Thread size question

[Hawkeye]

As an electrician, I have many times used both #10-32 and M5 x 0.8 screws in the same application. With only 4 mm of engagement, I'd expect either to work.

 

[savarin]

cut the thread at 0.8mm

and it screwed up perfectly

 

[savarin]

Now to sort out the next part that I'm finding difficult to work out.
I need to cut a M1 thread on the outside of the above tube but I only want a raised section of it threaded say about 12mm long.
I then need to bore a tube that will also be threaded M1 to run up and down.
I'm thinking of placing an "O" ring inside the outer tube to run on the unthreaded portion of the first tube to keep the 12mm threaded section slightly restrained with a bit of friction.
If I have the dia of the 12mm long external M1 thread what dia of bore in the second tube will I need to cut the internal M1 thread so the mate correctly?
My brain appears to be non functional at present.
Both threads will most likely be 4 or 6 thread start but that shouldnt make a difference.

 

[Ken226]

cut the thread at 0.8mm
View attachment 380909
and it screwed up perfectly
View attachment 380910

Are you making optical eyepieces or is that an eyepiece adapter?

I've been interested in making eyepieces for a few years, but haven't tried it yet.

 

[savarin]

I hope the aluminium section will be taking a stainless screwed section to give a focussing unit.
Its screwed into a right angled adaptor.
I've never made any eyepieces.

 

[savarin]

The stainless tube idea didnt work so I used aluminium.
The saga of 4 start threads continues here

The Giant Binocular

Great to see you working on the Bino again Savarin !

www.hobby-machinist.com

 

[Mitch Alsup]

Are you making optical eyepieces or is that an eyepiece adapter?

The diagonal fits in the focuser of a refractor and bends the light by 90º.
The Eyepiece goes into the diagonal.