Direct Drive Bowden extruder for Mk8 drive V5 by KDan

Last crawled date: 3 years ago

This part is designed specifically for an Mk8 drive gear with an effective drive OD of 7mm. It attaches directly to the motor and has no provision for attachment to the machine since that may be different for almost everyone. I'm using mine on a Kossel 2020, and therefore I used my Kossel 2020 extruder stepper mount. http://www.thingiverse.com/thing:783695
I've tested this extruder and drive gear for over a year now and have done prints as long as 16 hours with it.
This design incorporates a solid body to facilitate completely enclosed teflon guide tubing. Maximum filament support was desired to work better with flexible filaments. This is intentionally not an open, minimal design like you see almost everywhere else.
See instructions for a list of required parts and assembly information.
Modeled in DesignSpark Mechanical.
UPDATE1: Fillet radius on tensioner arm mounting ears was increased to address concerns about strength.
UPDATE2
The arm has been beefed up and the idler bearing axis has been moved slightly closer to the drive wheel. This provides extra headroom for the tensioner arm so that it won't bottom out. The Ver 4a part seemed to be sagging over time and almost bottoming. This shouldn't be a problem now. Version 4a has been deleted and replaced with Version 5.
A separate version with a nutcatch pocket for an M3 nut has been added. The slot was made 6mm wide - in order allow a 5.5mm hex nut to be easily inserted. The hole will need to be reamed oversize for clearance of the M3 screw itself.
Version 5 is the last version uploaded to Thingiverse. The extruder has been significantly improved upon since then, but I have been advised NOT to upload it to thingiverse because the Makerbot/Stratasys empire and their herd of vulture lawyers do not respect intellectual property rights. They effectively claim ownership of anything uploaded here and they reserve the right to use, sell, or even patent it as their own, They have stolen extruder designs in the past when they saw something they could profit from.