RE: MK3S part melted
Chiming in, 20 hours of printing, having the sagzilla. Extruder was printed with Prusa's provided PETG. Printer NOT enclosed during the print at that time, AND not turned off after the print for hours.
To all here who are trying to say it's user error, you are wrong. Supposedly there is a revision in the works at PR, but it's "low priority."
RE: MK3S part melted
My extruder is stock Mk3 - and I am quite happy with it. Optical filament sensor? Not so much.
That said, parts melting in and around the hot end is related to what I call silliness. Hot end fan turned off or not working, heated enclosures with ambient temps 50c plus, etc.; generally problems that are self generated shoot-yourself in the foot things.
As an aside: Guy - have you measured the air temperature coming off the heat sink when the nozzle is running at 290c ?? Specifically, temp rise over ambient near the bottom fins?
RE: MK3S part melted
My extruder is stock Mk3 - and I am quite happy with it. Optical filament sensor? Not so much.
My optical sensor mostly worked so I am not happy that it's jam detection is lost. Before my MMU started working I was going to do the Butterworth upgrade that changed to monitoring a bearing rather than the filament itself and go back to the MK3 firmware. I have all the parts ready to go back to that, but I don't particularly want to piss of the MMU now that I have it working 😆
That said, parts melting in and around the hot end is related to what I call silliness. Hot end fan turned off or not working, heated enclosures with ambient temps 50c plus, etc.; generally problems that are self generated shoot-yourself in the foot things.
Not sure I understand here. There appear to be plenty of us that are doing nothing "silly" and are having this issue.
40ish hours of PLA printing not in an enclosure, fully working fans, and in a cool (65-70 degrees) room and my "fin" had already sagged. Nothing aggressive. No weird heat issues (unless the 3.7.0 firmware did something funky, but it seems to be working fine from what I've seen).
The (Prusa printed in my case) part failing with such little use is what I would call silliness...
RE: MK3S part melted
My extruder is stock Mk3 - and I am quite happy with it. Optical filament sensor? Not so much.
That said, parts melting in and around the hot end is related to what I call silliness. Hot end fan turned off or not working, heated enclosures with ambient temps 50c plus, etc.; generally problems that are self generated shoot-yourself in the foot things.
Know what's silly Tim? You claiming that me using PRUSA PET profile in Prusa's PrusaSlicer on Prusa's Prusa MK3S/MMU2S.... with the S..... as in ssssnake... a sssneaky ssssnake..... is "silly."
Know what is also silly? As a MK3 Original user, criticizing all of the MK3S users who are having problem, which incidentally, there's quite a few out there with the melting issue on Facebook, posting pictures, along with on here posting pictures.
RE: MK3S part melted
Gnat - I'm on my original ABS MK3 extruder ... so have nothing to compare. But most of the reports I've read people having the issue are using enclosures or printing high temps near 300c or both.
What you describe - a Prusa printed extruder part sagging under normal 25c ambient use (if your hot end fan is running and you routinely clean dust off it and the heat sink) -- well, that isn't self induced silliness.
RE: MK3S part melted
Gnat - I'm on my original ABS MK3 extruder ... so have nothing to compare. But most of the reports I've read people having the issue are using enclosures or printing high temps near 300c or both.
What you describe - a Prusa printed extruder part sagging under normal 25c ambient use (if your hot end fan is running and you routinely clean dust off it and the heat sink) -- well, that isn't self induced silliness.
The original MK3 extruder wasn't ABS. Only the fan shroud. It's PET unless they did something special for you specifically...
RE: MK3S part melted
My extruder is stock Mk3
Exactly. The MK3's R3 extruder design didn't exhibit these sag issues as much as the R4. My R3 (PETG) only got a little discoloration of the fin before I upgraded to a different extruder.
We keep reading about the R4 sagging without users doing stupid or high temp stuff.
Something is awry with the MK3S's R4 thermal design around the hot find and PINDA holder.
have you measured the air temperature coming off the heat sink when the nozzle is running at 290c
Have not instrumented the fin, but remember I'm running a Bear derived BNBSX which has a completely different design in that region. It survives sustained 273 degrees nozzle printing Polycarb inside a 40C enclosure for days without a problem. That's just with PETG for the extruder and hot fins! I haven'g gotten around to installing my polycarb fins and extruder body yet.
