CHOPPER : Open-Source Desktop Strand Cutter for Small Screw Extruders

CHOPPER is an open-source desktop strand cutter designed for preparing 3–4 mm feedstock for small screw extruders like Materium.
Built for dry cutting of PLA, PET, PP, even TPU.

CHOPPER is a compact, open-source strand cutter engineered specifically for preparing correctly sized feedstock for small screw extruders.
Unlike most DIY pellet cutters that generate ~7 mm pellets for molding or sheet-press recycling, CHOPPER produces short 3–4 mm pieces optimized for miniature extrusion screws where packing density, void reduction, and melt stability directly affect extrusion quality.

The machine uses:
– A carbide SCMT stationary knife for near-zero-clearance shear cutting
– A belt-driven transmission (no printed gears, no brass inserts)
– Soft silicone feed rollers for tolerance against irregular strands
– Adjustable knife clearance for reliable dry-cutting of elastic materials like TPU

This design allows CHOPPER to operate both:
– At high speed when driven by a drill
– Or at synchronized slow speed using a planetary stepper for continuous compounding workflows

By matching the output speed of small extruders, CHOPPER enables desktop-scale melt → cut → re-feed loops, making experimental compounding possible without industrial twin-screw equipment.

CHOPPER is fully open-source.

CAD files, assembly guide, and Bill of Materials will be released publicly on:
👉 https://metafuse.tech

The website is currently under construction and will go live in a few days.
Follow or subscribe for the release announcement.

This project was built as a companion tool for Materium Pellet Extruder, but CHOPPER works with any small pellet extruder that benefits from short, uniform feedstock.

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