Now SOD you have not been paying attention in the back
the blank isn't free to rotate.
A rotating rack!!!!!!!!!!!
What are you on
One out of ten for imagination
You would need a mill with a freely moving cross slide
So I would put a lead-in taper on that cutter (just like a taper tap)
That would shunt the whole job in 5 mins NOT 5 hours
I didnt get where I am by sitting in an armchair sniping at "can do" MEH 
JB – you never seen an ACME tap?
Edited By brian jones 11 on 21/09/2021 19:02:05