Can't print PLA in an enclosure
So I have figured out that at least with my MK3 it is not possible to print PLA in an enclosure (unless you have a large amount of air flow.) I am using a Lack enclosure with 120mm case fan. The enclosure gets warm inside, but not overly hot( remember im only printing PLA) and couple that with the high operating temps of the extruder motor and within 30 mins of printer the bondtech gears are so hot the PLA softens enough to jam every print. The extruder motor is so hot it will burn you, as well as the gears. This is printing PLA at a low temp. I find the operating temperature of the extruder motor to be unacceptable. As the prints I am doing do not even have many retraction moves, I can imaging that if I printed something with many retractions this would occur even outside of the enclosure. I think Prusa needs to find a way to cool this area, or create a space or insulation between extruder motor and the housing.
In the meantime, does anyone have any ideas to solve this issue, or have experienced the same? I have searched other threads, and found some that I will try. Right now, I just have to print without my enclosure. If anyone is wondering why I print PLA in an enclosure, my printer is in my room running with me next to it, so I use the enclosure to help with particulates emitted from the printer.
Thanks for any ideas you may have!
Re: Can't print PLA in an enclosure
Does your filament sensor work? A failed sensor can dramatically overheat - I'm suggesting that the motor might not be the source of your woes.
Re: Can't print PLA in an enclosure
I've also done an enclosure with "ikea hacks" (with the stuva frame) for my prusa MK3. I don't use any fan for air flow. i just put a little thermometer to measure the temperature inside. While printing PLA (Prusa PLA or ColorFabb PLA) (215°C/60°C) i've no problem to print it. The enclosure inside reach 30°C (+/-5°C) and the extruder works fine. What brand of PLA are you using ? And what accuracy 0.1 mm , 0.2mm ?
Thibaut
MK2S and MK3 owner
Re: Can't print PLA in an enclosure
Thanks guys! I might have a bad stepper. I am fairly confident it is not the filament sensor as it hasnt felt like the source of heat. But I will try to disconnect it altogether just to be sure. My ambient temp is probably higher than most, around 76-78f(25c). It happens to any type of PLA, from good brands. I ordered a temp gun, should be coming today so I will probably post a pic of how hot the motor and gears get, and try to get a reading of how hot it is in the enclosure itself, to me it doesnt feel like more than a few degrees hotter than ambient.
Re: Can't print PLA in an enclosure
I too have a lack enclosure and problems with printing PLA in it.
This is normal.
Place a thermometer inside the enclosure, and when the air temp gets above 35 degrees the hotend will jam.
That's because the hotend fan cools down the hotend with warm air.
The stepper motor will warm up a lot more if you have a model with a lot of retractions or a lot of z-hops.
This warmth will transfer over the hobbed gear onto the filament, and cause jams.
Less power to the motor via M907 Exxx (250-600 range) will cause it to skip steps, more power and it will grind through the filament.
The Prusa Extruder steppers get up to 70 degrees hot under normal conditions. PLA gets gooey at 55-60 degrees.
It's only with good airflow that the extruder has to work less and stays cooler.
There's nothing you can do about it.
Only a good airflow inside the case works, 2x fans in, 1x fan out. (intake is always double the outtake, or it will create air stalls) Or leave the door open.
Alternatively, print only with PETG with the door closed, PETG has no problems with heat.
Re: Can't print PLA in an enclosure
I too have a lack enclosure and problems with printing PLA in it.
This is normal.
Place a thermometer inside the enclosure, and when the air temp gets above 35 degrees the hotend will jam.
That's because the hotend fan cools down the hotend with warm air.
The stepper motor will warm up a lot more if you have a model with a lot of retractions or a lot of z-hops.
This warmth will transfer over the hobbed gear onto the filament, and cause jams.
Less power to the motor via M907 Exxx (250-600 range) will cause it to skip steps, more power and it will grind through the filament.
The Prusa Extruder steppers get up to 70 degrees hot under normal conditions. PLA gets gooey at 55-60 degrees.
