Under-extrusion and TMC drive overtemp
Hello everyone,
I am currently printing many part in ASA so I put my prusa I3MK3S+ in an enclosure.
The enclosure have some vents and I install carbon active sheet on these to protect my self from fumes.
Due to maybe to well isolated enclosure I had a TMC drive overtemp issue. I solved that by installing a fan in the outside of the enclosure and printed a fan shroud in order to blow the fresh air directly on the main board. Since that the main board temp never exceed 40°C.
Since I had the TMC drive overtemp I have a huge issue with under extrusion.
First thing I have done is to clean entirely the extruder and put a bit of grease on the gear and the issue was not resolved.
I install heatsink on the body of the extruder stepper and nothing changed.
Then I suspected a wrong reading of the extruder temp, so I replaced the thermistor (had one spare available) but did not solved the issue...
Now I still have two idea. Either it is the stepper motor that have an issues or the TMC drive overtemp damaged the main board and I would have to replace it...
I don't want to wast too much money on replacing part that may be ok, so I am asking for your help if you think I have an other options to go through before.
Thanks in advance to all of you who may help me 🙂
Attached is the picture of my last print after having changed the thermistor 
Best Answer by PALM:
Ok, so I had time during the weekend to perform further investigation.
First I completely dismantled and cleaned my hotend as a friend suggested a kind of heat creep issue.
After having reassembled the hotend I did my first layer calibration and something very interesting happened.
In a normal ambiante temperature I had extrusion issue.
I decided to just try to extrude 100mm of filament and watch what was exactly happening. I was able to see the motor shaft turning but from time to time the filament wasn't going through the hotend. I tried to push the filament manually and it was flowing through to hotend without issue.
I dismantled the extruder idler in order to clean it when I finally found the issue. @Dan your concern about the PETG part integrity was founded... The side of the extruder idler deformed with the heat and the tension from the spring, what led to a bad driving of the filament.
The pulley was not in its correct location any more and it even grinded the extruder idler PETG part.
Hopefully I had an old extruder idler part from MK3S before the "+" upgrade and I have been able to install it. I reprinted to correct extruder idler and installed it, now I don't have issue any more. I learned that ambient temperature might be a big issue for part integrity.
Thank you for the support and the suggestion.
RE: Under-extrusion and TMC drive overtemp
Sounds like you cooked it good. At those temps, I'd worry about the integrity of most of the PETG parts - but that's me. ASA does not need such high environment temps - my enclosure rarely over 34 C or so. Do think about venting your enclosure outside - a few active carbon filters are good for about an hour.
RE: Under-extrusion and TMC drive overtemp
The integrity of the PETG parts seems to be ok. The prupose of the enclosure was not to keep an hot environement, but to prevent fumes from the ASA. My printer is in my living room and ASA doesn't smell that good. I have two small fan draining the hot air out of the enclosure through a carbon fiber sheet and 3 blowing fresh air inside. It seems to help a bit but still have issue. Even if it was a bad idea to print in such high temp environemnt ASA was priting very well before I got the TMC overtemp fault. should I worry about the main board integrity and replace it or this replacement is useless?
I still have about 50h of ASA parts top print then I would be able to get back to PLA/PETG where enclosure are not needed.
Thanks for your help
RE: Under-extrusion and TMC drive overtemp
Ok, so I had time during the weekend to perform further investigation.
First I completely dismantled and cleaned my hotend as a friend suggested a kind of heat creep issue.
After having reassembled the hotend I did my first layer calibration and something very interesting happened.
In a normal ambiante temperature I had extrusion issue.
I decided to just try to extrude 100mm of filament and watch what was exactly happening. I was able to see the motor shaft turning but from time to time the filament wasn't going through the hotend. I tried to push the filament manually and it was flowing through to hotend without issue.
I dismantled the extruder idler in order to clean it when I finally found the issue. @Dan your concern about the PETG part integrity was founded... The side of the extruder idler deformed with the heat and the tension from the spring, what led to a bad driving of the filament.
The pulley was not in its correct location any more and it even grinded the extruder idler PETG part.
Hopefully I had an old extruder idler part from MK3S before the "+" upgrade and I have been able to install it. I reprinted to correct extruder idler and installed it, now I don't have issue any more. I learned that ambient temperature might be a big issue for part integrity.
Thank you for the support and the suggestion.