fluidity bowden 1.75mm direct drive extruder.

thingiverse

There are plenty of decent struder designs out there but nothing quite meets my needs.\nMy requirements were very specific:\nA 9mm x 4mm x 4mm thick brushless motor bearing that can be found at http://hobbyking.com/hobbyking/store/__10201__HK_500GT_Ball_Bearing_9_x_4_x_4mm_Align_part_H60103_.html \nA 10mm fine pitch bowden clamp for tube suitable for a 4mm OD tube which can be purchased at http://www.robotdigg.com/product/348/Heavy-duty+push-fit+bowden+connector+4-01 .\nThe perfect motor is long direct drive, has 400 steps per rev and operates on low voltage with a Nema 17 rating: http://www.omc-stepperonline.com/9deg-nema-17-bipolar-stepper-44ncm623ozin-17hm191684s-p-12.html .\nThe struder needs to be side mounted.\nI finally managed to get it set up this weekend, left it printing late at night and was thrilled to find it worked perfectly on the first try. I am really enjoying it!\nThe clearances along the 1,75mm filament are intentionally minimised so that I can print with Ninjaflex, etc.\nIt's essential to insert a stiff spring between the base nipple and the swing arm nipple in order for the roller and filament to press firmly against the pinch roller.This setup uses a 10mm diameter pinch roller, but don't over-tighten the grub screw until you've got some filament running through the cavities so that it holds the pinch roller in place.\nThe swing arm has a bridge support built into it which needs to be removed before the bearing is installed. Additionally, wind down your motor current a bit before installing the stepper motor. The longer length provides great torque.\nUse 1 x m3 x 16mm screw along with an m4 nut as a washer, and also use 3 x m3 x 8mm screws plus one m4 x 10 bolt for the bearing. If you can't find a ready made spring, it can be wound from piano wire. My spring measures 10mm in diameter, 1.24mm in wire diameter and 19mm in uncompressed length.