Trig Avionics TT31 Mode S transponder screw size
M3 · 12 mm long
The screws used on Trig Avionics TT31 Mode S transponder are M3, 12 mm long.
It is listed for mounting tray secured with four Pozidriv pan-head screws plus self-locking nuts.
Head and drive, as the source states them: pan head and Pozidriv drive.
This entry is marked confirmed and comes from trig-avionics.com.
M3 means a 3 mm nominal diameter with a 0.5 mm thread pitch. Imperial look-alike: #5-40 (3.18 mm) or #4-40 — neither interchanges with M3.
Trig Avionics TT31 Mode S transponder 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 | 12 mm | 0.5 mm | Pan head | Pozidriv | Mounting tray secured with four Pozidriv pan-head screws plus self-locking nuts | Confirmed |
Fitment records and sources
Mounting tray secured with four Pozidriv pan-head screws plus self-locking nuts
pitch 0.5 mm · tap 2.5 mm · clearance 3.4 mm · PH1 / Torx T10
How to check the screw before you buy
- Take one original screw out first and measure it before ordering; the record above tells you the thread, the original screw tells you the exact length and head.
- 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: for pan head screws, measure from under the head to the tip (countersunk heads are the exception: they are measured overall).
- The record states 12 mm. Going longer risks bottoming out or touching parts behind the hole; going shorter loses thread engagement.
- Driver: the source names a Pozidriv drive. For comparison, standard M3 heads take PH1 (Phillips) or T10 (Torx), or a 2.5 mm hex key.
- 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
- 2020 extrusion T-nuts come in M3/M4/M5 and are not interchangeable — M3 is accessory-only, M5 is structural.
- Museum/AV projector mounting kits typically bundle four to six thread sizes (M3–M6) in one bag to fit varied projector OEM patterns — always match the specific length/thread pair actually used for a given projector model rather than assuming all sizes apply universally.
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.
-
M3 x 12mm Phillips Wafer Head Screw for Camera Cage & Battery Slide Mount - Pack of 50 Black
$6.49 -
M3 x 12mm Phillips Wafer Head Screw for Electric Scooter LCD Dashboard - Single Replacement Black
$0.10 each · min. 50
-
M3 x 12mm Phillips Wafer Head Screw for RC Car/Truck Chassis Mount - Single Replacement Black
$0.10 each · min. 50
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Devices whose records share a thread with Trig Avionics TT31 Mode S transponder, closest length match first.
- Kern PFB precision balance internal hardware also M3 × 12 mm
- 2020 aluminium extrusion T-nuts also M3 × 12 mm
- Pumpkin SUPERNOVA 6U CubeSat Structure Kit also M3 × 12 mm
- E-scooter stem and controller housing also M3 × 12 mm
- Keystone metric hex PCB standoff also M3 × 12 mm
- Milwaukee M18/M12 charger and cordless tool internals also M3 × 12 mm
- Celestron EdgeHD 11" OTA secondary mirror collimation screws also M3 × 12 mm
- FPV flight controller stack 30.5x30.5mm also M3 × 12 mm
Questions about Trig Avionics TT31 Mode S transponder screws
- What size screw does Trig Avionics TT31 Mode S transponder use?
- M3 × 12 mm for mounting tray secured with four Pozidriv pan-head screws plus self-locking nuts.
- How long are the screws in Trig Avionics TT31 Mode S transponder?
- The record gives 12 mm. Measure the original from under the head (overall for a countersunk head) to confirm before ordering.
- 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 Trig Avionics TT31 Mode S transponder?
- The source lists a Pozidriv drive. Standard M3 heads otherwise take PH1 (Phillips) or T10 (Torx), or 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 Trig Avionics TT31 Mode S transponder?
- TechSpareWarehouse (our own store) lists M3 x 12mm, which matches the length in the records above.