The SC7301 is a compact 3-pin SPDT micro limit switch fitted with a sprung lever arm, rated 5A at 250VAC. It's the lever-arm switch in the popular KW11-3Z endstop family — a go-to position sensor for 3D printers, CNC machines, laser cutters and DIY automation. The lever gives smooth, low-force triggering as a cam, carriage, gantry or door sweeps past, and its three terminals (common, normally-open and normally-closed) let you wire it as either a normally-open or normally-closed trigger. A snap-action mechanism delivers a crisp, repeatable click every time.
- SPDT contacts — one common (C), one normally-open (NO) and one normally-closed (NC) terminal
- Sprung lever arm — smooth, low-force triggering as a target sweeps past
- Rated 5A at 250VAC — handles mains or low-voltage DC switching
- Snap-action mechanism for a sharp, repeatable trigger point
- Long life — rated for over 1,000,000 operating cycles
- Low contact resistance — ≤50 mΩ
- High insulation resistance — ≥100 MΩ
- Dielectric strength ≥1000VAC for 1 minute
- KW11-3Z-style body and mounting — drops into standard endstop brackets
- Ideal as a 3D printer / CNC endstop or door / limit sensor
Specifications
What's in the pack
Quantity as selected. Ready to wire — no extra components required.
Great for
Getting started
- Identify the three terminals
The pins are common (C), normally-open (NO) and normally-closed (NC). On most SC7301 / KW11-3Z bodies the centre pin is the common; check the moulded markings or test with a multimeter in continuity mode.
- Choose NO or NC
Wire C + NO for a circuit that closes (turns on) when the lever is pressed, or C + NC for one that opens (turns off) when pressed. For 3D printer / CNC endstops, NC wiring is often preferred so a broken wire reads as triggered.
- Mount the switch
Fix it through the two mounting holes so the lever arm meets your moving part right at the travel limit. Leave a little over-travel so the switch fully actuates without bottoming out.
- Test the click
Actuate the lever by hand — you should feel a firm snap and hear a distinct click as the contacts change over. Confirm the switching with a multimeter before wiring it into your machine.
Common questions
When should I choose the lever version?
The sprung lever arm is ideal where a cam, carriage, gantry or door sweeps past the switch — it gives smooth, low-force triggering and a bit of stand-off from the moving part. If your target presses the switch straight on in a tight space, the plain no-lever KW11-3Z is the better fit.
What do the three pins do?
This is an SPDT (single-pole double-throw) switch. The common terminal (C) connects to the normally-closed (NC) contact when the switch is at rest, and to the normally-open (NO) contact when pressed. You only ever use two of the three pins for a given circuit — C plus whichever of NO or NC you need.
Can I use it as a 3D printer or CNC endstop?
Yes — the SC7301 is the lever version of the hugely popular KW11-3Z endstop, used across 3D printers, CNC machines and laser cutters. Wire C + NC (or C + NO to match your board's logic) and connect to your controller's endstop input.
How much can it switch?
It's rated 5A at 250VAC, so it comfortably handles low-voltage logic signals (3.3V / 5V), DC loads and mains-voltage switching within that limit. Stay within the rating and observe normal mains-voltage safety practice when switching AC.
Good to know: Two of the three terminals are used per circuit — common (C) plus either NO or NC. For machine endstops, NC wiring is commonly preferred so a damaged wire fails safe as "triggered". The switch is rated to 5A / 250VAC; keep within that limit and follow standard mains-voltage safety practice when switching AC.