Telescope knurled locking/tension screw for diagonals, adapters, focusers screw size
M4 · 10.5 to 17.5 mm long
If you are replacing a screw on Telescope knurled locking/tension screw for diagonals, adapters, focusers, the thread is M4 in lengths from 10.5 to 17.5 mm.
The record covers 'TS-Optics Knurled M4 Screw... fits many Diagonals, Adapter and Focuser. Length of the M4 thread: 10.5 mm Length of the screw: 17.5 mm'.
Head and drive, as the source states them: thumb screw (knurled) head.
This entry is marked confirmed and comes from teleskop-express.de.
For reference, M4 is 4 mm across the threads at 0.7 mm pitch. The imperial size people confuse it with: #8-32 (4.17 mm) — the standard US PC/rack screw, close but not the same.
Telescope knurled locking/tension screw for diagonals, adapters, focusers 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 | 10.5–17.5 mm | 0.7 mm | Thumb screw (knurled) | not stated | 'TS-Optics Knurled M4 Screw... fits many Diagonals, Adapter and Focuser. Length of the M4 thread: 10.5 mm Length of the screw: 17.5 mm' | Confirmed |
Fitment records and sources
'TS-Optics Knurled M4 Screw... fits many Diagonals, Adapter and Focuser. Length of the M4 thread: 10.5 mm Length of the screw: 17.5 mm'
pitch 0.7 mm · tap 3.3 mm · clearance 4.5 mm · PH2 / Torx T20
How to check the screw before you buy
- For a wall or arm mount, the screw has to engage the threaded insert by several turns but must not bottom out, so measure the insert depth and add the thickness of the bracket and any spacers.
- 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: for thumb screw (knurled) screws, measure from under the head to the tip (countersunk heads are the exception: they are measured overall).
- The records span 10.5–17.5 mm, which means different positions take different lengths — match each hole to its own screw.
- 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
- Display mounts mix systems: the screen side is metric M4/M6, but the wall side of many mounts uses imperial wood screws such as #14 x 2.5in.
- Not all telescope/finder hardware is metric — Celestron Edge/NexStar SE finder-shoe and dovetail screws are reported as 8/32 (imperial UNC), so metric M4/M5 fitments cannot be assumed across all Celestron products; must check per accessory/vintage.
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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More in Displays, TVs & Mounts
The same screw also fits
Devices whose records share a thread with Telescope knurled locking/tension screw for diagonals, adapters, focusers, closest length match first.
- LG 60PZ950U also M4 × 12 mm
- Datex-Ohmeda Aestiva/7900 ventilator VESA mounting bracket also M4 × 16 mm
- Samsung PC490-ZA TV stand also M4 × 10.5–12 mm
- CCTV dome camera adaptor plate also M4 × 15 mm
- LG 55LW9500 also M4 × 12 mm
- Bosch Smart System 1-arm handlebar support (shell and clamp mounting) also M4 × 12 mm
- Premier Mounts PBL-UMS/PBL-UMW Universal Projector Mount also M4 × 12 mm
- Raymarine Alpha Series Display Mast Bracket also M4 × 14 mm
Questions about Telescope knurled locking/tension screw for diagonals, adapters, focusers screws
- What size screw does Telescope knurled locking/tension screw for diagonals, adapters, focusers use?
- M4 × 10.5–17.5 mm for 'TS-Optics Knurled M4 Screw... fits many Diagonals, Adapter and Focuser. Length of the M4 thread: 10.5 mm Length of the screw: 17.5 mm'.
- How long are the screws in Telescope knurled locking/tension screw for diagonals, adapters, focusers?
- The records range from 10.5 to 17.5 mm depending on the position, so match each screw to its own hole.
- 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 Telescope knurled locking/tension screw for diagonals, adapters, focusers?
- 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.