Sunday, March 29, 2020

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.

No comments:

Post a Comment