Large Scale Fused Pellet Fabrication

A common idea

Large scale 3D printing is one of the most frequent ideas popping up on forums.reprap.org. Most of them use filament, most use delta-style frame (scales easily upwards). Like this: [1] and this: [2]

Engineering difficulties

• Hot end won't transfer heat infinitely fast, limits extrusion rates
• Making lots of filament is slow and expensive, so pellets/granules are preferred
• Frame gets heavy
• Since pellets can't retract, nozzle lock mechanism must be implemented if drooling is to be avoided

Open Source Status

Pellet extruders

Most common in Dec 2015 is RichRap's Universal Pellet Extruder design: [3] there's even people selling it in Italy: [4]

Hackebik project seems to roll its own pellet extruder: [5]

Old failed RepRap attempt: [6] [7]

There's also a long report focusing on RepRap application: [8]

Induction heated hot ends

An old Master's with some nice data (couldn't find actual thesis): [9]

A newer implementation with full and explained schematics: [10]

There's a lot of old discussion on the forums about this: [11]

Note that I (Tobben) am unsure whether induction heating is needed/good.

Frames

Large printers get clunky and expensive because smooth rods and aluminum extrusions need to be really thick to give the needed rigidity. Presented delta style designs get around that by mainly scaling in one direction (Z). RepRap Clerck get around it by being cable driven and using already built rigid structures as its frame: [12]