The UP 3D Printer extruder is notoriously known for getting very hot around the extruder gear. This heat softens the filament and the gear begins to chew out the material causing a nozzle jam. If you have the original UP Box we recommend upgrading your printer to include the improved part cooling fan. For the best results we also recommend printing PolySmooth using the ‘Fast’ setting in UP Studio with 0.15mm layer height.