Difference between revisions of "MK5-6 STEPSTRUDER NEMA 23 DIRECT DRIVE PIVOTING FILAMENT PUSHER (Q43833)"

This is a direct drive extruder mechanism that fits with the hotend and dinos of a MK5-6. I wanted to move to a stepper drive extruder but didn't want to wait three weeks for makerbot to ship their new beefy nema 17. I also had a lot of issues with the delrin plunger. I liked the idea of a ball bearing to provide the pressure between the filament and the drive wheel as in a wade's but didn't like the 4 bolts to adjust to change filament. My other design goals were to leave everything as accessible as possible and provide some mechanical advantage where it makes sense. The worm grove in the drive gear is made very close to the face of the motor while the motor shaft ball bearing rides at the end of the motor shaft while having the shaft pass completely through it. I also increased the length of the teflon guide tube to come to right below the drive wheel. The pivoting arm that applies pressure to the filament forcing it against the drive gear allows one screw and spring pair to take the job of four. It also means that the screw can be backed off completely and the arm rotated out of the way to provide access without having to be completely removed. The relative positions of the bearing and tensioning screw on the arm give something like a 2:1 advantage of filament pinch strength vs spring force. I also included a hat that accepts a piece of sponge or similar to remove dust from the filament as it is being drawn into the extruder. The hat as well can pivot out of the way and has a sloping bottom to make it simpler to feed new filament through. The sizing for everything is imperial in this case but I can make other versions is people have specific requests, I'll also include the source files.