It's only with good airflow that the extruder has to work less and stays cooler.
There's nothing you can do about it.
Only a good airflow inside the case works, 2x fans in, 1x fan out. (intake is always double the outtake, or it will create air stalls) Or leave the door open.
Alternatively, print only with PETG with the door closed, PETG has no problems with heat.
Thanks for the input! I agree that my best course of action is more active cooling. I can't print PETG because like I said, I am in the same room and PETG fumes are not great. PLA particles are at least inert, although breathing any UFPs is not great. I have my fan pulling through a HEPA (which technically doesnt filter UFPs so I can remove that for more flow. I am also thinking of mods to keep the extruder motor cool, such as heatsinks on the motor or a fan design to blow air through the little viewing holes on the side of the x carriage. (Someone already designed one, but I think it will mess with homing.)
I know the mk2 extruder motor runs upwards of 20c cooler, so I guess it might not be an issue for that model.
Re: Can't print PLA in an enclosure
the Mk2 prusa has a smaller diameter hobbed wheel, which means more steps per milimeter and therefore less effort to move the filament any given distance, at the same speed
it's like having a lower gear...
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
Re: Can't print PLA in an enclosure
I am also thinking of mods to keep the extruder motor cool, such as heatsinks on the motor or a fan design to blow air through the little viewing holes on the side of the x carriage. (Someone already designed one, but I think it will mess with homing.)
I know the mk2 extruder motor runs upwards of 20c cooler, so I guess it might not be an issue for that model.
I also have a heatsink on my extruder fan, which helps but not a lot. 1-2 degrees perhaps. Mounted a fan to the heatsink, but the motor was still hot.
Mounted the fan to the side of the Nema motor, then the motor got cool.
Did help a bit with the PLA jams, but never got rid of them entirely, because the jams from the warm hotend heatsink are still there. Many PTFE tubes were ruined until i modded the enclosure further with more air intake.
Take a incense candle and mount it inside the enclosure, then test you air flow with it.
My smoke did not go outside, because the fan stalled the air in front of the HEPA filter.
Re: Can't print PLA in an enclosure
I recently had problems getting a large thin object to print without warping. I wound up adding a couple brims to the model and then covering my open enclosure with a blanket to keep the temps up. After a 30hr print in PLA, my piece finally came out with no warping. Elevated ambient temps didn’t have any adverse affects on my printer at all.
Re: Can't print PLA in an enclosure
I recently had problems getting a large thin object to print without warping. I wound up adding a couple brims to the model and then covering my open enclosure with a blanket to keep the temps up. After a 30hr print in PLA, my piece finally came out with no warping. Elevated ambient temps didn’t have any adverse affects on my printer at all.
Thats is surprising, mine would jame within an hour if I did that. Thanks for the insight everyone. I did some temp readings and my extruder motor pegs around 55c, with the gears at 38-40c. This is with the enclosure OPEN. It is no wonder it clogs with only a few degrees more, as just running it normally outside of the enclosure it is borderline too hot for PLA. This is a little disappointing for me, but I ordered some heatsinks to try, and will add a fan down the road. Aside from that , I will be increasing airflow using some of devilhunters recommendations so that I can hopefully keep using the enclosure.
What worries me is that my prints dont even have high retraction. I don't even want to print something like the wireframe skull(found on thingiverse) as I feel like the PLA will melt due to all the retraction moves. This is a bit of an oversight on Prusa's part. The temp of the motor and gears are right at the limit for PLA, and as such will cause problems in certain scenarios where it is not a problem on other machines. My crappy Anet A8 is cool as a cumcumber( I know, its not the same) but still sucks that this wasnt considered at this price point.
Once again, thanks everyone!
Re: Can't print PLA in an enclosure
I took some temp readings tonight just as mine finished a 24hr petg print for comparison.
Top of frame (ambient): 26c
Extruder motor: 49c
Extruder gears: 45c