Root 3 CNC - Preparing the Endstops

Mechanical limit switches are used as my Root 3 CNC endstops.  These switches are readily available from any number of sources, see below for a link from Amazon:

10 Pcs 10x Spdt No Momentary Nc Hinge Lever Mini Micro Switches Dc Kw11 Kw12 A5

Since the components are small and prone to break over time, I spent a bit of time customizing the switches for easy replacement, and planned to install them in a "normally-closed" configuration (see NC vs NO).  For this layout, 3 wires are needed to return from the switch to the electronics shelf of the CNC: red, black, and braid/shield wire, so a 3-pin JST connector was used.  Due to the limited space, the terminal for the NO connection was removed from the switch so a capacitor could be installed easily between NC and COM.  The schematics based on this design are shown below.

The following wiring was used:
Wesbell Electroincs
CAROL-C0762
4C 22AWG FS DRAIN

The following JST connectors were used:
QLOUNI 2.54mm Pitch JST SM 2 3 4 5 Pin Male/Female Plug Kit

First the Limit Switch NO terminal was removed:

Then the capacitor, wiring and JST connector were soldered and assembled:

Finally the exposed NC and COM terminals were covered in liquid tape.  See the next post for documentation on installing the limit switches.

Root 3 CNC - Endstops Overview

Implementing endstops is where my Root 3 project was originally put on pause, so an argument could be made that I spent 18 months working them.  In reality it wasn't quite that long, but upon project restart I did spend a lot longer than I would have guessed at making the endstops behave.  Rather than trying to squeeze everything into one long post, I'll be breaking this topic up into a few component parts.

Note that everything I document is actually the second pass at building a solution.  For the first pass, I followed the standard Root 3 design and attempted to solder everything into a DB9 connector on the project control panel.  This resulted in a mess that never really worked reliably.  Apparently soldering 9 22awg wires into a DB9 connector is very tedious and prone to error if your soldering skills are rusty like mine...

Since I also wanted to run both min and max endstops for each axis in a "normally-closed" configuration, I decided to take a step back and design a different approach using DB9 breakout connectors and a breadboard soldering panel (see below).  This is completely over-engineered, but after my first DB9 soldering pass failed, I wanted to ensure success on the second pass.

CNC Endstop Panel

Electronics Cabinet Endstop Panel

Root 3 CNC - Retroactive Posts

And just like that a year and a half went by... 

One of my kids started high school, another made a travel soccer team, and before you know it all my free time had vanished and 18 months disappeared in the blink of an eye.  As unlikely as it seems, the current pandemic placing a pause on planet Earth has actually given me some much needed time to think and get back to basics.

In my limited spare time I continued on with the Root 3 build, but at a snails pace.  I'm much further along and have a number of pictures to document the steps I have not documented to date.  Sometime soon I will retroactively make posts on the other major sections of the build.

In the meantime, I'll start posting with what I'm currently working on, and hopefully in a few months it will all even out...