Hi everyone! This is my latest design, a high precision direct extruder using a planetary gearbox plus the big (12mm diameter) dual drive bondtech style gear-set.
Short spek:
Gear ratio - 7.5 (new option 7.2)
Filament pushing force 120Ncm (theoretical) - 12.4 Kg (Wantai stepper)
Filament pushing force 103Ncm (theoretical) - 10.5 Kg (LDO stepper)
Filament acceleration up to 660mm/s^2
Retraction speed: 60mm/s
Overall weight is about 140g
The extruder is driven by a small round nema 14 stepper (86g, 1.88A 13Ncm, Wantai stepper option).
The orbiter printing @ 200mm/s on my MachCube 2.1:https://youtu.be/aZolOWtBbME
In the last months I have experimented with worm gear based extruders with very good results, however not perfect so I decided to go for a different approach.
What I have learned is that the worm gears are not the best choice for extruders. Although high gear ratio gives a good theoretical filament pushing force in reality this is not always true, mainly because the worm gear efficiency is pretty low.…

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