What size screw does Linear rail carriage block use?

M3 × 6–8 mm for attaches a toolhead plate to the sliding block.

How long are the screws in Linear rail carriage block?

The records range from 6 to 8 mm depending on the position, so match each screw to its own hole.

What is the thread pitch of an M3 screw?

0.5 mm (coarse), which is the standard pitch for M3 machine screws; a 0.35 mm fine pitch exists but is uncommon. The tap drill is 2.5 mm and the normal clearance hole is 3.4 mm.

What screwdriver do I need for Linear rail carriage block?

The sources do not name the drive. For M3, Phillips heads normally take PH1 and Torx heads T10; socket heads take a 2.5 mm hex key.

Can I use an imperial screw instead of M3?

No. Imperial look-alike: #5-40 (3.18 mm) or #4-40 — neither interchanges with M3. Use a true M3 screw so it does not cross-thread or strip the hole.

Where can I buy replacement screws for Linear rail carriage block?

TechSpareWarehouse (our own store) lists M3 x 6mm and M3 x 8mm, which match lengths in the records above.

Linear rail carriage block screw size

M3 · 6 to 8 mm long

The screws used on Linear rail carriage block are M3 in lengths from 6 to 8 mm.

It is listed for attaches a toolhead plate to the sliding block.

This entry is marked reported and comes from hiwin.us.

An M3 screw is 3 mm in diameter with a 0.5 mm pitch, tapped with a 2.5 mm drill; imperial look-alike: #5-40 (3.18 mm) or #4-40 — neither interchanges with M3.

Linear rail carriage block screw specifications

One row per fitment record. Head, drive are shown only where the source states them; pitch is the ISO coarse pitch for the thread.

Thread	Length	Pitch	Head	Drive	Where it goes	Status
M3	6–8 mm	0.5 mm	not stated	not stated	attaches a toolhead plate to the sliding block	Reported

Fitment records and sources

M36-8mmreported

attaches a toolhead plate to the sliding block

pitch 0.5 mm · tap 2.5 mm · clearance 3.4 mm · PH1 / Torx T10

Source

How to check the screw before you buy

Printer and CNC builds usually publish a bill of materials; when it lists a length, follow it, since extrusion T-nuts and motor faces have fixed thread depths.
Diameter: across the threads an M3 screw measures about 3 mm with calipers (usually a hair under). If yours measures noticeably more or less, it is a different thread.
Pitch: 0.5 mm from one thread crest to the next (20 crests per centimetre). A thread pitch gauge or the pitch-gauge tool settles it in seconds.
Length: measure from under the head to the tip for pan, button, wafer and cap heads; countersunk (flat) heads are measured overall.
The records span 6–8 mm, which means different positions take different lengths — match each hole to its own screw.
Driver: the source does not name the drive. Standard M3 heads take PH1 for Phillips and T10 for Torx, and a 2.5 mm hex key for socket heads; a bit that fits loosely will cam out and strip the head.
Tightening: no device-specific torque is published in these records. The site's general figure for M3 is about 80-130 N·cm into metal threads and 35-60 N·cm into plastic bosses; snug it up and stop.

Common mix-ups with M3

DIN-rail terminal blocks are near-universally M3 across Dinkle, TE, Omron and RND, but torque differs (0.5-0.8 Nm) — over-torquing an M3 terminal screw strips it instantly.
Terminal-block clamp screws have manufacturer-specific torque values — over-tightening cracks the block or crushes the wire.

Pitch gauge · Screw size finder · Torque guide

Buy these screws at TechSpare Warehouse

In stock and shipped from South Carolina. Our black screws are Phillips wafer head (low profile); match the head style and length to the original before you order.

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The same screw also fits

Devices whose records share a thread with Linear rail carriage block, closest length match first.

Ender 3 V3 KE cooling fan brackets also M3 × 8 mm
Carbide3D Shapeoko 5 Pro CNC router also M3 × 6 mm
FDM hotend and extruder mounts (general) also M3 × 8 mm
Arduino Uno / shield mounting holes also M3 × 6–8 mm
Voron 2.4 3D printer also M3 × 8 mm
ESP32 DevKit boards also M3 × 6–8 mm
Arduino Mega 2560 mounting holes also M3 × 6–8 mm
Ender 3 V2 hotend and hotend cover also M3 × 6–8 mm

Questions about Linear rail carriage block screws

What size screw does Linear rail carriage block use?: M3 × 6–8 mm for attaches a toolhead plate to the sliding block.
How long are the screws in Linear rail carriage block?: The records range from 6 to 8 mm depending on the position, so match each screw to its own hole.
What is the thread pitch of an M3 screw?: 0.5 mm (coarse), which is the standard pitch for M3 machine screws; a 0.35 mm fine pitch exists but is uncommon. The tap drill is 2.5 mm and the normal clearance hole is 3.4 mm.
What screwdriver do I need for Linear rail carriage block?: The sources do not name the drive. For M3, Phillips heads normally take PH1 and Torx heads T10; socket heads take a 2.5 mm hex key.
Can I use an imperial screw instead of M3?: No. Imperial look-alike: #5-40 (3.18 mm) or #4-40 — neither interchanges with M3. Use a true M3 screw so it does not cross-thread or strip the hole.
Where can I buy replacement screws for Linear rail carriage block?: TechSpareWarehouse (our own store) lists M3 x 6mm and M3 x 8mm, which match lengths in the records above.

Heads up: shipping delay