Did extruder assembly self-destruct on 1st print!?!?
Let me start off by saying that I just recently purchased my Prusa i3 MK2S kit and so far I have been pretty disappointed. I purchased the i3 MK2S to replace my self-improved (heated printbed, upgraded PSU, upgraded bearings & rods, bed leveling, etc) Print-Rite DIY. The i3 MK2S was supposed to be a significant upgrade over my Print-Rite DIY.
Purchasing the kit version did turn out to be a long and tedious assembly process, but I knew this going into it and the assembly instructions are extremely clear and well documented. However, 1/3 the way into the assembly, I realized that my kit was missing an ENTIRE BAG of 3D printed parts that corresponded to an entire chapter even though a checklist was included in the kit saying all the parts were present. This makes me think that the checklist is provided as more of a “feel good” document rather than an actual QC process check. I had to wait another 5-days for the missing parts to arrive at my door (free of any charge).
I finally finished all the assembly last night. Powered on ok and completed the setup wizard and all calibration steps without any issues. Printed the Prusa logo from the provided SD card to verify that everything was working decently without any issues. Again, okay.
At this point, I decided to print my first “real” part. The part I was trying to print is more-or-less a solid block shape, roughly 175x65x100mm. Unfortunately, I currently do not have an SD card writer so I used PrusaControl to generate G-code and the Pronterface provided with the Prusa software suite (and documented in the handbook) to attempt to print this part via USB. Printing via USB is a process I am extremely familiar with as this is how I have done countless prints on my Print-Rite DIY so I didn’t think there would be any issues with this. I imported the G-code to Pronterface, checked the settings, made sure everything else looked good, and hit print. Estimated print time was going to be 8-10hrs (big part, 0.3mm, 70% infill [it needs to be a very strong part]). I watched the first 20 minutes or so to make sure everything looked ok, and then went to bed.
I woke up roughly 5-hours later to hear the i3 MK2S making a very loud, high pitched, tone. I run to check on the printer and found a huge blob of PLA (like 0.5kg! worth) stuck to and built up all around the extruder assembly. The LCD was reading a MAXTEMP alarm. I immediately powered off the power supply. Checking the Pronterface log, I see that at some point an “Error:0” was encountered. Pronterface also showed that the extruder temp had reached 738degC. Wait, what?!? Surely that’s not even possible! I started to try to clean off the blob (it’s 100% solid cooled PLA at this point) with the knife tip on my solder station. After about 1-hr of trying to clean off the blob and only getting about 15-20% cleaned off, I become extremely frustrated and decided stop cleaning to try to check to see if the extruder electronics were even functional anymore so that I don’t waste any additional time cleaning up the mess only to find out that everything was destroyed. I powered back up the PSU, and was still getting a MAXTEMP alarm. Reset button, same alarm. Reset button again, same alarm. When it does read a temperature, it’s over 200degC even though the extruder heater is off. Obviously, the thermistor is destroyed and I am getting erroneous readings. My question now is should I consider everything on the extruder assembly (extruder motor, hot end, heating element, PINDA sensor, fans, etc) ruined? I would prefer not to waste any more time (many hours) cleaning this mess up if everything is ruined. What should my next steps be? Pictures and video provided below.
Next big question, why did this even happen in the first place? How did the blob get so big? I have never seen anything even remotely similar to this type of problem on my (cheap) Print-Rite DIY. Failed prints, definitely. But usually a failed overnight print resulted in a stringy mess that was relatively easy to clean up. This though, is a completely different issue and much more serious (it ruined parts and was only the 1st print!).
Here is a video of the continuous MAXTEMP alarm:
Here are pictures:
Re: Did extruder assembly self-destruct on 1st print!?!?
Found this in the knowledge base: http://help.prusa3d.com/l/en/article/08OdUoqqdQ-extruder-blob
I can say for sure that 1st layer adhered. Guess is that it looks like about the 20th layer is where it broke off. This is a terrible way to "learn the hard way" that the PLA probably needs glue on the PEI film (I am used to printing on glass, and dont need anything else) Guess I will continue to clean up the mess the best I can. I will have to use my solder station (hot knife tip and hot air) to clean things up since my extruder thermistor is damaged preventing the hot end from heating.
Meanwhile I will recommission my Print-Rite as it doesnt have this problem and use it to print any replacement parts that break during cleanup.
