What size screw does RC brushless motor mounts use?

M3 × 8–16 mm for motor-to-mount screws on planes and multirotors.

How long are the screws in RC brushless motor mounts?

The records range from 8 to 16 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 RC brushless motor mounts?

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 RC brushless motor mounts?

TechSpareWarehouse (our own store) lists M3 x 8mm, M3 x 10mm and M3 x 12mm, which match lengths in the records above.

RC brushless motor mounts screw size

M3 · 8 to 16 mm long

Our records put RC brushless motor mounts on M3 screws in lengths from 8 to 16 mm.

Where it is used: motor-to-mount screws on planes and multirotors.

This entry is marked reported.

For reference, M3 is 3 mm across the threads at 0.5 mm pitch. The imperial size people confuse it with: #5-40 (3.18 mm) or #4-40 — neither interchanges with M3.

RC brushless motor mounts 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	8–16 mm	0.5 mm	not stated	not stated	Motor-to-mount screws on planes and multirotors	Reported

Fitment records and sources

M38-16mmreported

Motor-to-mount screws on planes and multirotors

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

How to check the screw before you buy

Frame and motor screws must not reach the motor windings; check the length against the motor's mounting depth.
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 8–16 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

On FPV motors, screw length is safety-critical: one turn too long and the screw crushes the motor windings. Measure arm + base depth, and dry-fit before powering up.
Telescope thumbscrews are sold in a wide non-metric legacy range too (1/4-20, 8-32, 10-32 on many Meade/Celestron mounts), so metric M3/M4 fitment applies mainly to newer/international accessory ecosystems (SkyWatcher, generic 1.25" accessories) and should not be assumed universal.

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 RC brushless motor mounts, closest length match first.

FPV drone motors (5-inch class) also M3 × 8 mm
FPV flight controller stack 30.5x30.5mm also M3 × 8–16 mm
ALware Quad Flyer Spider 500 quadcopter kit also M3 × 8 mm
TBS Source One V3 / HD FPV frame also M3 × 8–16 mm
DJI Agras Agras T50/T25/T16/T20/T30 and FlyCart 30 airframe screw also M3 × 8 mm
REV Robotics T-slot extrusion screw (41-1907) also M3 × 8 mm
5-inch brushless motor to arm also M3 × 8 mm
Nerf blaster thumbscrews (mid sizes) also M3 × 8–16 mm

Questions about RC brushless motor mounts screws

What size screw does RC brushless motor mounts use?: M3 × 8–16 mm for motor-to-mount screws on planes and multirotors.
How long are the screws in RC brushless motor mounts?: The records range from 8 to 16 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 RC brushless motor mounts?: 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 RC brushless motor mounts?: TechSpareWarehouse (our own store) lists M3 x 8mm, M3 x 10mm and M3 x 12mm, which match lengths in the records above.

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