My take on a 1.75mm filament Bowden Extruder drive. I have run the Airtripper, and the PlanetCNC variant Bowden Drives. They work well, but I wanted a few things:
1.) Backside access to the hobb gear teeth for cleaning while filament is loaded, or even during a print.
2.) Option to drive off a Nema17, or a Gear-Reduced Nema17 which uses a different bolt pattern.
3.) Alternative to push lock tube fittings to hold the bowden tube, allowing it to extend beyond the hold point (i.e. pass through hold down). I am using a 4mm nut instead.
4.) Support the filament as close to the hobb & bearing as possible without interference.
Available File Types: Zip - Pack and go of the full Solidworks 2014 Assembly, STL’s, Step
Aside from the printed parts for the Nema17 version you will want:
1 lot of 4mm OD, 2MM ID teflon tube
qty:2 - 4mm Hex Nut
qty:4 - M3 Flat Washer
qty:2 - M3 Oversized Flat Washer
qty:2 - M3x10mm Button Head Screws
qty:2 - M3x12mm Socket Head Screws
qty:2 - M3x35mm Socket Head Screws
qty:2 - M3x50mm Socket Head Screws
qty:2 - Springs (I used Mcmaster# 9657K283)
qty:1 - 608 skate bearing
qty:1 - Ultibots 1.75mm Hobb Gear
If you go with the Planetary setup add:
qty:2 - M3x10mm Button Head Screws
qty:2 - M3 Hex Nut
qty:1 - replace ultibots hobb gear with 8mm ID hobb gear like the Mini hyenas gear from makers tool works.
One note: When you thread the 4mm nut around the 4mm bowden tube it will compress on the ID. Get a small drill bit around 2mm and ream the bowden tube back out in that area…
https://www.youmagine.com/designs/hercustruder