Mini 1 not printing

Hey guys!

I recently purchased a Mini 1 from a craigslist post. The original owner had it for a year, printing ABS just fine until he switched to PLA and has had issues since, hence the acquisition.

After troubleshooting a bit, Here’s what I’ve done and what the printer is currently doing.

1.Downloaded latest Cura and updated the printer’s firmware.
2.Ensured the correct printer is selected in Cura.
3.Heated the Hot End and extruded any remnants PLA/ABS in the hot end.
4.Manually controlled and tested bed/printer functionally.
5.Attempted to print rocktopus, but printer fails to bring hot end to proper temperature even though I can manually set it to 220C and printing never begins.

I’ve taken the printer assembly apart and reinstalled everything. After plugging everything in, it responds well, extruding happens, can set the hot end to any temperature. Once I load rocktopus, it starts to bring temperature up but stops several degrees before and nothing happens.

My co-worker believes this might have to do with a thermistor that needs to be replaced. He also has a mini 1 and has experienced similar problems. It wasn’t until he replaced the thermistor were his issues resolved. I’ve looked for a thermistor but they’re not very easy to find. I’ve thought about letting LulzBot fix whatever is going on with this and send me the bill, however, before I do that I’d like to ask the community and their thoughts on what I can try.

Thank you all!

The temp needs to reach the set point before the printer starts although mine does it’s nozzle wipe at about 140 deg I believe.
When you manually set it to 220, does the nozzle reach that temperature?

The thermistor controls the temperature so… makes sense that’s the problem if it’s not reaching temperature. Double check all the wiring connections.

Yes, the nozzle will reach the 220 degrees. I’ll even instruct it to wipe the nozzle at 140, but when it comes to printing rocktopus it begins to reach the desired temp but never makes it. It just stalls and doesn’t want to respond to any of the commands.

Thanks. I checked the connections and they all appear to be connected properly. Not sure why it stalls when rocktopus is uploaded. The previous owner believes it has to do with the software, but I’m not sure why that would make sure after flashing the firmware with the latest version. Anything else you think I should check?

It wasn’t very easy to find the thermistor for sale. Luckily I found a website that sells them but is currently on back order until 1.20.2020.

Have you tried printing something else? Could the rocktopus file be corrupt?

Possibly. I’ll look to print something else. Thank you!

If the nozzle is reaching its set temperature than the thermistor wouldn’t be bad and is working. Perhaps it’s waiting for the bed to reach its temperature, what is the bed (build plate) temp set to? How long are you waiting after the nozzle reaches 220 before you decide it’s failed? How are you seeing the nozzle temperature? I assume there’s no LCD screen attached and you’re using the console window, Ahhh you’re seeing the temp in the Cura software. Bed temp for PLA should be only about 55 or 60 deg C.

I have never connected my Mini directly to a computer but always through Octopi running on a RaspPi. Using it you can watch the temperature ramp up to set point and stabilize there. Can you see it the same way when directly connected to a computer using USB?

Yes, on Windows Cura Le software you can see both extruder and bed temp. Gcode M105 & M155 is supposed to report the temperatures, run via the console window in the Cura LE software, but I couldn’t get it to work. I haven’t tried with a live print though. I’m not familiar with the Octopi software, can you see the bed temperature too?

Yes you can see both the bed and nozzle temp and it displays a graph of them both. You can also start , pause and stop the print and move the nozzle to wherever you may want it and retract and extrude filament. I like it a lot. It’s WIFI so I can check on the print on my ipad or phone although I tend not to leave the premises while it’s printing. I also have a USB camera connected to the RaspberryPi so I can watch what’s going on from another room.