Thermal problems printing PETG
My printer does a fine job printing PLA, but now that I am trying to print PETG, I am having thermal problems, including shutdowns with "Thermal Runaway" and "Preheat Error" messages.
The part I am printing is small and sits in the center of the bed, so when the part cooling fan is on, it also blows on the center of the bed, directly above the bed thermistor. A larger part might not trigger this, or I suppose I could move the part away from the thermistor, but this wouldn't keep the bed any hotter.
I'm using completely stock print profiles in Slic3r Prusa Edition; "Optimal" 0.15 mm layer height, Prusa PETG, and i3 Mk2 with Z-hop. The object is a drill bit handle, mostly a tall cylinder about 2 cm in diameter. I can provide the model (obtained from Thingiverse) if that would help.
Is the problem that my printer is simply unable to generate enough heat to keep the bed hot while the part cooling fan is blowing on it? It seems that it's possible to tweak the output voltage of the power supply, but I'm hesitant to poke around mains voltage unless I have to. I've checked the power and heater connections on my board and none seem to be loose. So how do I get PETG to print?
Re: Thermal problems printing PETG
Is the part cooling fan running at 100% all the time? It is a pretty powerful and efficient fan and maybe trying to lower it would help, especially when printing such a small surface area part. I run the fan at a maximum of only 30-40% when printing PETG.
On a side note, I print with PETG more than any other material. I run at much lower temperatures for both the extruder (230) and bed (55) than the stock supplied Prusa PETG settings. In fact I print at much lower temps than Prusa stock settings for all materials I use (PLA and TPU and nylon). I found my results were much more consistent and quite frankly better in every way at lower temps for every material. You might want to try lowering your temps and see what happens.
Re: Thermal problems printing PETG
Have you checked that the bed heat thermistor havent gone loose?
http://shop.prusa3d.com/forum/-f0/thermistor-came-loose--t4387.html
Also, i had the Preheat Error trying to heat to ABS values.
Support made me reflash 3.0.10 and that went away.
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Gert
Re: Thermal problems printing PETG
Have you checked that the bed heat thermistor havent gone loose?
http://shop.prusa3d.com/forum/-f0/thermistor-came-loose--t4387.html
Also, i had the Preheat Error trying to heat to ABS values.
Support made me reflash 3.0.10 and that went away.
The printer is doing a fine job printing PLA right now, so I don't think that can be it.
Re: Thermal problems printing PETG
I had this problem to with PETG. It's usually the bed that can't keep up. I lowered bed temp to 60 I think and it does fine. Just remember to wipe with windex instead of alcohol to clean bed before PETG.
Is your printer near a window or draft prone place? I think that might be contributing to my issues. May evenetually try an enclosure but as of now the lower bed temp works fine and prints still well.
Re: Thermal problems printing PETG
This cooling problem might also mean bed damage around inner heating circle, that is above thermistor. It heats from the sides first but once the fan kicks in, that area is not heated and goes way cooler. Got it myself with damages.
Re: Thermal problems printing PETG
Hi all,
I have exactly the same problem. I am also in contact with the support and they send me a new bed first which did not solve the problem. Yesterday I got a new RAMBO board but that also did not solve the problem. I made a ton of tests on my own and with the help of the excellent support. But at the moment it look like that the bed is simply not powerful enough to keep the temperature at such an high level.
I will let you know what the results are when we finished.
br,
Bastian
Re: Thermal problems printing PETG
I have NO experience with this, so take this as just a reference to what other folks have seen on this forum.
There is a potentiometer on the RAMBO board that controls the voltage to the heat bed. If tis is set too low, it can provide enough power to keep things okay at 60deg for PLA, but even full on can't keep up with hotter bed temperatures. People on this forum have turned the potentiometer a SMALL amount to provide a bit more voltage, and fixed this issue, but don't over do it. Best to measure the voltage and keep it in a safe range. Search for other threads on this topic.
My RAMBO seems to have come from the factory set fine for the PEG I have printed, but this is an adjustment that might be of value for you.
Redo the Bed PID calibration after adjustment to prevent oscillations.
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…
Re: Thermal problems printing PETG
Hi Aaron,
sorry for my late answer. I was on vacation the last few days.
Thank you very much for your suggestion. But I can not find any potentiometer on the RAMBO. Is it possible that it is in the power supply? [EDIT: It is on the power supply (Found it here in the forum). But I will first contact the support and see what they say]
I will discuss this also with the support.
I measured the power that arrives at the head bed when it is unter full load. And the multimeter says 11.55V. Can someone confirm that?
br,
Bastian
Re: Thermal problems printing PETG
Sorry, your are correct, the pot is on the PSU.
This thread:
http://shop.prusa3d.com/forum/original-prusa-i3-mk2-multimaterial-f26/bed-thermal-runaway-t4592.html#p33982
Had results setting it to 12.5V. Again, I have not done this, just reporting what others have done/seen. Check the above thread for details.
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…
Re: Thermal problems printing PETG
My clone bed is just the same. I think that some (perhaps all) beds are a little bit marginal in power at the high temperatures and when there's a fan blowing they can't keep up.
If I'm printing a small part I move it away from where the thermistor is. With a large part it doesn't really cause a problem.
Re: Thermal problems printing PETG
Hi all,
I was able to get around the problem. I invetigated the problem with a thermal imaging camera. The part cooling fan in this specific print was blowing directly on the part of the bed where the thermistor is located. I moved the part slightly to the back of the bed. After the change the print was flawlessly printed. The thermal images and videos of the printer are really interesting. You can see that the printbed is cooled down only on one specific spot.
Thanks for all your help.
Bastian