KW12 Micro Limit Switch TS-1D3 — 16 mm Straight Lever, 3-Pin SPDT, 5 A 250 V, Copper Contacts (10-Pack)

A micro limit switch is a small snap-action switch with a lever that changes state when a moving part touches it. The TS-1D3 (KW12 family) has SPDT copper contacts rated 5 A at 250 V, a 16 mm straight lever and three pins, so it can be wired normally-open or normally-closed without changing the part.

The plain, dependable micro limit switch that ends up in every machine you build. SPDT copper contacts rated 5 A at 250 V, a 16 mm straight lever for a generous actuation arc, and three pins so you can wire it normally-open or normally-closed without changing parts. Sold in packs of ten, because in practice you never need just one — a three-axis machine wants three for homing, and the spares live in the drawer until the next build.

What can you use it for?

• 3D printer X/Y/Z endstops and filament runout detection
• CNC router, laser and plotter axis limits and homing switches
• Robot arm and linear actuator end-of-travel protection
• Door, guard and drawer interlocks on machines and enclosures
• General DIY detection — lid open, tray present, arm at rest

Who is it for?

3D printer and CNC builders, robotics hobbyists, makerspaces and maintenance technicians who go through limit switches in quantity and want a known 5 A copper-contact part rather than the cheapest unmarked one.

Compatibility

• Controllers: Marlin, Klipper, GRBL, RepRap boards, Arduino, Raspberry Pi and PLC digital inputs
• Wiring: three pins — COM, NO and NC — so the same switch serves normally-open or normally-closed logic
• Rating: 5 A at 250 V AC; for low-voltage logic inputs add the usual pull-up or pull-down in your controller
• Lever: 16 mm straight lever; the same KW12 family also offers roller, bent and no-lever versions

Specifications

What's in the box

• 10 × TS-1D3, 16 mm straight lever, 3-pin: 10 × TS-1D3 micro limit switches

Shipping and returns

Ships from our warehouse in Singapore with tracking. Parts and accessories: free standard shipping on orders over $25 ($4.99 below) to Canada, the UK, EU, Japan, Korea, Australia and most other countries, 5–15 days; to the United States at carrier cost from $27.99 (SingPost) or $109.99 (DHL Express). Assembled robot-arm kits over 2 kg are built and calibrated to order in Singapore (dispatch in 7–10 business days) and ship worldwide at carrier cost: SingPost Speedpost Priority from $124.99 (10–14 business days) or DHL Express from $229.99 (3–5 business days), shown at checkout. 7-day returns; defective items are replaced or refunded with shipping covered. Import duties, where charged by your country, are paid by the recipient.

Frequently asked questions

How do I wire this as a normally-closed endstop?

Use the COM pin and the NC pin. The circuit is closed at rest and opens when the lever is pressed, which is the safer choice for machine limits because a broken wire also trips the limit.

Can I use these as 3D printer endstops?

Yes. They are the standard mechanical endstop type for Marlin, Klipper and GRBL machines. Wire COM and NC to your board's endstop header and set the endstop logic to match.

What is the difference between KW12 and TS-1D3?

KW12 is the family name for this small micro-switch format; TS-1D3 is the specific model — three pins with a 16 mm straight lever. They share the same body and mounting holes.

Is 5 A 250 V the real rating?

That is the contact rating for AC mains switching, with copper contacts and a CCC certificate (2020970304002085). In typical endstop use you switch only a few milliamps at 3.3–5 V, far below the rating.

Why buy ten?

A three-axis machine needs at least three for homing, and lever switches are a wear part. In practice a pack of ten covers a build plus spares.