Thread size question

[savarin]

I have a fine thread to cut to fit into an existing threaded part.
Using my cheap thread gauges it appears to be either a 0.8 metric thread or 32G imperial thread.
With my eyesight I'm finding it difficult to say which it should be.
Can any of you imperial guru's tel me the actual difference between the two?
And just in case anyone actually knows the thread its on a telescope diagonal.

 

[MrWhoopee]

They are so close it takes quite a bit of engagement to even tell, .03125 in. vs .03149 in. What is the major diameter?

edit: https://agenaastro.com/articles/guides/miscellaneous/astronomy-threads-explained.html#specifications

 

[savarin]

32.5mm dia and only 4mm of thread engagement

 

[Tozguy]

following

 

[Technical Ted]

If they are that close it most likely won't make any difference which way you go...

Ted

 

[Tozguy]

Forgive my ignorance but is this thread for making adjustments when using the telescope or for fixing parts together?

 

[Bi11Hudson]

With a questionable thread, the first place I would look is where and when it was sourced. And whether there were any other threads that could be definitively measured.

.

 

[pdentrem]

I would suspect Metric as all my astro gear has metric threads even the stuff made in North America. Other than the 1/4 X 20 tripod mount screw!
Pierre

 

[MrWhoopee]

32.5mm dia and only 4mm of thread engagement

Well, 32.5 doesn't translate to any nominal Imperial dimension, so I'm going with metric. With only 4 threads of engagement it likely matters not. Choose whichever is native to your lathe.

 

[savarin]

My instinct was to go metric so I think thats what I will do and see what happens.
Its to screw into a 90' diagonal in place of the original fitment.
Photos when I get a round tuit