RE: MK3S part melted
Lol... I dunno about you, but I don't print PETG at 290C. 😛
RE: MK3S part melted
My extruder is stock Mk3
Exactly. The MK3's R3 extruder design didn't exhibit these sag issues as much as the R4. My R3 (PETG) only got a little discoloration of the fin before I upgraded to a different extruder.
We keep reading about the R4 sagging without users doing stupid or high temp stuff.
Something is awry with the MK3S's R4 thermal design around the hot find and PINDA holder.
have you measured the air temperature coming off the heat sink when the nozzle is running at 290c
Have not instrumented the fin, but remember I'm running a Bear derived BNBSX which has a completely different design in that region. It survives sustained 273 degrees nozzle printing Polycarb inside a 40C enclosure for days without a problem. That's just with PETG for the extruder and hot fins! I haven'g gotten around to installing my polycarb fins and extruder body yet.
I'd be willing to pay for a MK3s/MMU2S compatible extruder upgrade in black polycarb... lol... if anyone has em. LOL
RE: MK3S part melted
My extruder is stock Mk3
Exactly. The MK3's R3 extruder design didn't exhibit these sag issues as much as the R4. My R3 (PETG) only got a little discoloration of the fin before I upgraded to a different extruder.
We keep reading about the R4 sagging without users doing stupid or high temp stuff.
Something is awry with the MK3S's R4 thermal design around the hot find and PINDA holder.
have you measured the air temperature coming off the heat sink when the nozzle is running at 290c
Have not instrumented the fin, but remember I'm running a Bear derived BNBSX which has a completely different design in that region. It survives sustained 273 degrees nozzle printing Polycarb inside a 40C enclosure for days without a problem. That's just with PETG for the extruder and hot fins! I haven'g gotten around to installing my polycarb fins and extruder body yet.
I'd be willing to pay for a MK3s/MMU2S compatible extruder upgrade in black polycarb... lol... if anyone has em. LOL
There was a guy on Etsy the fan shroud upgrade in polycarbonate. Maybe he does more.
RE: MK3S part melted
I know who that is actually, and I won't order from him after how he responded on social media. A very uncool situation, but I'm not going to trash anyone here.
RE: MK3S part melted
Just measured my MK3 at 25c ambient and 285c nozzle: air temp directly behind heatsink (low flow region due to PINDA proximity): 51.9c highest reading after 30 minute soak. It is impractical to accurately measure the plastic temp with the tools I have, but if the top side is exposed to 50c air flow, it seems unlikely it will melt into a ball like some of the photos show. Distort, warp, bend? Probably; the lower plastic surface below the fin area is getting the full radiant blast from the heater block a cm away.
I'm only trying to add information, not argue one way or the other.
RE: MK3S part melted
I'd be willing to pay for a MK3s/MMU2S compatible extruder upgrade in black polycarb... lol... if anyone has em. LOL
Polycarb IS in reach of you MK3S. Polymax Polycarb prints very nicely and supports clean off it better than PETG. Results are about 10% lighter, stiffer and of course more heat resistant.
My point is our printers SHOULD be able to do it as delivered, but we have to make some tweaks to make it happen. Here is the BNBSX extruder body, including bridges, printed in PolyMax polycarb. I see a couple zits from having the spool out 4 days, but overall it is nice. Printed on BNBSX extruder and 0.9 motors on
MK3S printer.
Because it is off topic, I'll put details of using Polymax in separate thread.
RE: MK3S part melted
Just measured my MK3 at 25c ambient and 285c nozzle: air temp directly behind heatsink (low flow region due to PINDA proximity): 51.9c highest reading after 30 minute soak. It is impractical to accurately measure the plastic temp with the tools I have, but if the top side is exposed to 50c air flow, it seems unlikely it will melt into a ball like some of the photos show. Distort, warp, bend? Probably; the lower plastic surface below the fin area is getting the full radiant blast from the heater block a cm away.
I'm only trying to add information, not argue one way or the other.
You have a MK3. I have a MK3S. You're trying to say it doesn't happen. Photos say it did. Sounds like an argument to me. The best and only test to properly check this, is to get meter with a thermistor/thermocouple, attach that to the fins that are melting, and run a full print, logging the temperature information.
Analogy: With hot air rework soldering for SMD components, how far the air is, AND for how long will determine how the solder melts, and how the items set up in place. Too much air, heat, and being too close, and you start blowing components off the mainboard....
If I can find mine, I'll try to get a good measurement as to how much heat is really getting to those fins. I have it in a tool box somewhere...
