As I mentioned in another thread, I donated a Mini to a local elementary school. We printed the octopus with the short length of HIPS included with the printer, then switched to PLA and printed a couple of disks with that. Both prints went well using the stock Lulzbot profiles for each filament. On the first attempt to print something with the a few days ago, the Mini went through it’s auto-leveling sequence (supposedly normally, but I was not there to see it). When it started to print, the print head moved into position then lowered the nozzle into the PEI surface and wiggled around a bit, melting a hole in the PEI. I came in about an hour later and fired things back up. There was some nasty thumping and vibration when we tried to run it through an auto-leveling sequence.
We seem to have two problems:
(1) What caused the nozzle to crash into and melt the PEI
(2) We can’t seem to get the filament out: We heated up to the print temperature for PLA. I tried to push a bit through to manually extrude some filament, but it wouldn’t budge. It also won’t let me pull it back out. We tried a variety of temperatures from 160 to 230˚C and it won’t move either in or out. I’m wondering if the heater or heat sensor (thermistor?) got damaged when the nozzle was melting the PEI and it’s now not getting up to the stated heat. The Cura screen shows it has reached the set point, but it sure isn’t acting like it. If a piece of the PEI melted into the nozzle I suppose that could be part of the problem, but I would think I could still pull the filament out.
I’ll be picking up the printer on Sunday, and hope to do a bit of trouble-shooting and clean out the old filament. I’ll put in a call to tech support once I have the printer in my hands. I thought I’d see if anyone here had any thoughts.