[Students, Faculty and Staff] Just prior to printing, the Ultimaker 3D printers extrude a blob of filament on the front corner of the bed — front left for extruder 1 and front right for extruder 2. Ideally, the blob will adhere to the glass and remain at the front corner. However, sometimes the blob can be dragged back into the printing area by the print head. If this goes undetected, it can cause the print to fail.