An extruder with a stepper motor is used in my Pusa I3 and also in almost all 3D printers. I decided to develop a lighter extruder drive based on a 3-phase linear actuator with a magnetic Halbach array. It is designed to directly replace NEMA17 in any 3D printer. I wanted to use VCA (Voice Coil Actuator) as a drive, but VCA is very expensive and weaker than the drive with 3-phase coils and a magnetic Halbach array.

https://youtu.be/aeM0KQuF120

Features of the extruder drive:

• High Force to Weight Ratio
• High continuous and peak forces
• Weight 4.2oz (119 grams)
• High Accelerations
• Halbach Array magnetic system
• Scotch Yoke mechanism.

For a full description of the drive, see here: http://www.instructables.com/id/Linear-Direct-3D-Printer-Extruder-Drive-Fusion-360/

We need 5 Neodymium Rare Earth magnets 5X5X25mm N42 magnets or use compound magnets, they will need 10 pieces. https://www.indigoinstruments.com/

The diameter of the wire can be changed if a larger force is required, but the consumption current will increase. Tests with a 3-phase bridge driver showed that the drive effort is sufficient to operate as an extruder drive. This is an experimental device, work on it continues.