What is the default fixings thread?

[choochoo_baloo]

Am I correct in saying that M6.0 (x 1.0 pitch) is the default thread for astro fixings - clam shell OTA rings, dovetail plates, etc?

[Dr_Ju_ju]

No, a lot are, but they can often be UNC threads i.e. the ones found on Camera plates etc..

[choochoo_baloo]

7 minutes ago, Dr_Ju_ju said:

No, a lot are, but they can often be UNC threads i.e. the ones found on Camera plates etc..

Thanks Julian. I assumed the former because all of my William Optics parts seem to be.

Perhaps a better question is: do you know the default thread for other big brands eg Takahashi?

[Dr_Ju_ju]

Sorry no....

[Oldfort]

Meade, Celestron and Televue typically use UNC and UNF threads.  I'd extrapoltae from that to guess that other US brands will the the same.  The rest of the world generally uses metric.  An exception is camera tripods which will use 1/4" or 3/8".

Threads on telescope heads don't seem to have a standard, other than UNC or metric.