Thorlabs SMR1/M Ø1" lens mount with SM1 internal threads screw size
M4 · length not stated in the sources
The screws used on Thorlabs SMR1/M Ø1" lens mount with SM1 internal threads are M4. None of the sources we found gives an exact length, so measure the original before you order.
It is listed for M4 tap for cage rod attachment.
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 SMR1/M Ø1" lens mount with SM1 internal threads 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 |
|---|---|---|---|---|---|---|
| M4 | not stated | 0.7 mm | not stated | not stated | M4 tap for cage rod attachment | Confirmed |
Fitment records and sources
M4 tap for cage rod attachment
pitch 0.7 mm · tap 3.3 mm · clearance 4.5 mm · PH2 / Torx T20
How to check the screw before you buy
- Camera and optics hardware often uses short screws into thin threaded plates, so check engagement before tightening fully.
- 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.
- 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.
- Length: measure from under the head to the tip for pan, button, wafer and cap heads; countersunk (flat) heads are measured overall.
- 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.
- 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.
- M4 and 6-32 UNC share a nominal diameter with different pitch — a classic cross-thread in US-market kits.
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Devices whose records share a thread with Thorlabs SMR1/M Ø1" lens mount with SM1 internal threads, closest length match first.
- SmallRig 2245 SSD Clamp for BMPCC 4K/6K cages also M4
- Thorlabs CP14/M 30mm cage plate also M4
- Underwater camera housing latch and port also M4
- Thorlabs nested rotation mounts also M4
- Thorlabs DDR25/M direct drive rotation mount also M4
- Meade 2" to 1.25" eyepiece adapter / 1.25" visual back also M4
- Tilta TA-RF-LPL adapter ring support (RED KOMODO cage) also M4
- Thorlabs KS05T/M SM05 kinematic mirror mount also M4
Questions about Thorlabs SMR1/M Ø1" lens mount with SM1 internal threads screws
- What size screw does Thorlabs SMR1/M Ø1" lens mount with SM1 internal threads use?
- M4 for M4 tap for cage rod attachment.
- How long are the screws in Thorlabs SMR1/M Ø1" lens mount with SM1 internal threads?
- 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 SMR1/M Ø1" lens mount with SM1 internal threads?
- 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.