Problem with brittle prints and clogging
Hello all,
I've had my MK3S for many years now and its been a workhorse with very few issues. However since last year I'm having more failed prints and issues than anything else. My two main problems are:
- Extremely brittle prints with very poor layer adhesion. Does not matter if I print with PLA, PETG or ASA. I can snap my prints along the layerlines with my hands.
- Failed prints due to clogging or supports failing. I get very frequent cloggs and it tends to happen at around the same Z-height regardless of STL.
Since a few years I moved to a new house and I got a dedicated 3D printer room in my basement which is great. I had no problems in the beginning, but above problems have become worse with times. The moisture levels are quite high in the basement during summer so I was afraid that it has spoiled my filament. However I tried to dry my fillament for 5 hour in my convention oven and it did not help at all.
Yesterday I took apart the entire printer head assembly but could not find any issues.
I've noticed that I'm getting a lot of thermal anomaly warnings lately. I've re-calibrated the thermal model, but it is still happening.
I'm starting to think that I might have a faulty thermistor in the hot end. If the temperatures are lower than the thermistor is reading it might explain the poor layer adhesion and the clogging.
My questions are:
- How can I evaluate if my thermistor is accuare?
- What else should I look into except exchanging the thermistor?
Thank you for any help!
RE:
5 hours drying might not be enough if your filament is very wet. Also try to have sufficiently high temperature in the oven (depends on the filament type of course). Thermal Anomaly stuff seems to be also caused by newer firmwares, maybe you should try downgrading firmware to a time where you had no such problems (in case you have a newer firmware). Just to see if it makes any difference.
To rule out the moisture you could also buy some new filament, maybe dry it after unpacking too and imediately test print. If it behaves the same, it is probably not (the only) problem you have.
Before changing the thermistor I would check one or two filaments by printing a temperature tower. It does sound like your temperature settings are too low for some reason. With a temperature tower you can at least see if your range makes sense and also test at which set temperature filament starts to clogg. Try to dry the filament very thoroughly before doing that, maybe 12h or so. Store in a dry box afterards preferably. If you have data from previous temperature towers that would help to check if something has shifted.
Brittleness also can be caused by low ambient temperature, if it is in a basement that might be also a factor. This is especially the case for ASA which will have very poor layer adhesion without enclosure and even with enclosure it might be worse if the room is very cold as also the enclosure temp will be lowered by that.
Mk3s MMU2s, Voron 0.1, Voron 2.4
RE: Problem with brittle prints and clogging
Thank you for the quick reply!
I tried to dry my PLA for 5 hours @ 45°C. Had a multi-meter monitor the temperature and it was surprisingly accurate in the oven. But I guess it might not be enough. I have a new spool still sealed that I will open and try tonight.
I've never printed a temp tower before, but I'll try to find a good one and see. Any recommendations? I'll do the tower with the new filament to have no effect from moisture.
I have a enclosure that I print my ASA in that is made from 16 mm MDF that I think is reasonably isolating. I don't think the ambient temp is the issue. I've also brought the printer out of the basement to do a couple of prints and I'm still running in to the same issue.
I'll try to post the temp tower results tomorrow!
RE: Problem with brittle prints and clogging
Ambient temperature is always an issue with ASA, unless your ambient temperature is north of 60°C, better 70°C. 😉
Those are by themselves already very unhealthy ambient temperatures for a stock Mk3 with PETG parts. Below that every °C will make layer adhesion worse and part cooling settings can have a big impact on layer adhesion too.
Don't get me wrong. One can print perfectly functional parts from ASA even at much lower enclosure temperatures, like 40°C or so but the lower you go the worse layer adhesion will be and the lower (preferably 0%) you'd want the part cooling to be. But that is a bit besides the point as you do seem to have the issue not just with ASA.
Regarding temp tower, no, I don't have a good one at hand. I print them rather infrequent myself. You need to have some custom g-code for the temperature jumps, some 3mf files out there might come with that already. I'd have to check myself again.
Mk3s MMU2s, Voron 0.1, Voron 2.4