Neotech,
That is what I am trying to work out. But he (apparently) says not.
If the tool in the picture is the right way up, and the lathe is turning in the conventional direction, then it wouldn't cut. So the tool has to be upside down.
But he writes,
.. turning the male and female threads using the lathe in the same orientation and direction on both cuts I was producing one right hand thread and one left hand thread ..
This and,
...I had the lead screw engaged in revers so I could arrange the cutter on the far side of the internal thread ...
If this means driving the saddle back towards the tailstock it would need the chuck to be turning clockwise (backwards to normal) viewed from the front. This could unscrew it.
Very confusing.
Dave.
...