4th axis single point 'universal' threading:
This is the 800lb Gorilla, especially if you are trying to meet a spec. for thread fit. I have experimented and tried so many methods it's just ridiculous and while I have several successful 'universal' threading G-codes and Macros, including some that will cut any arbitrary tapered thread, the 'perfect' solution continues to evade.
I have tried the 'old school' 29 degree step down learned from crusty old machinists many, many moons ago. This works great for aluminum, but 'not so much' for stainless. Then 'quadrant' type cuts where the thread form is broken down into interconnected 'blocks' in the manner of an FEA mesh. 'Farming' or 'plowing' where successive vertical or horizontal rows are removed followed by a configurable number of 'spring passes'.
The two main positioning methods I have used are actual ID/OD or a 'surface start' at Z zero (or Y zero depending on where the tool is). I will provide, privately, some of the carcasses of these animals for you to dissect if you think it may be useful and of course, I am happy to discuss different methods, theories, or ideas on the best approach, but I do not have 'the' answer to this one.
It would be great to get some fresh ideas on how to skin this cat. A theory to work on. I can cut threads, no doubt, but I don't have that grin . . . you know what I mean.