Prusa MK4 with Hardened Steel Nozzle 0.4mm / 3DXTECH CF-ASA and CF-PETG

My fist 3d Printer was the Mini Plus and it was a good intro to the craft. I was excited to upgrade to something that could supposedly handle the engineering materials I really wanted to print. I'll never buy another Prusa product again. When I needed it most, at a crucial time when I was getting my start up small business going, the MK4 has failed me. It has taken away so much time and effort and motivation. I will curse the name of Prusa until I die.

Early on I had the ball of death and I discovered it happens if you don't clean the nozzle before your print starts, especially if you print filament that oozes like Petg.  If you leave buildup on the nozzle and don't clean it before the print the nozzle will pick up the bed incorrectly due to the buildup.

If you make sure the bed and nozzle are clean before the print you shouldn't have issues.  I clean the nozzle and bed before every print and the 1st layer is always perfect, and the .9 stepper motors make beautiful prints. 

Posted by: @thejiral

If we want to focus on problem solving rather than other things what you have here is substantial layer shifts. This should only happen if there is some underlying serious issue with your machine. A very common culprit is a loose grub screw in the belt gears. I would check all of those and re-tighten all of them while at it. 

Another thing to check for is if the machine triggers crash detection. This can happen either because you have adhesion issues and the nozzle is indeed crashing into the part or it can be falsely triggered crash detection if some bearings have a bit too much friction. At least that is valid for the Mk3. The Mk4 also has this kind of crash detection, doesn't it? Anyhow, if it does, deactivate it. I found it causes more troubles than it does good. 

Last but not least. First layer adhesion. The blob of doom you had later on as well is something you can get with any printer if you have insufficient 1st layer adhesion. Usually that is because the print bed is not clean enough (fat residues from touching it with bare hands). There are tons of threads on that aspect. If you want to be basically 100% safe against blob of dooms, simply revisit your printer after the first few layers. It basically only happens if your adhesion is so poor that the object detaches already in the first few layers. If the object detaches fully later, you get a relatively harmless spaghetti monster instead. 

If the thermistor error accured after cleaning up a blob of doom, it is very likely that the undoing of that blob damaged the thermistor wires, which can happen very easily if molten plastic attaches to them. 

Posted by: @jeffl

Why does my Prusa MK4 suck so bad? I cant even print the same print without chaos. I got one good print out of 3 tries. the first try (middle print) was using fw_4_7_2_MK4, so then I changed to MK4_MK3.9_firmware_5.1.0-alpha2 and got a good print. I then I tried to print it again, bad print. I use PrusaSlicer 2.6.1+win64-202309060711

WTF!!!!!?????!!!!

 

I yield to your superior knowledge on the subject and will heretofore have more respect for the bedslinger platform.

Also, I apologize to everyone for hijacking this thread and taking up mind-space on something so banal.  My only defense is that I started out talking about something close to on-topic: the layer-shifting, as was shown in OP's pics.  My following opinions as to cause, primarily centered around bedsling v not-bedsling platforms, threw me down the slippery slope of off-topic-ness.  Lesson learned.  I continue to have layer-shift issues, so I'll create a new thread and avoid ignorantly positing judgements on the MK4 platform.

Is Bambulab incompetent or did it for cost cutting purposes build an inferior machine with the A1 Mini? I would say no to those questions. You wouldn't?

really, the belts required for a corex-y machine are not much longer and not much more complex.  Look at tons of industrial machines which are much more complex and operate 24/7.  Our very simple core-xy printing machines are not very complex in comparison.  Is a bedslinger more simple?  sure, but you're talking about simple differences in construction with a very big difference in performance.  That you can predict the mass you're moving about is so much more valuable than decreasing belt length by some small amount.  I appreciate all the thought you've put into this, but you're missing the forest for the trees.  Bedslingers are fundamentally flawed.  It's only by controlling a defined mass that you can really have a high-speed and well-controlled nozzle.  Have the 3d-printer manufacturers done a good job with this?  That's debatable, but one thing is clear:  only the CoreXY platforms will be successful over time in high-performance, high-speed and high-accuracy solutions.  Bedslingers were a platform of necessity wrt cost, but they can't possibly succeed in all the above areas.

Learn how to ensure good bed adhesion, especially how to clean the bed and how to keep it clean.

I have never seen a report of a blob of doom to date that was not caused by a very early bed adhesion failure.

This is the case for any printer btw, no matter if  Prusa, Bambulab or Ender. CoreXY or CorXZ.