Discovery DHQ 8" dob 1.25" rack-and-pinion focuser eyepiece screw screw size
M4 · length not stated in the sources
Our records put Discovery DHQ 8" dob 1.25" rack-and-pinion focuser eyepiece screw on M4 screws. None of the sources we found gives an exact length, so measure the original before you order.
Where it is used: scopeStuff database: 'Discovery DHQ 8" dob 1.25" rack and pinion focuser eyepiece screw (2) = M4'.
This entry is marked confirmed and comes from scopestuff.com.
M4 means a 4 mm nominal diameter with a 0.7 mm thread pitch. Imperial look-alike: #8-32 (4.17 mm) — the standard US PC/rack screw, close but not the same.
Discovery DHQ 8" dob 1.25" rack-and-pinion focuser eyepiece screw 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 | ScopeStuff database: 'Discovery DHQ 8" dob 1.25" rack and pinion focuser eyepiece screw (2) = M4' | Confirmed |
Fitment records and sources
M4confirmed
ScopeStuff database: 'Discovery DHQ 8" dob 1.25" rack and pinion focuser eyepiece screw (2) = M4'
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
- Some rackmount KVM switch kits pair M4x10 bracket-to-rack screws with M3.2x4.5 bracket-to-chassis screws (non-standard M3.2, not a true M3), so kits are not fully interchangeable with generic M3/M4 hardware.
- M4 and 6-32 UNC share a nominal diameter with different pitch — a classic cross-thread in US-market kits.
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Browse all 278 in Cameras & Optics →The same screw also fits
Devices whose records share a thread with Discovery DHQ 8" dob 1.25" rack-and-pinion focuser eyepiece screw, closest length match first.
- Thorlabs FBTB/M kinematic mount for 5mm cube optics also M4
- Newport M-HM-2 edge-grip filter mount also M4
- Metabones/Wooden Camera Unified BMPCC4K camera cage lens support clamp also M4
- Thorlabs ELL21/M rotation mount also M4
- Celestron NexStar 8 eyepiece holder also M4
- Optic/scope ring mounting screw manufactured to engineering drawing (fastener supplier drawing, generic optics mount hardware) also M4
- OpenFlexure Delta Stage frame also M4
- Vivotek IT9360-H / IT9380-H dome camera also M4
Questions about Discovery DHQ 8" dob 1.25" rack-and-pinion focuser eyepiece screw screws
- What size screw does Discovery DHQ 8" dob 1.25" rack-and-pinion focuser eyepiece screw use?
- M4 for scopeStuff database: 'Discovery DHQ 8" dob 1.25" rack and pinion focuser eyepiece screw (2) = M4'.
- How long are the screws in Discovery DHQ 8" dob 1.25" rack-and-pinion focuser eyepiece screw?
- 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 Discovery DHQ 8" dob 1.25" rack-and-pinion focuser eyepiece screw?
- 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.