I have a kickstarter version of the A350 that I got back in 2020. I use it as a hobby and it may be printing 2 days a month. Over the last month bigger prints that take longer than 4 hours or so just randomly stop printing.
I usually print through Luban over wifi, but it happens even if I send the print to the console, or print from the USB. In the middle of the print, the display will show percent complete but will have a popup showing Pause or Cancel. The printhead has moved back to the top start position and heated bed and printhead will be off. I usually start a print at night, so I haven’t witnessed it happening in person. Pressing Pause returns that the print cannot be paused, all I can do is Cancel.
I think I’ve narrowed it down to either the printhead or power supply overheating and causing a fail. I’ve downloaded the logs, but they don’t seem to show a failure.
The fan on the printhead sounds like it’s breathing, it fades in and out. The extrusion looks normal throughout the print, no clumping or anything. So the hot end should be fine. But I’m not sure if it’s maybe a thermal breaker tripping during the long print or it’s something the power supply. Can anyone make some troubleshooting suggestions?
I would buy a replacement printhead, but I don’t see the single extruder version for sale anymore and price for the dual head seems pricey.
My work-around lately has been to measure the height that did print, re-slice the model and lower the printed version below the bed level, print from there then glue the pieces together. It’s not pretty.
Note that I’m not sure if that’s still the case, but luban’s console used to be more verbose when connected directly to the printer via USB. So maybe leave the console running during the job and see if any error messages (or an explicit interruption cause) comes up?
I have not tried to recover by powering down. I’ll try on the next fail.
Attached are logs from the past few days. You can see a quick 1hr successful print on 7/27, then the next print fails. I don’t have a lot of experience on what’s going on these logs though.
The firmware log identifies the failure directly. After printing for 6 h 4 min it reports Thermistor of hotend[0] maybe come off! temp: 196.30 / 215, then commands both heaters to 0 and stops. A subsequent print is rejected with System Fault! Now cannot start working!. Check/reseat the hotend thermistor first, then inspect its thin wires, internal connector and toolhead cable for an intermittent connection. If those are sound, test or replace the heater tube; Snapmaker specifies 13.6–15.3 Ω. This appears to be thermal protection doing its job, not a slicer or model problem.
Also, if you’re printing PLA you may want to consider leaving the enclosure door at least partially open. A fully closed enclosure printing for 6h will turn into an oven and slowly drive all temperatures up. Heat creep can be a pain in the rear.