Common Astro Equipment thread sizes

[Astrofriend (Lars)]

This was really interesting and useful.

When I upgraded my refractor with 2.5" flatfield flattener and later a 3" I had big problems until I got the right parts.

You can read here what threads I had to use.

2.5" ff + reducer:
http://astrofriend.eu/astronomy/proj...refractor.html

and

For the 3" ff:
http://astrofriend.eu/astronomy/proj...flattener.html

I will later upgrade the 3" ff with an off-axis adapter, then it starts all over again to find correct parts, not only the threads, they must be of the correct lenght also.

Maybe I shall collect all threads in a table later?

ps.
I think I have a 1/2" bolt to my EQ6 Synscan Pro mount, not M12, at least I bought a 1/2" recently. I will check it up later.

/Lars

[Astrofriend (Lars)]

Hi,
Now I have collected some of the threads sizes that I have come in contact with in this table:
http://astrofriend.eu/astronomy/adap...s-threads.html

I will add more of them later.

/Lars

[peterskye (Peter)]

This item was posted on the web in Sept 2018. It is fairly comprehensive.


https://agenaastro.com/astronomy-threads-explained.html


Peter Skye

[Saturnine (Jeff)]

The Agena-Astro article is , if not the definitive article, is a very comprehensive rundown on most of the thread sizes most of us are going to encounter in our astro gear.
Thanks for posting Peter.

[Wavytone]

While looking for nylon screws with knurled knobs I came across this source https://www.accu.co.uk/en/

What’s interesting is they also can make custom small parts, which I’ll try shortly.

[tempestwizz (Brian)]

I appreciate the effort that has gone into producing this thread. But did I miss something somewhere, or is it implied?
I haven’t seen included any reference to the angle of the threads, ie the thread depth.
I have acquired two sets of thread cutting tools for my lathe (internal, and external) one set is for a 65 degree and the other is for 55 degrees. I’m not sure if there are other angles used, but I have been assuming one is for metric threads and the other for imperial threads.
Maybe someone more learned than myself can confirm these parameters.

[alval (Alan)]

Hi Brian,
British imperial threads are 55 degree threads BSW and BSF etc. The other imperial ( fractional and tpi) threads used in america and elsewhere such as UNC and UNF are 60 degree threads the same as metric threads being 60 degrees.
Al

[Astrofriend (Lars)]

About metric threads, maybe this helps:

https://en.m.wikipedia.org/wiki/ISO_metric_screw_thread

Lars