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Ultra-light extrusion : toward the Graal...

A project log for Folds and Hinges Technology to Make Mechanisms

Engraving by CNC a special composite, the Hylite, to create folds and hinges. Zatsit, so made, is on Kickstarter until oct 5, 2018. Hurry!

Marc PeltierMarc Peltier 06/12/2018 at 12:231 Comment

Zatsit works even better when the effector is light, especially as a 3D printer. So I try to find ultra-light solutions, without any compromising on the very best functionality.

The extruder is one of the components that most influences the quality of 3D printing. Ideally, the filament should be pushed by the extruder as close as possible to the area where it will be melted, so as to avoid inaccuracies in the extrusion caused by the elasticity of the various components present on the guide path, including the filament itself. Delta 3D printers are at a disadvantage in this regard, as it is not possible to install a sufficiently powerful extrusion assembly directly on the printhead, due to the associated weight.

In addition, the extruder must drive the filament in a powerful, efficient and precise manner, which is best achieved by pinching it between two symmetrical hobbed gears.

The prototype system I propose today meets these two criteria: two symmetrical hobbed gears are driven by the same worm gear, in a compact and very light unit, located just above the water-cooled Hot-End. The filament is pushed within 25mm of the melting zone. 

The worm gear axis is driven by a flexible shaft connecting it to a stepper motor, flexibly suspended, and gimballed, between the three carriages of the delta linkage. In this position, the center of gravity of the stepper moves very little, and its inertia is thus neutralized ("Flystruder").

The extrusion mechanism is mounted floating on a Hylite support which also carries the water-cooled Hot-End. It is the filament that automatically centers the extruder mechanism on the extrusion path.

This device is therefore very close to the Graal of Delta 3D printers: a powerful, precise, and above all DIRECT extrusion head, that is also ultra-light.

Here, the whole unit weighs only 32g, including the support, the extruder, the Hot-End, and the cooling of it! Yes, 32g! This is about one-tenth the weight of a conventional direct-drive extrusion assembly, which does not always have a double hobbed gear drive!

As a result, the ratio between speed and print quality is still improving...

Discussions

Daren Schwenke wrote 06/12/2018 at 13:23 point

That is one sexy filament drive right there... Good job.

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