Celestron C5 Schmidt-Cassegrain OTA secondary mirror collimation screws screw size
M3 · 10 mm long
Our records put Celestron C5 Schmidt-Cassegrain OTA secondary mirror collimation screws on M3 screws, 10 mm long.
The record covers celestron's official knowledge base lists collimation screw thread as M3 x 0.5, 10mm, for the C5 optical tube.
This entry is marked confirmed and comes from celestron.com.
M3 means a 3 mm nominal diameter with a 0.5 mm thread pitch. Imperial look-alike: #5-40 (3.18 mm) or #4-40 — neither interchanges with M3.
Celestron C5 Schmidt-Cassegrain OTA secondary mirror collimation screws 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 |
|---|---|---|---|---|---|---|
| M3 | 10 mm | 0.5 mm | not stated | not stated | Celestron's official knowledge base lists collimation screw thread as M3 x 0.5, 10mm, for the C5 optical tube | Confirmed |
Fitment records and sources
Celestron's official knowledge base lists collimation screw thread as M3 x 0.5, 10mm, for the C5 optical tube.
pitch 0.5 mm · tap 2.5 mm · clearance 3.4 mm · PH1 / Torx T10
How to check the screw before you buy
- VESA holes are threaded inserts in the back cover; if a screw stops early, back it out rather than forcing it, because a bottomed-out screw can crack the panel housing.
- Diameter: across the threads an M3 screw measures about 3 mm with calipers (usually a hair under). If yours measures noticeably more or less, it is a different thread.
- Pitch: 0.5 mm from one thread crest to the next (20 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.
- The record states 10 mm. Going longer risks bottoming out or touching parts behind the hole; going shorter loses thread engagement.
- Driver: the source does not name the drive. Standard M3 heads take PH1 for Phillips and T10 for Torx, and a 2.5 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 M3 is about 80-130 N·cm into metal threads and 35-60 N·cm into plastic bosses; snug it up and stop.
Common mix-ups with M3
- Telescope thumbscrews are sold in a wide non-metric legacy range too (1/4-20, 8-32, 10-32 on many Meade/Celestron mounts), so metric M3/M4 fitment applies mainly to newer/international accessory ecosystems (SkyWatcher, generic 1.25" accessories) and should not be assumed universal.
- PC cases mix M3 (fans, optical and 2.5in drives) with imperial 6-32 (3.5in drives, motherboard standoffs) - don't force one into the other.
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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M3 x 10mm Phillips Wafer Head Screw for 3D Printer Frame Assembly - Single Replacement Black
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Devices whose records share a thread with Celestron C5 Schmidt-Cassegrain OTA secondary mirror collimation screws, closest length match first.
- LED drivers & furniture electronics also M3 × 10 mm
- Studio monitor panels also M3 × 10 mm
- Camera cage cold shoe / accessory arm also M3 × 10 mm
- Dell S2715H also M3 × 10 mm
- Soundbar drivers and boards also M3 × 10 mm
- Apple HomePod internal drivers also M3 × 10 mm
- Illuminated sign PCB standoffs also M3 × 10 mm
- Wooden Camera Director's Monitor Cage v2/v3 also M3 × 10 mm
Questions about Celestron C5 Schmidt-Cassegrain OTA secondary mirror collimation screws screws
- What size screw does Celestron C5 Schmidt-Cassegrain OTA secondary mirror collimation screws use?
- M3 × 10 mm for celestron's official knowledge base lists collimation screw thread as M3 x 0.5, 10mm, for the C5 optical tube.
- How long are the screws in Celestron C5 Schmidt-Cassegrain OTA secondary mirror collimation screws?
- The record gives 10 mm. Measure the original from under the head (overall for a countersunk head) to confirm before ordering.
- What is the thread pitch of an M3 screw?
- 0.5 mm (coarse), which is the standard pitch for M3 machine screws; a 0.35 mm fine pitch exists but is uncommon. The tap drill is 2.5 mm and the normal clearance hole is 3.4 mm.
- What screwdriver do I need for Celestron C5 Schmidt-Cassegrain OTA secondary mirror collimation screws?
- The sources do not name the drive. For M3, Phillips heads normally take PH1 and Torx heads T10; socket heads take a 2.5 mm hex key.
- Can I use an imperial screw instead of M3?
- No. Imperial look-alike: #5-40 (3.18 mm) or #4-40 — neither interchanges with M3. Use a true M3 screw so it does not cross-thread or strip the hole.
- Where can I buy replacement screws for Celestron C5 Schmidt-Cassegrain OTA secondary mirror collimation screws?
- TechSpareWarehouse (our own store) lists M3 x 10mm, which matches the length in the records above.