Limit switch bracket/support

thingiverse

**September 2019 UPDATE** I upgraded my Z axis limit switch and needed this part to be 5mm longer. I updated the OpenSCAD file so changing the length (and a few other properties) can be done by changing variables. This will also work with the Thingiverse Customizer - if it's not broken. This change includes: * Added variables to the SCAD file for easy manipulation of the overall length, girth of the platform, height of the shelf risers, gap between the risers, whether or not the nut trap is rendered, and on which side of the model the nut trap should be rendered * Rounded 90 degree angles on the neck for added strength * Added an M4 nut trap * Added a rendered model that's 5mm longer and slightly girthier **Original Summary** This is an upgrade/replacement for limit switch brackets that attach to 8mm rods, commonly seen on RepRap and Prusa models. My first experiences with 3D printing were frustrating due to difficulties in getting and keeping the Z index properly adjusted. I hope this helps some people avoid problems I experienced. And for those who are beyond the beginning part of your 3D printing experience, this should make a common task easier. When I got my 3D printer, it shipped with design flaws in the Z-stop mechanism (the limit switch on the Z axis). I'm guessing mine's not the only one. The good news is that the thing with design flaws has a way of making things to fix its design flaws. So, here we go... Problem 1: Adjusting the Z index position required moving the bracket that holds the limit switch. This turned out to be very tedious, and I ended up breaking the bracket by handling it too much (specifically, by tightening it down too much - see below). A moving limit switch is not terribly useful. Problem 2: The switch could only be mounted to its bracket by one bolt, meaning it could turn freely unless I tightened it down REALLY hard. Again with the moving switch! Problem 3: The bracket was taller than the switch, so if the switch wasn't rotated in the bracket properly, the switch would never trigger and the print head would keep moving downward, pushing the entire bracket and switch with it. On more than one occasion, I had to franticly pull the power from the printer to stop the print head from pressing further into the bed. Ouch! (I later realized that I could just manually activate the switch with a finger, but when I was new and didn't know the equipment, I freaked out, OK?) Problem 4: The default stopping mechanism allowed the X axis carriage to "crash" into the switch, and unless the switch was tightened down to the printer VERY hard, it would move out of place. Yep, another "moving switch" scenario. The solution started with this thing: https://www.thingiverse.com/thing:1175592 This resolves problems 1 and 4. However, instead of using it how they picture, I super glued a nut to the top of the piece, screwed the bolt in upside-down (from the bottom-up) and added a spring to the underside of the bolt to keep downward pressure on it (see picture) and keep it from vibrating out of place. This has worked very, very well for me. Part 2 of the solution is this thing. It adds a shelf underneath the switch for support, gives enough space to use two bolts to secure the switch to the bracket and prevent it from rotating (the support shelf also reinforces that), and keeps the mechanical arm 100% above the bracket so you can't possibly "not trigger" the switch. This should work for any standard limit switch that mounts to an 8mm rod.