Ender 3 Combined Filament Guide and Runout Switch MkII

Description

______________________________________________ February 2021 Please note: This design has been heavily revised to correct some niggles discovered over 15 months of continuous use. The much-improved replacement can be found here: https://www.thingiverse.com/thing:4765718 I leave this design here purely as a reference ______________________________________________ This design uses a miniature microswitch instead of the (relatively) bulky one in my previous design. This allows a significant reduction in the overall size of the complete assembly, resulting in a far more compact unit, but still allowing plenty of finger room for feeding the filament into the hole on the extruder mechanism. There is also an optional Z-rod guide, to keep your filament free from contact with the lubricant on the Z-rod. It works with both the standard extruder frame, as well as the slightly taller double-gear extruder frame (which has a slightly raised filament hole compared to the standard one). It is designed around this switch: https://www.ebay.co.uk/itm/Micro-Switch-Small-Miniature-1A-Gold-Lever-Microswitch-C-O-Changeover-MML1-x-1/293178384134?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649 - Hopefully it's a standard type which can be sourced outside the UK for those of you elsewhere in the world. The only other hardware required is a standard 608 bearing, such as you would find in skateboard wheels etc, and a pair of M3 machine screws with a thread length between 5 and 12mm. There are 3 printed parts (or 4 if you use the Z-Rod guide), and it is held together using just two M3 bolts. The bearing cover clips in place by itself, so it can easily be removed when required, and the (optional) Z-rod guide simply slots into the captive bolt hole on the rear of the main bracket - after the bracket has been secured to the printer! Note that you may need to use a spare bolt to draw the captive nut fully into the bracket hole, as it is a deliberately tight fit to make tightening of the carriage bolt easier. There are two cable tie fixing points to provide the user with options for cable routing. They are designed so that the clasp mechanism on the cable ties goes to the rear of the machine when fitted. Hopefully you will agree that this is a sensible evolution from my previous design, and that I haven't wasted the past week reinventing a perfectly good wheel! ________________________________________________________ October 2020 Update: After using this design sucessfully for about a year, I began to notice occasional false triggering. This became more frequent recently, and I traced the issue to my original design decision to make the bearing plate as thin as possible for neatness. Over time this had begun to bow, releasing pressure on the switch, and causing the false triggers. Easily solved! I've therefore added an updated stl with a significantly thicker switch plate. Whilst I was at it, I took the opportunity to add an additional radiused corner to the filament entry point, purely for aesthetic reasons. I've also added an updated bearing cover to match this change. There have been further changes since this update, and I refer you to the revised version located at: https://www.thingiverse.com/thing:4765718

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