Telescope accessory thumb screws screw size
M3 · 12 mm long
Telescope accessory thumb screws takes M3 metric screws, 12 mm long.
It is listed for anodized accessory thumb screws explicitly sold in M3 and M4, with M3 commonly used for smaller eyepiece/accessory threads.
Head and drive, as the source states them: thumb screw (knurled) head.
This entry is marked confirmed and comes from telescopescanada.ca.
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.
Telescope accessory thumb 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 | 12 mm | 0.5 mm | Thumb screw (knurled) | not stated | Anodized accessory thumb screws explicitly sold in M3 and M4, with M3 commonly used for smaller eyepiece/accessory threads | Confirmed |
Fitment records and sources
Anodized accessory thumb screws explicitly sold in M3 and M4, with M3 commonly used for smaller eyepiece/accessory threads
pitch 0.5 mm · tap 2.5 mm · clearance 3.4 mm · PH1 / Torx T10
How to check the screw before you buy
- Do not confuse metric mounting screws with the 1/4-20 or 3/8-16 tripod threads that cameras and clamps also carry.
- 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 thumb screw (knurled) 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 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
- 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.
- GoPro's own official Dive Housing user guide does not itself state a metric screw size for the housing body; only third-party accessory manufacturer (INON) manuals explicitly cite M6 screws for their add-on arms/adapters attaching to the housing.
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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Browse all 278 in Cameras & Optics →The same screw also fits
Devices whose records share a thread with Telescope accessory thumb screws, closest length match first.
- Wooden Camera 153250 SSD Guard (RED EPIC) also M3 × 12 mm
- Celestron EdgeHD 8" OTA secondary mirror collimation screws also M3 × 12 mm
- Celestron EdgeHD 11" OTA secondary mirror collimation screws also M3 × 12 mm
- Celestron C11 Schmidt-Cassegrain OTA secondary mirror collimation screws also M3 × 12 mm
- Wimberley AP-553 lens foot plate also M3 × 12 mm
- Microscope objective turret and stage also M3 × 12 mm
- Partizan / Pilotix PT10 V3 FPV frame also M3 × 12 mm
- OpenFlexure Delta Stage also M3 × 12 mm
Questions about Telescope accessory thumb screws screws
- What size screw does Telescope accessory thumb screws use?
- M3 × 12 mm for anodized accessory thumb screws explicitly sold in M3 and M4, with M3 commonly used for smaller eyepiece/accessory threads.
- How long are the screws in Telescope accessory thumb screws?
- 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 Telescope accessory thumb 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 Telescope accessory thumb screws?
- TechSpareWarehouse (our own store) lists M3 x 12mm, which matches the length in the records above.