Sometimes it’s tempting to buy the cheapest possible 3D printer filament, but that’s not always the best idea.
Plastic is literally a commodity these days, but when its formed into spools of 3D printer filament, we don’t think so. There are many characteristics that make up “quality” filament.
One terrific resource for understanding the nature of quality is a piece from a few years ago by ProtoParadigm, a well-known supplier of good quality 3D printing filament. They go into great detail to explain - sometimes with detailed mathematical formulas - exactly how filament is extruded and how bad filament manifests printing errors.
Of course, the key parameters of quality must be the consistency of the filament’s diameter and the roundness of the filament. Variations in either result in under or over extruding. That means gaps or blobs, respectively.
What’s great about ProtoParadigm’s piece is the detailed graphics that show, in some detail, the effects of poor filament. They go over every filament failure scenario with both illustrations and attempt to derive the amount of extrusion error mathematically (a portion of which is shown above).
Whether you purchase your 3D printing filament from ProtoParadigm or other suppliers, the scenarios described by ProtoParadigm may occur if you encounter poor quality filament.