Started printing this filament shrinkage test and had to leave the house. When I came back, the whole upper half of the part had shifted after the first few layers, and it left two solid blobs attached and one ball of spaghetti. The magnetic bed doesn’t appear to have moved. Part is still solidly adhered to the print bed. How did this happen, and how can I keep it from happening again?
You unscrew your extruder, heat the hotend up until you can barely push the plastic across (~170ºC for PLA, ~180°C for ABS), push a bit of it and then pull it out.
Cut the end of the filament and do it again, a few times.