Lotar's Dual Gear Extruder

myminifactory

I had a pressing need to create something new. I spent hundreds of hours with mostly successful prints using a simple, direct drive extruder equipped with a brass Mendel style gear. However, when I used small nozzles (0.2 mm), the extruder often struggled to push the filament through. Using a small diameter gear didn't produce skipped steps, but it resulted in excessive grinding on the filament. So, I decided to reinvent the extruder and get rid of the filament tensioner bearing, replacing it with another pusher gear. If both sides are pushing the filament, there's less or no grinding involved. Due to limited bearing sizes available to me, I switched from Mendel gears to brass mk10 (clone) gears. This is my fourth iteration of this project and it's the first one that's easy to build and assemble. As of 30 print hours ago, it works reliably, but I still consider it a work in progress since further testing is required. The extruder: To make the second gear turn counter-clockwise in sync with the main gear, I needed some kind of mechanism or belts. To keep it as small as possible, I decided on gears. The clockwork system is somewhat separated from the extruder part to prevent filament shavings from entering between the gears. For extra power and accuracy, I built a 3:1 reduction gearbox. Not wanting to create new herringbone gears, I used some from the NSTT Extruder by Paciente8159. Part list: 3x M3x30mm screw 2x M3x20mm screw 2x M3x8mm screw 1x M3x16 screw 1x M5x60mm screw (internal hex head) - preferably with partial thread 2x M5x100mm screw (to be cut for axles) - preferably with partial thread 1x M5 nylon captive nut 4 x M3 nut some washers 6x 695ZZ 5X13X4 bearing 2x 625zz 5x16x5 bearing https://youtu.be/sLyT0wXdCTk