RE: MK3S part melted
Chase - don't put words in my mouth. I am fully capable of finding ways to put my foot in it. I did NOT say it can't happen. I even said there are photos of the melted pieces. I did say I am dubious as to root cause being so simple.
It's a data point: one that suggests to me in normal ambient conditions there doesn't appear to be enough heat to melt plastic at the bottom heat sink fin. MK3 vs MK3s - there are mechanical differences, but are they enough to substantially change airflow? Enough to collect more radiant heat? Good questions I can't answer.
I also doubt you can instrument the plastic in a meaningful way. IR, maybe. In lieu of an IR camera, determine the emissivity of the plastic and calculate the radiant heat coming of the heater block and nozzle that impinges on the part. Take the thermal conductivity and do the math to find the conducted and convective losses, especially from the top fan cooled surface... and find the net sum heat and resulting temperature.
Sorry - too many years engineering traceable measurement systems - so I dweeb out once in a while.
Hopefully, you'll find something that causes this.
RE: MK3S part melted
I have tried to point Prusa Research to this forum thread by email. I would really appreciate an official answer from them.
Some information on my printer and how I use it:
- Ordered an MK3 kit 2018, upgraded to the MK3S this year using the official MK3S upgrade kit. The MK3S parts were self printed using the provided PETG and the official gcodes on the website.
- The only addition to it is the Raspberry PI Zero W, which was added as shown on the Prusa website.
- The printer is located in the basement of our house at normal room temperature.
- The printer is used about once a week for a couple of hours, the longest prints I did was ~10 hours.
- Materials used include PLA, PETG and ABS.
- When printing ABS, I put the printer into a "photo tent" enclosure. The longest ABS prints were ~6 hours.
- I used Slic3er PE and PrusaSlicer for preparing the gcodes, I never used anything else than the factory provided settings.
I really cannot see anything silly with how I used the printer. I don't consider myself a power user, but still the hot fins melted away. Maybe I also had the PINDA holder sag, but probably I didn't notice.
I have now printed the version provided by @guy-k2 (Thanks, I really appreciate it!) and I hope to find some time to apply the changes to my printer in the next couple of days. But as I understand it this is not really a fix but more of a workaround that enables to replace melted hot fins without taking apart the whole extruder in future. The BNBSX would be an interesting option, but I'd like to stick to the original Prusa printer for convenience.
RE: MK3S part melted
I have tried to point Prusa Research to this forum thread by email
We on the forum hear you, but it's pretty unlikely you will ever see a official response from Prusa in a forum thread. That's the way most manufacturers treat their forums. When a company rep gets detected online, they invariably get clobbered by less than positive feedback. The really strong ones last a couple months. Most quickly flee. At least that is my several decades experience with online forums has been.
They do respond via chat, but you probably won't get a high enough level person through that channel.
Often , it feels like forum members have to look out for each other - the company usually won't directly intervene.
MK3S x-carriage?
While we are at it... If are someone who has had a fin melt or PINDA droop, could you please take a look at the x-carriage for me?
I'm interested in the bottom portion of the x-carriage nearest the heater block. A few weeks ago, I adjusted the BNB Universal X-carriage to keep its bottom edge sufficiently away from the heater block. I'm wondering how the Prusa MK3S x-carriage is doing. (I don't have a Prusa x-carriage in operation here)
RE: MK3S part melted
@guy-k2 There you go! i was about to throw it away.
there is some melty stuff going on at the bottom but it looks very superficial. Keep in mind that the hottest temp i used is 255C at the extruder and 110C at the bed, all in a 40-45C enclosure. I have a hunch that this whole issue might be related with a combination of the radiant heat from the bed and the hotend, but some people reported it even with pla printing, so i might be out of luck there.
While we are here i'll also link a couple of photos of the melted parts. Unfortunately the PINDA mount did not survive disassembly, i guess the heat rendered it brittle.
I ended up printing out the whole assembly in ABS+ for the thermal resistance, the Butterworth variant (i really, really wanted the corrected filament path, but the BNBSX require a little more time and material investment, and i needed a quick replacement.), let's hope it keeps it's integrity for now.
@oliver-h16 You WILL notice if the PINDA mount start sagging, as you would have to re-adjust the live Z every single print, and the tilted probe will give some weird responses, such as taking multiple tries and pauses while doing the mesh leveling.
Edit: Jesus, the aspect ratio in the images has gone it's own way.