I cut my first thread last night on my 9" Hercus AR . First a bronze test run 5/8 11 TPI . It worked so I then did the same thread on 4140 3/4 x 3/4 bar for a part of a machine I'm restoring .
I was so happy I sat it on the bedside table for the night so I could keep having a look .
The cutting tool was just moving right to left which I suppose is the basic way of cutting thread like that. I managed to get the threading dial worked out as well . Just small steps with that so far.
The other way I see threads cut is to bring the tool in each step along an angle so that half of the thread angle face ( right Name ?) is cut each pass . Rather than both . Giving better finish. So I think for a 55 degree thread angle the compound moves at an angle of 27.5 degrees each pass.

Ive had a little look on YouTube but most demos there they have degrees marked on the cross slide . My Hercus just has a couple of 0 marks for 90 or 180 ? Im not in front of My lathe atm but there is no full 360 increments . I dont know if that's how I would set 27.5 If I did have it . I assume that is the way .

How do I accurately set the compound to move at 27.5 degrees if I want to try cutting the next thread that way ?

I imagine I could have a protractor on the work being held or a temporary bar held in the chuck but that still doesn't solve what I would line it up to on the compound slide . There is only the tiny side of the cutting tool ?? One of the cutting edges of the 1/4" HSS.

Rob


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