Revised Runout Detector and Combined Guide Bearing for Ender 3

thingiverse

As per the title, this is a revised version of my design at https://www.thingiverse.com/thing:3995249 I've made it a remix because the original Thingiverse page was getting cluttered and confusing! The basic geometry is unchanged: It still consists of a bracket, a switch/bearing plate, and a cover - I've done away with the Z-rod guide as, in practice, it's redundant; the entire assembly already keeps the filament away from the Z-rod. It also uses the same switch, bearing, and mini-cable tie (for cable routing). The switch is a CK Unimax MML1 changeover switch. The bearing is a standard 608 skateboard type. The changes from the original design (and its later revisions) are as follows: The mounting bracket is slimmed down to look less bulky, to use less filament, and to decrease the overall print time. The cover plate clips are now longer. The clips of the original cover would slacken over time, and any large movements or filament jerks, etc, resulted in it shooting across the room mid-print! This allowed the filament to escape and trigger a false alarm. Because the clips are now harder to release, they are designed to protude just enough from the switch plate that you can use your fingers to gently lever to make removing the cover easier. The switch plate was altered to accommodate the new clips. But that isn't the end of the story. It was also revised to allow its removal and replacement without having to disconnect any wires. My wires all run through a cable chain (thanks Johnniewhiskey - best design ever!), so it saves lots of irritating dismantling and reassembly! The microswitch positioning pins have been replaced with metal pins. The layer lines of the original design made them weak, and prone to snapping off. It was tricky finding some pins to closely fit the tiny holes on my microswitches. But I eventually found some masonry nails that were perfect. All I had to do was to shorten them with a Dremel. They push through from the rear of the plate (glued if necessary), and work a treat. One word of advice though: If the switch doesn't quite line up, don't force it! As I found out the hard way; the switch bodies are brittle. If the pins aren't aligned, gently file BOTH backing plate holes, in tiny increments, until the switch slips over them without binding. I think that's everything... For now! The trouble is that I just can't help tinkering with this design when I've nothing better to do!