Assuming you are using 1.75mm filament, to get enough force to extrude reliably at high print speeds, you need one of the following:
- A non geared extruder with a high torque (about 60Ncm) motor, run close to its maximum current;
- Or a much smaller motor (20Ncm torque is sufficient) with gearing between 3:1 and 5:1.
So the advantage of gearing is that you can get reliable extrusion with a shorter, lighter and cheaper motor. I use geared extruders in both my printers.
Edited 1 time(s). Last edit at 03/30/2016 04:02PM by dc42.
Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod
Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].