Geared Bowden Extruder | Aluminum Extrusion Mount

thingiverse

This is a custom-designed bowden extruder that I created. It's optimized for 1.75mm filament, unlike most geared extruders which are designed for 3mm filament. I've found that the higher torque and resolution in movement make it a better choice for me. After using a geared extruder for some time, it would be difficult to switch back to a direct drive. When designing this extruder, several factors were considered: ease of use, easy loading, ability to extrude flexible filament, compatibility with stock spline gears, and mounting on 2040 extrusions. This extruder features a 12.7mm diameter spline gear driven by a 5mm shaft. Most geared extruders use larger bolts that require knurling for gripping the filament. I chose to use a spline gear because it works well and eliminates the need for grinding the bolt. The design is intended for use with my new frame made from 2040 extrusions. One issue with using a smaller bolt is that if the shaft is not smooth where the setscrew goes, the set screw may slip. I've found a solution to this problem by creating a system that doesn't require a setscrew. This design also allows for a removable gear shaft. To assemble the extruder, follow these steps: place the large gear on the 5mm bolt, then slide the bearing onto the gear until it's against the gear. Thread on one nut and apply red thread locker to the threads near the bearing but not on the bearing itself. Tighten the bolt to secure the bearing to the gear. Next, add a drop of red thread locker to the side of the nut that doesn't touch the gear. Slide the spline gear onto the shaft until it's seated. Thread another nut onto the bolt and tighten it snugly when there's a small gap between the nut and the gear. Apply a drop of red thread locker to the side of the spline gear where the nut will be. Tighten the nut as much as possible, then let it sit for a while until the spline gear is securely in place. This system will not move once it's assembled. The bolt can also be installed through the body of the extruder, and the bearing can be placed in the back plate. Additional parts needed for this project include: * Extruder gear with an outer diameter of 11-12mm * Two 625zz bearings (5x16x5) * One 608 bearing for the filament idler * One 50mm M5 bolt or longer * Two M5 nuts * One M5 nylon lock nut * One 5mm washer * Two springs with a diameter of 3-4mm, used as tensioner springs * Two screws long enough to secure the tensioner springs * Two washers to keep the springs in place Note that no nuts are needed on the other side of the tensioner block. I designed this system to thread into the plastic, but if it wears out, a nut can be used instead. You may need to re-tap the threads for the slip fitting, as a 0.04 nozzle is too large for the finer details required. However, simply tapping the beginning of the threads will get you started. This extruder body was designed from scratch, based on Condac's extruder that I previously remixed. I used his idler arm, idler shaft, and gears because they are well-designed and have been widely used on Thingiverse.