MKS3+ Extruder Issues
Good morning! I've been trying to track down an issue with my MK3 extruder and I'm rather at a loss.
I replaced part of my hot end earlier this week due to a broken thermistor wire giving intermittent readings. New thermistor, new heat block, heat break and nozzle. I initially got the gap wrong and had oozing, so had to tear it down again and redo it. I then noticed an under-extrusion issue - during initial layers on flat items, extrusion would become very patch. I initially ascribed this to a dirty sheet and bad bed leveling, which I cleaned and recalibrated, but eventually tracked it to a loose grub screw on the extruder motor's bondtech gear. I took the opportunity to clean both the extruder and idler gears with some compressed air.
However, despite all this, I'm still having an issue and I'm wondering if the motor itself is having a problem.
A calibration cycle runs fine. Printing a test cube runs fine. This morning I tried printing a larger item - a ~1.5hr print for a project I'm working on, and the issue appeared. A little over an hour in, extrusion just stopped. No alert appeared, the print head kept moving, but the extruder stepper itself appeared not to be moving (I have an indicator on it to make it easy to see).
I stopped the print and had the printer unload the filament. It thinks it has, but I get no motion from the extruder motor, and an attempt to pull out the filament by hand doesn't work. It's stuck. I have to press the screw to release the bondtech gear and then it comes right out. Before I started the print, the extruder ran fine.
Attached is a video of the behavior when unloading.
Given all this I'm suspecting the extruder stepper is seizing up after a period of operation (ie: heat). Any possible fix to this or am I better off replacing the stepper?
Will note all this testing, and almost all my printing, is with PLA, in a LACK enclosure. The extrusion issue is new as of this week.
Thanks!
RE: MKS3+ Extruder Issues
Do you close the door ? PLA needs the door open to avoid heat creep.
Formerly known on this forum as @fuchsr -- until all hell broke loose with the forum software...
RE: MKS3+ Extruder Issues
I run prints with the door closed, opened it to take the video so I could reach the controls.
To my understanding, heat creep wouldn't stop the extruder stepper from trying to extruder, would it? It would just make the filament too soft to be pushed out, so the extruder would rotate and nothing would come out.
RE: MKS3+ Extruder Issues
Turn fillament sensor off put no fillament in and start a print if motor stops with no fillament replace motor if it's fine let us know to help further
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RE:
Tried that and no dice.
Printer had been off for about eights hours. Powered on, set filament sensor to off, asked it to load PLA at 215c. Came to temperature, heard some sound from the extruder stepper but no motion on the indicator dial. Tried again with the idler door removed to take the attached video, you can see the stepper side isn't turning at all.
RE:
Could be a clogged nozzle. You could try to heat the hotend to a really high temp, like 270 °C or so. If you are lucky the filament in the hotend will just drip out and you can use the needle from the supplied tools to get the nozzle free. If that does not work remove the nozzle and heat it with a lighter flame or a heat gun while holding it with pliers. This should burn the residue out. I had to do this a few times with CF nylon filament. I used a lighter flame.
RE: MKS3+ Extruder Issues
Probably faluty motor then contact prusa through live chat @walter-laher it's not a clog watch previous video motor won't spin Even no fillament
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RE:
Ah, the video did not work for me at first. But that looks like a dead motor. Did you make sure that the extruder motor cable is connected correctly? You say that you worked on the electronics box, and the problem started after that. Perhaps a contact/plug came loose there? In the instructions for the mk3s+ upgrade the manual says that the nylon filament that stabilizes the cable bundle should not touch the plugs in the electronics box because that can cause a bad contact.
RE: MKS3+ Extruder Issues
Thanks for the gut-check. I'll reach out to Prusa Support and see what they say. I've had the printer for roughly a year, not sure what they'll say warranty-wise.
RE: MKS3+ Extruder Issues
Keep us updated
Please help me out by downloading a model it's free and easy but really helps me out https://www.printables.com/@Hello_474427/models
RE:
Hello! Based on the information you've provided, it's possible that the extruder stepper motor on your 3D printing press is overheating and causing the filament to jam. This can happen if the motor is working too hard or if it's not getting enough cooling.
One thing you can try is to reduce the printing speed and/or increase the cooling fan speed to see if that helps. Additionally, you may want to check the wiring and make sure that the stepper motor is properly connected and receiving enough power.
If the problem persists, you may need to replace the stepper motor. In that case, it's important to make sure that the replacement motor is compatible with your printer's specifications.
Lastly, it's worth noting that printing PLA in a 3D printing enclosure can cause issues with overheating, especially if the enclosure doesn't have proper ventilation. You may want to consider adding additional cooling or opening the enclosure during printing to help dissipate the heat.