BCN3D Sigma bowden tube retention fitting by freddotu

Last crawled date: 3 years ago

8 July 2016 EDIT:
I've created an edit lower in this document with a metal shim that performs better, but may be challenging to construct without suitable tools. Due to that complication, I've also created a 3d printable shim here:http://www.thingiverse.com/thing:1664774
It also works better than this threaded version, but I've left the threaded version in place, perhaps to assist someone else with a similar need, but not precisely this application.
A remix of sorts, although not by much. I took the concept from StikDesign and "streamlined" it a bit, removing material and reducing the amount of support (and time) necessary to accomplish the same result. Credit goes to StikDesign for coming up with the threaded tube concept, an elegantly simple solution for a nuisance of sorts.
The BCN3D Sigma dual extruder printer is a work of technological art. The prints are beautiful, even at 300 micron layer height. I understand that a few machines suffer from bowden tube creep and release, as did mine.
This fitting, properly created, processed and installed, solves the tube creep.
Another EDIT!
I wasn't happy with the weakening of the bowden tube, nor with the need to recalibrate after each bowden tube removal. With a suggestion from MatterHackers, I came up with the added item to this post.
It's a conventional feeler gauge from the auto parts store. This one is 0.88 mm thick, which appears to be nearly perfect to apply gentle but firm lifting force to the underside of the gripper release ring.
I used a series of drills, ending with 8.5 mm. Unfortunately, the feeler gauge is made of seriously strong grade steel and I pretty much destroyed the cheap bits from, well, where does one buy cheap stuff today?
With help from an abrasive cutting wheel, I chopped open one end, tapered the "fingers" and cleaned up the burrs. Using the TLAR method, a mid-point cut and two ninety-degree bends, the result is superior to my printed fitting.