A micro limit switch is a small switch that clicks over when something presses its lever, so a controller knows a moving part has reached a set point. This KW11-3Z has a steel lever with a red roller wheel on the end, so a carriage, cam or sliding part rolls onto it instead of scraping across it. It has three pins, common, normally open and normally closed, so you can wire it to read either pressed or released.
Use it as an endstop on a 3D printer or CNC axis, a home switch in an Arduino or ESP32 stepper project, or to sense when a lid, door or drawer closes. It connects straight to 3.3V and 5V board inputs with no extra parts, and mounts with two M2 screws. Connect it with female spade connectors pushed onto the tabs, or solder the wires straight on, hooking each one through the hole in its tab. The same switch also comes as the SC7301 with a plain lever, the KW11-3Z with no lever and a 2-pin normally open lever switch.
Specifications
Datasheets
Wiring & getting started
- Find the pins
Hold the switch with the numbered face towards you and the lever pivot on the left. The tabs are 1 (COM) at the pivot end, 3 (NO) in the middle and 2 (NC) at the far end. The back face is marked C, NO and NC to match.
- Wire it
For an endstop, wire COM to GND and NC to the endstop signal pin where your board allows it. A broken or unplugged wire then reads as pressed, so the axis stops instead of running into the frame. On an Arduino or ESP32, wire COM to GND and NO to an input pin. No resistor is needed, because the board has one built in that the code switches on (INPUT_PULLUP in Arduino).
- Mount it so the part rolls on
Fix it with two M2 screws so the moving part rolls onto the wheel along the lever, not straight into the end of it. Leave a little travel past the click so the part never jams against the body.
- Check it works
Before anything moves, press the roller by hand. You should hear a click, and on a Marlin printer the M119 command should show that endstop change from open to TRIGGERED. On an Arduino with NO wired, the input reads LOW while the roller is pressed and HIGH when it is released. If it reads the wrong way round, move the signal wire to the other outer tab.
Note: For mains wiring, fit the switch inside an enclosure and have a licensed electrician do the work.