If you want to cut metric threads, I have a "supplemental" chart to offer you. It shows how to set up for all the commonly used metric threads except 5.5mm. Three of them are approximate, but good to better than ½%. The chart on the lathe has a bunch of metric thread pitches (like 2.4mm, 0.45mm, etc.) that just aren't used with actual fasteners. Enjoy!
PS - I developed the chart for my "vintage" Grizzly DF224G, which as far as I can tell, uses the same gearing as your Jet and lots of other 12" swing lathes.