You should have 3 to 5x pitch lead as that will provide time for the acceleration of the Z axis when threading.
Always run the Calc number of passes as that will tell you if you are exceeding Accel of the axis.

I was referring earlier to the infeed angle that I had set it to 0 on that thread, I normally start my threads 20mm before it starts cutting as With the one above.

NOTE:
Threading results are only as good as:
- YOUR   "Lathe System" , you have backlash and that is not good.......
- Set up
- etc.

I totally agree, you can only do with what you have, in saying that I thought my backlash at 0.09mm was not that bad that’s only 3 thou (0.003"), and with backlash compensation turned on the machine is good to +/- 0.025mm (0.001") measuring with a dial gauge.

No device is going to  cure any bad of the above . If you think a system is good then test by doing a 0-80 thread. Then try multi start threads and see if you can do a 2 or 3  start thread.

Again agree 100%, I will have a go at 0-80 thread just for the hell of it, it should be an interesting test, what material should I use? I wouldn’t even know where to start with multi point threading, have not gotten that far yet, need a lot more reading and studying to figure that one out.

I did a little testing and cut a couple of 1" BSP threads in a piece of scrap galvanised pipe, also made a mop handle end piece from some aluminium and turned a 15/16-20 thread in that to thread the mop head on, why I just happen to have the same tap here and it fitted snugly in the mop(thats the only reason why), it also gave me something to compare the threads to. All three pieces came out quite well. I think my biggest problem was simply my setup in Mach the one that stands out the most was the debounce interval and index my initial settings where simply 1 for both, I still think I may have a little noise problem or some iffy joints in my PP cables as I made those to suite, but the SS system should fix that I hope. Hoping by the end of the week I will have the new SS system on and the burnt out power supply repaired, I am looking forward to seeing if it improves or not.