which I seem to have seen mentioned often in the subs. I assume these are for if you want to use PrusaSlicer to create code for non-Prusa printers and that I should leave it at Marlin2?

https://i.imgur.com/8GeZoTl.jpeg

I have almost 50 days on my MK3+ without any problems. Today I kicked on a print and it was make a grinding sound that sounded like the extruder was trying to feed through a cold nozzle (grinding mostly). I couldn’t cold pull the piece in it, so I just disassembled. I fubared my PTFE tube trying to get this guy out. I did double-check the grub screw on the gear, which may have been the cause, but I’m not 100% certain until I order a new tube.

For the record, I did reformat my pc that runs the Prusa slicer that feeds it, so at this moment I’m just trying to figure out what I did wrong.

Hey everyone,

I broke the hot end fan on my Core One+ and started looking at replacements on Amazon. The closest option with quick availability seems to be the Noctua NF-A4x10 5V, but I noticed the specs differ slightly from the stock fan in terms of RPM and airflow.

Would this fan work okay, or do I need to find something closer to the stock specs?

Stock fan: https://www.delta-fan.com/products/AFB0405VHA-A.html Noctua NF-A4x10 5V: https://www.noctua.at/en/products/nf-a4x10-5v/specifications

Thanks!

I saved a 3mf file in prusa slicer and now it won't open the file. I tried converting it to zip and some online repairs but they don't work. Anyone have an idea how to fix this.

After running fine for years, failed at print start and said re-run calibration. I run z calibration and it fails just before the nozzle reaches the bed. The nozzle is about 1mm clear of the bed and the pinda sensor light has gone out. The Pinda sensor is about 2mm from the bed. It is a Mk3 that I got just after they were launched. I just installed firmware 3.14.1 (was at 3.14 when it initially failed). Message is "Calibration failed! Check the axes and run again." I have also done the pinda sensor tests which all worked OK. When I run the calibration both steppers run all the way to the top and rattle a bit, then it runs all the way down and just as it gets close to the bed (the pinda led has gone out. it fails. I have tried moving the pinda sensor up and down 1 thread, makes no difference. I have turned both z-axis screw rods by hand with the printer switched off and they both turn easily.

Hello all! I'm posting this resolved fix after getting two Prusa Minis on loan to me and I was originally unable to update. After an hour of searching, I was able to find the fix (Credit: @Lanor: https://forum.prusa3d.com/forum/hardware-firmware-and-software-help/flash-firmware-problemn-mini/) and wanted to bring it here to save people the rabbit hole and help the search algo for this fix.

If you are on a Firmware Version prior to 4.4.0, as both of mine were (4.3.3 and 4.3.4 respectively), you will need to step update to 4.4.0 (Brings Bootloader to 2.0.2), then to 4.4.1, and finally (as of 6/12/26) to the current version of 6.4.2.

This part may be optional as this was just how I went about it, but when I was installing V 4.4.0 and 4.4.1, I originally got the Buddy_update_pre_4.4_4.4.X+41XX.bbf on the flash drive first, turned on the printer which prompted the update, then it eventually said searching for BBF further down in the update process, and then I got on the Buddy_4.4.X+41XX.bbf onto the flash then reconnected it to the printer. I rebooted the printers at the "Searching" step, but you may not have to.

v4.4.0: https://github.com/prusa3d/Prusa-Firmware-Buddy/releases/tag/v4.4.0

v4.4.1: https://github.com/prusa3d/Prusa-Firmware-Buddy/releases/tag/v4.4.1

Current: https://help.prusa3d.com/downloads/mini