3:1 Geared Bowden Extruder

myminifactory

Here is a design I have been working on for a geared bowden extruder capable of pushing flexible filament such as TPU. I printed everything with 25% tetrahedral infill in Cura. Four top/bottom/wall shells. Zero point two millimeter layer height. Some of the fittings are a bit tight and some parts may need some cleaning after printing. Use supports everywhere ten percent lines in Cura as they are quite easy to remove and help with some parts. 1: Attach the gearbox part to the bowden motor mount (I use https://www.thingiverse.com/thing:2369063) attached to your frame using either four M three by ten millimeter bolts or other suitable bolts. 2: Fit bearings into main body and top cover, they should push all the way in with a little persuasion. 3: Fit an M five bolt into spur gear and push all the way in. Slide one of the washers on after the spur gear. 4: Push an M five bolt with spur gear attached into bearing in main body from rear. 5: Fit Mk seven extruder gear to M five bolt and line up with filament holes in main body, it can help to mark where this lines up with the holes and file a flat spot for the grub screw but this is not essential. 6: Assemble arm, put an M three nut into hole in handle and thread twenty- to twenty-five millimeter M three bolt in to it from the other side. Put another M three nut into hex hole on adjuster cog and bolt onto the twenty- to twenty-five millimeter bolt. Push larger bearing onto the stub at the other end of the arm and then push the stub on arm retainer into the top of the bearing. 7: Attach arm bushing to main body with an M three by ten millimeter bolt from rear. You may need to clean this part up a bit so it fits nicely into the hole on the arm. Slide assembled arm onto the bushing once attached and insert spring between the adjuster and hole on the main body. 8: Fit top cover to main body using four M three by ten millimeter bolts. Put an M five washer on M five bolt on top of bearing in top cover then bolt M five nylock nut onto M five bolt. Do not overtighten. The bolt should be able to turn freely with no pressure on the arm. 9: Fit assembled extruder to gearbox using four M three by ten millimeter bolts, paying attention to the orientation of the push on gear for the stepper motor. It will only run one way. Attach the pneumatic couplings to main body. You may need to use a spanner as they are a tight fit at first. 10: Calibrate extruder steps per millimeter. Mine is three hundred sixteen point six six for PLA and three twenty-seven point five nine for TPU. Leave any comments and suggestions in comments section please. Required parts: Thirteen M three by ten millimeter cap head bolts One M three by twenty- to twenty-five millimeter cap head bolt Two M three nuts One M five by forty-five millimeter bolt One M five nylock nut Two M five washers One stock Anet A8 extruder spring. (about eight point five millimeter diameter and twenty millimeter long) One Mk seven extruder gear. Thirteen millimeter tall, twelve millimeter outer diameter, ten point six millimeter inner diameter, five millimeter bore Two PC four-M six pneumatic couplings One sixty-eight bearing (I used sixty-eight ZZ) Two sixty-two five bearings (I used sixty-two five two RS) Check out this 3D printer support group for help with your settings or anything else printing related: https://www.facebook.com/groups/1843740479205162