Micro servo horn/arm screw screw size
M2 · 4 mm long
Micro servo horn/arm screw takes M2 metric screws, 4 mm long.
Where it is used: M2 x 4mm is the ideal screw specification for attaching servo horn to SG90 mini servos.
This entry is marked confirmed and comes from aliexpress.com.
M2 means a 2 mm nominal diameter with a 0.4 mm thread pitch. Imperial look-alike: #2-56 UNC (2.18 mm) is close but not interchangeable.
Micro servo horn/arm screw 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 |
|---|---|---|---|---|---|---|
| M2 | 4 mm | 0.4 mm | not stated | not stated | M2 x 4mm is the ideal screw specification for attaching servo horn to SG90 mini servos | Confirmed |
Fitment records and sources
M2 x 4mm is the ideal screw specification for attaching servo horn to SG90 mini servos
pitch 0.4 mm · tap 1.6 mm · clearance 2.4 mm · PH0 / Torx T6
How to check the screw before you buy
- If several screws hold the same part, check that they are all the same length before assuming they are.
- Diameter: across the threads an M2 screw measures about 2 mm with calipers (usually a hair under). If yours measures noticeably more or less, it is a different thread.
- Pitch: 0.4 mm from one thread crest to the next (25 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 record states 4 mm. Going longer risks bottoming out or touching parts behind the hole; going shorter loses thread engagement.
- Driver: the source does not name the drive. Standard M2 heads take PH0 for Phillips and T6 for Torx, and a 1.5 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 M2 is about 25-40 N·cm into metal threads and 12-20 N·cm into plastic bosses; snug it up and stop.
Common mix-ups with M2
- Tamiya Mini 4WD parts are labelled plainly as '2mm' rather than M2; resellers add the M2 label themselves.
- M2 (2.00mm, 0.4mm pitch) is NOT the same as #2-56 UNC (2.18mm) — close enough to cross-thread and strip if forced.
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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Devices whose records share a thread with Micro servo horn/arm screw, closest length match first.
- Medtronic 670G insulin pump battery door/case screws also M2 × 4 mm
- M.2 (NGFF) SSD module retention also M2 × 4 mm
- DIN 912 socket-head cap screw also M2 × 4 mm
- DIN 965 / ISO 7046 countersunk Phillips screw also M2 × 4 mm
- HP OmniBook XT1500 also M2 × 4 mm
- Acer TravelMate 8571 also M2 × 4 mm
- HP ProBook 4510s also M2 × 4 mm
- M.2 heatsink / shield assemblies also M2 × 4 mm
Questions about Micro servo horn/arm screw screws
- What size screw does Micro servo horn/arm screw use?
- M2 × 4 mm for M2 x 4mm is the ideal screw specification for attaching servo horn to SG90 mini servos.
- How long are the screws in Micro servo horn/arm screw?
- The record gives 4 mm. Measure the original from under the head (overall for a countersunk head) to confirm before ordering.
- What is the thread pitch of an M2 screw?
- 0.4 mm (coarse), which is the standard pitch for M2 machine screws; a 0.25 mm fine pitch exists but is uncommon. The tap drill is 1.6 mm and the normal clearance hole is 2.4 mm.
- What screwdriver do I need for Micro servo horn/arm screw?
- The sources do not name the drive. For M2, Phillips heads normally take PH0 and Torx heads T6; socket heads take a 1.5 mm hex key.
- Can I use an imperial screw instead of M2?
- No. Imperial look-alike: #2-56 UNC (2.18 mm) is close but not interchangeable. Use a true M2 screw so it does not cross-thread or strip the hole.
- Where can I buy replacement screws for Micro servo horn/arm screw?
- TechSpareWarehouse (our own store) lists M2 x 4mm, which matches the length in the records above.