What size screw does GT2 pulley grub screws use?

M3 × 3–4 mm for locks the timing pulley onto the motor shaft.

How long are the screws in GT2 pulley grub screws?

The records range from 3 to 4 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 GT2 pulley grub screws?

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 GT2 pulley grub screws?

TechSpareWarehouse (our own store) lists M3 x 3mm and M3 x 4mm, which match lengths in the records above.

GT2 pulley grub screws screw size

M3 · 3 to 4 mm long

Our records put GT2 pulley grub screws on M3 screws in lengths from 3 to 4 mm.

Where it is used: locks the timing pulley onto the motor shaft.

This entry is marked reported and comes from vorondesign.com.

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.

GT2 pulley grub screws 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	3–4 mm	0.5 mm	not stated	not stated	locks the timing pulley onto the motor shaft	Reported

Fitment records and sources

M33-4mmreported

locks the timing pulley onto the motor shaft

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

Source

How to check the screw before you buy

Into printed plastic, the screw either self-taps or needs a heat-set insert; machine screws straight into plastic strip easily.
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 3–4 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

M3 is the most common FPV screw, but length must match arm and stack thickness — too long can short motor windings or crack frame plates.
Grub screws (set screws) on sensor retainers are frequently M3 even when the surrounding housing uses M4/M5 fasteners — don't assume one thread size for a whole enclosure.

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 GT2 pulley grub screws, closest length match first.

NEMA 23 stepper motor, 3A variant also M3 × 4 mm
NEMA 17 stepper motor faceplate also M3 × 4 mm
Bambu Lab X1/P1/AMS spare screw kit also M3 × 4 mm
GT2 timing pulley grub screws also M3 × 3–4 mm
Bondtech 17-tooth steel gear also M3 × 3 mm
Prusa i3 MK3S/MK4 printed parts and extruder also M3 × 4 mm
E3D V6 hotend fixing kit also M3 × 3–4 mm
Dell Inspiron 15 5582 2-in-1 also M3 × 3 mm

Questions about GT2 pulley grub screws screws

What size screw does GT2 pulley grub screws use?: M3 × 3–4 mm for locks the timing pulley onto the motor shaft.
How long are the screws in GT2 pulley grub screws?: The records range from 3 to 4 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 GT2 pulley grub screws?: 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 GT2 pulley grub screws?: TechSpareWarehouse (our own store) lists M3 x 3mm and M3 x 4mm, which match lengths in the records above.

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