This lathe is advertised as being able to cut english and metric threads. I have had no problems making english threads.
According to the manual, in order to do metric threads you must do the following:
Change gears - i.e. for a 1.5mm thread, select the two 48 teeth gears and run one on the 120 main gear and run the lower on the 127 gear (machine has 120/127 double main gear for converting to metric).
Select the proper combination of levers - i.e L,T,A,C according to the chart printed on the front of the lathe.
Disengage feed selector to the "O" posotion.
Now, when cutting english you use the dial indicator and engage/disengage the half-nut lever. On metric, the manual says to engage the half-nut lever and leave it engaged during the whole process of cutting the thread.
However, the manual fails to tell you how to stop the machine at the end of the cut so that you can reset the depth on the cross-feed. You cannot reverse the direction of lead screw travel as suggested by an authorized jet technician for three reasons. One, there's a large warning on the front of the machine telling you not to do this. Two, it doesn't work since you are temporarily changing gear teeth when moving the selector know, therefore you are off when reversing and coming back into the cut. Third, changing the lead screw direction goes from cutting right-handed to left-handed threads when changing directions.
It seems that the procedure involves leaving all gears continually engaged. Then you cut the forward/reverse lever on the apron section to the neutral position to cut power to the travel. The head continues to rotate due to momentum until it comes to a rest and the magnetic latches release on the motor. Then you back out the cross feed, jog the machine backwards using the jog button, reset your depth and do another cut. This appears to work, but what do you do to stop the drift after stopping? If you need to thread a half inch piece that has a 1/4" relief and then projects into a 60 degree bevel towards the chuck, you risk crashing the tool into the part when trying to guess where the momentum will stop the carriage. This machine does not come with a brake and jogging the machine backwards immediately after disengaging the feed start lever does not work since the motor does not disengage the latches until it comes to a complete stop.
I have read other scenarios about reversing with other machines, but this is designed to run 220V single phase. Any help would be appreciated.