Astromania finder scope dovetail base screw size
M4 · length not stated in the sources
Astromania finder scope dovetail base takes M4 metric screws. None of the sources we found gives an exact length, so measure the original before you order.
The record covers dovetail mounting base uses two M4 screws for red dot / optical finderscope attachment.
This entry is marked confirmed and comes from astromaniaoptics.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.
Astromania finder scope dovetail base 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 | Dovetail mounting base uses two M4 screws for red dot / optical finderscope attachment | Confirmed |
Fitment records and sources
Dovetail mounting base uses two M4 screws for red dot / optical finderscope attachment
pitch 0.7 mm · tap 3.3 mm · clearance 4.5 mm · PH2 / Torx T20
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 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
- 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.
- Ideal Scope Mounting System manuals disagree between revisions (M4 vs M5 clamping screws) - check your own manual.
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Questions about Astromania finder scope dovetail base screws
- What size screw does Astromania finder scope dovetail base use?
- M4 for dovetail mounting base uses two M4 screws for red dot / optical finderscope attachment.
- How long are the screws in Astromania finder scope dovetail base?
- 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 Astromania finder scope dovetail base?
- 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.