Re: Did extruder assembly self-destruct on 1st print!?!?
This is a terrible way to "learn the hard way" that the PLA probably needs glue on the PEI film
Sad to see such a mess.
I take it to be very confident to make such a big print just after building the kit and printing just the prusa logo. No offence intended.
I made the experience that especially PLA sticks like hell to the PEI sheet with correct 1st layer calibration.
It sticks that hard that I have to take it from the bed before the bed cools down, after that it is nearly impossible to
remove the print without damage to the part or to the sheet.
Some even use some babypowder to reduce adhesion for bigger parts, as do I.
Regarding your big blob-creature... Could it be, that maybe someting in the nozzle-heatblock-heatsink-assembly was not properly tight
and the hot filament leaking where it should not?
Re: Did extruder assembly self-destruct on 1st print!?!?
It looks really scary.
I would also not recommend to start a big print and leave it over night without knowing the printer. All the good reviews regarding the printer seduce to think it's 100% reliable thing but it's still a 3D printer. There are so many things which might go wrong. It make sense to be around it at least for the first time once you get used to the printer and the filament you are using.
Regarding the PEI sheet and PLA I had the same experience. When I got/assembled the printer, the PLA was not sticking well. I assume it's because of the very smooth original surface of the sheet. It need to be slightly rough. After the original sheet broke after a year, I replaced it and it was a completely different story. Everything sticks very well PLA/ABS. I used a tool and slight force during assembly, so the surface was naturally fine sanded.
This is something I would recommend as well. Very light sanding helps to remove this absolutely new glossy surface. The first layer looks still awesome and stick well.
Often linked posts:
Going small with MMU2
Real Multi Material
My prints on Instagram
Re: Did extruder assembly self-destruct on 1st print!?!?
No offense taken, try, fail, and learn. Yes, I guess I was very confident that there wouldn't be any issues with printing a semi-large piece as I had printed much bigger pieces before on my P-R DIY. And yes, I suppose I was "seduced" by all the great reviews and ratings on the i3 MK2S. It is a big reason why I chose this model for my upgrade from the DIY. That said, in hindsight, I probably should have started smaller or printed these pieces on my DIY (I needed the pieces by this weekend) which I have more familiarity with.
I suppose the major difference between the i3 MK2S and my DIY in this regard is that the MK2S has a bunch of plastic around and very close to the hot end tip. The DIY doesnt have this, so there's not really anything for the hot PLA/ABS to adhere well to (since the DIY extruder is either aluminum or brass, no plastic). The MK2S has the fan shroud/diverter and PINDA mount, which I think gave the PLA something to adhere really well to. I suppose the learning curve is definitely different with the MK2S. Reference pic of DIY extruder below.
Re: Did extruder assembly self-destruct on 1st print!?!?
Good luck on removing the plastic. Take your time and it will be great to see if anything broke.
Often linked posts:
Going small with MMU2
Real Multi Material
My prints on Instagram
Re: Did extruder assembly self-destruct on 1st print!?!?
Well, I wasnt able to save everything. I now need to replace all the plastic pieces on the extruder, a new heater cartridge and thermistor (wires were too embedded in the blob to save). Looks like the fans and PINDA sensor is okay, but am ordering one just in case.
Re: Did extruder assembly self-destruct on 1st print!?!?
Wow. Yeah, I am new to printing. I built the MK2S kit as my first printer a week ago. It took about a week to it all dialed in. There are many parameters involved in getting to good adhesion. I just posted a long reply to a thread I started last week. I listed 10 things I learned just related to the bed adhesion using PLA. Now, it's fantastic.
Re: Did extruder assembly self-destruct on 1st print!?!?
Wow. That is a nice one! My tumor (as I called it) was not nearly as nice.
1) PLA sticks just fine to the bed if you do the first level adjustment correctly. You clearly did not.
2) You should not leave the printer un-attended for extended periods until you are sure it is dialed in. You clearly did.
Sorry.
To get the first layer dialed in, read this:
To get that tumor off - heat the hot end (if it functions great, if not use a heat gun) and CAREFULLY remove it with needlenose pliers.
The wires on the thermistor are thin, so don't yank or you will break them - easy to replace, but still.
Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage or loss. If you solve your problem, please post the solution…