Lotar's Dual Gear Extruder

thingiverse

This is an extruder born of necessity. I had hundreds of hours of (mostly) successful printing with a simple, direct drive extruder using a brass Mendel style gear. Sometimes, especially when using a small nozzle (0.2 mm) the extruder had a hard time pushing the filament. Using a small diameter gear (Mendel) there where no skipped steps, but filament grinding. So I decided to reinvent the extruder and dispose of the filament tensioner bearing and replace it with another pusher gear. If the filament would be pushed form both sides, it will result in less to no grinding. Due to the bearing sizes available to me, I moved from the Mendel gears to brass mk10 (clone) gears. This is the 4th iteration of this project and the first one that is easy to built and assemble. It works reliable as of 30 print hours ago, but I still consider this a work in progress as further testing is required. As a personal note, doing this, I learned to design gears (Pitch Diameter, Pressure Angle, etc.). The internet is a wonderful resource and only if you don't want to learn something you can't, otherwise, there's no excuse. After lots of design and testing of this extruder (I was on the 3rd iteration), I saw that I'm not the only one and certainly not the first to approach the dual geare extruder problem. But I think mine is smaller and hopefully better then the others. The extruder: To make the second gear work counter clockwise and in sink with the main gear I needed some kind of clockworks or belts. To keep it as small as possible I decided on gears. The clockworks is somewhat separated from the extruder part to prevent filament shavings from entering between the gears. For extra power and accuracy, I made a 3:1 reduction gearbox. Not wanting to generate a fresh pair of herringbone gears, I taken some from the beautiful 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