US Patent 11267199 Filament drive and loading method for 3D printer

A low compressive force filament drive system for use with an additive manufacturing system includes a plurality of drives spaced from each other. Each drive includes a first rotatable shaft and a second rotatable shaft engaged with the first rotatable shaft in a counter rotational configuration. The filament drive system includes a pair of drive wheel, each fixedly attached to a shaft and comprising a groove about a circumference having a substantially smooth surface and positioned on opposing sides of a filament path with a gap therebetween so as to frictionally engage a filament provided in the filament path. The drive includes one or more bridge shafts, wherein each bridge shaft is configured to rotatably couple the adjacent drives of the plurality of drives, wherein the shafts are configured to be directly or indirectly driven by a motor. The counter rotating drive wheels pull the filament from a source and push the filament through a filament feed path to a feed drive in a print head without breaking or indenting a surface of the filament.