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Thorlabs CPMA4/M snap-on 30mm cage bracket screw size

M4 · length not stated in the sources

Our records put Thorlabs CPMA4/M snap-on 30mm cage bracket on M4 screws. None of the sources we found gives an exact length, so measure the original before you order.

The record covers bracket named for its M4 tap, mounts cage assemblies to posts.

This entry is marked confirmed and comes from thorlabs.com.

An M4 screw is 4 mm in diameter with a 0.7 mm pitch, tapped with a 3.3 mm drill; imperial look-alike: #8-32 (4.17 mm) — the standard US PC/rack screw, close but not the same.

Thorlabs CPMA4/M snap-on 30mm cage bracket 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.

ThreadLengthPitchHeadDriveWhere it goesStatus
M4not stated0.7 mmnot statednot statedBracket named for its M4 tap, mounts cage assemblies to postsConfirmed

Fitment records and sources

M4tappedconfirmed

Bracket named for its M4 tap, mounts cage assemblies to posts

pitch 0.7 mm · tap 3.3 mm · clearance 4.5 mm · PH2 / Torx T20

How to check the screw before you buy

  1. Do not confuse metric mounting screws with the 1/4-20 or 3/8-16 tripod threads that cameras and clamps also carry.
  2. Diameter: across the threads an M4 screw measures about 4 mm with calipers (usually a hair under). If yours measures noticeably more or less, it is a different thread.
  3. Pitch: 0.7 mm from one thread crest to the next (14.29 crests per centimetre). A thread pitch gauge or the pitch-gauge tool settles it in seconds.
  4. Length: measure from under the head to the tip for pan, button, wafer and cap heads; countersunk (flat) heads are measured overall.
  5. Driver: the source does not name the drive. Standard M4 heads take PH2 for Phillips and T20 for Torx, and a 3 mm hex key for socket heads; a bit that fits loosely will cam out and strip the head.
  6. Tightening: no device-specific torque is published in these records. The site's general figure for M4 is about 2.0-3.0 N·m into metal threads and 0.8-1.4 N·m into plastic bosses; snug it up and stop.

Common mix-ups with M4

  • Camera rig/cage accessories (SmallRig, Wooden Camera/Metabones) frequently mix M4 structural screws with 1/4-20 and 3/8-16 imperial mounting points on the same product — verify which specific fastener a manual is referencing before ordering replacements.
  • Dashcam mounts advertised as '1/4" M4 screw joint' have two different threads: the 1/4"-20 camera thread and a separate M4 grub screw for the ball joint — don't order the wrong one.

Pitch gauge · Screw size finder · Torque guide

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Questions about Thorlabs CPMA4/M snap-on 30mm cage bracket screws

What size screw does Thorlabs CPMA4/M snap-on 30mm cage bracket use?
M4 for bracket named for its M4 tap, mounts cage assemblies to posts.
How long are the screws in Thorlabs CPMA4/M snap-on 30mm cage bracket?
None of the sources states a length. Remove one screw and measure it from under the head to the tip (overall for a countersunk head).
What is the thread pitch of an M4 screw?
0.7 mm (coarse), which is the standard pitch for M4 machine screws; a 0.5 mm fine pitch exists but is uncommon. The tap drill is 3.3 mm and the normal clearance hole is 4.5 mm.
What screwdriver do I need for Thorlabs CPMA4/M snap-on 30mm cage bracket?
The sources do not name the drive. For M4, Phillips heads normally take PH2 and Torx heads T20; socket heads take a 3 mm hex key.
Can I use an imperial screw instead of M4?
No. Imperial look-alike: #8-32 (4.17 mm) — the standard US PC/rack screw, close but not the same. Use a true M4 screw so it does not cross-thread or strip the hole.