Thread size

[Anthonyexmouth]

Anyone know the larger female thread on the SW 9x50 finder scope? I bought mine second hand with a 3d printed adapter to male m42. almost knackered the threads today and was wondering what I'd have to order if it ever broke. My calipers are reading 50.4mm

[vlaiv]

https://www.firstlightoptics.com/adapters/astro-essentials-sky-watcher-9x50-finder-to-c-adapter.html

This page suggests that 9x50 from Skywatcher is 51mm with pitch 0.75

On the other hand, it might be 2" - 32tpi? That would be 50.4mm and thread pitch of 0.79375mm

In any case, do you want metal part or 3d printed one? Both are available online for 9x50 from sky watcher (above is to C adapter, but here is T2 version: https://www.teleskop-express.de/shop/product_info.php/info/p4520_TS-Optics-T2-Adapter-for-autoguiders-to-Skywatcher-50-mm-and-30-mm--finder-scopes.html)

Or 3d printed version:

https://www.thingiverse.com/thing:3444749

(this was just a quick search).

Note that 3d printed version suggests 2" SCT connection on this finder which would be 2"-24 tpi, according to https://agenaastro.com/articles/guides/astronomy-threads-explained.html#small

 

[Anthonyexmouth]

That's fantastic, thanks. I don't need anything yet but got a little panicked when I nearly butchered the thread on my printed part. Had it nearly 6 years now and wasn't new then so lasted pretty well.