Micro Switch with Roller Lever (3-Terminal: COM / NO / NC)
This micro switch with roller lever is a go-to part for limit switching and position detection in robotics, 3D printers, CNC, and DIY automation. The roller lever makes it easier to trigger smoothly with moving parts, while the 3 terminals (COM/NO/NC) let you choose normally-open or normally-closed behavior depending on your design.
Why this switch is useful
- Roller lever = smooth triggering, less wear on moving parts
- 3 terminals = flexible wiring (COM + NO or COM + NC)
- Fast snap action = reliable switching
- Great as a limit switch / endstop for mechanical movement
What you can build
- Robot arm “home” position sensor
- Sliding door / drawer end-limit stop
- Conveyor end detection
- 3D printer / CNC axis endstop
- DIY safety cutoff switch (mechanical trigger)
Tip: For microcontroller inputs, pair it with pull-up / pull-down resistors (or enable internal pull-ups) for stable reads.
Understanding the 3 terminals (COM / NO / NC)
- COM = common terminal (main contact)
- NO (Normally Open) = open when not pressed, closes when pressed
- NC (Normally Closed) = closed when not pressed, opens when pressed
Quick wiring:
• Use COM + NO if you want the signal to activate only when pressed.
• Use COM + NC if you want a “fail-safe” style input (common for endstops).
Technical specifications
| Switch type | Micro switch, snap-action with roller lever |
|---|---|
| Terminals | 3 terminals: COM / NO / NC |
| Operation | Momentary (returns when released) |
| Typical use | Limit switch / endstop / position detection |
Learn the basics: What is a microswitch? • NO vs NC explained
Shop related parts: Switches collection • Robotics collection • 3D Printer Parts collection
What’s in the box
- 1× Micro Switch with Roller Lever (3-terminal)
Frequently Asked Questions
Quick answers for wiring (NO/NC), mounting, and microcontroller use.
What’s the difference between NO and NC?
NO (Normally Open) is open when not pressed and closes when pressed.
NC (Normally Closed) is closed when not pressed and opens when pressed.
For endstops, many makers prefer NC because it can be more “fail-safe” (a broken wire looks like a trigger).
How do I wire it to Arduino / ESP32?
Use COM + NO (or COM + NC) to your input circuit. For clean readings, enable your board’s internal pull-up (common approach) or use an external resistor.
Can I use this as a 3D printer endstop?
Yes. This is commonly used as a mechanical endstop / limit switch. Mount it so the roller lever gets pressed reliably at the end of travel.
Can this switch mains AC directly?
It depends on the rating printed on your specific switch. For mains and higher current loads, use proper enclosures, correct wire gauge, and consider a relay/contactor setup for safer switching.
Switch Micro with Roller Lever 3 Terminal
Switch Micro with Roller Lever 3 Terminal
59 in stock
Product Code
SKU:AL049
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