I learned on a lathe at school 30 years ago but nothing again until recently. We're all learning and I'm really no expert either. This was me trying to work it out for myself. There is a very good channel called Blondihacks that I've since discovered that may have helped me avoid some of the lathe operating pitfalls. Good luck on your journey.

@@OrdinaryWorld Discoverd Blondi also, lol. We learn from each other, wish i had more time to play around, but succesfully cut my first thread yesterday, not best looking, bit it work, guess ill get better at finished product and same wishes to you too sir!

The correct angle for imperial ( = inches ) threads is 55 degrees, and it's half is 27,5 NOT 29,5. For correct orientation of the compound i do use a little square, built from myself with the help of simple trigonometric rules ( sin and cos from a scientific calculator ). If your motor stops during threading cutting, before beginning threading operations, cut a minor diameter on your piece, where the threading will have to be ended ( for 3/4 " ... i would say ... 16,0 mm. or 15 mm. - please, make your self conversion from millimeters to inches : remember 25,4 milimeters = 1 inche ... ). That "minor diameter" should be large more than 1/10 of an inche, better 2/10 , whose value in metric system is 5,08 mm. This would help to discharge force on the tool at the end of each threading trip. ( i suggested 16,0 / 15,0 mm. , but there are specific tables on doing that, if you haven't other chance i can try to send them you later, but those of my are metric-oriented ... ) After that ( with your compound at 27,5 degrees ) you have to advance A BIT ON EVERY TRIP , in many and many "trip", for more that 2,54 mm. ( remember, your imperial threading is not an equilater triangle ); you must advance till 2,75 mm. ( from trigonometric simple rules ... ). I hope someone more expert than me can give you better instructions ... Pay attention ... your piece must be firmly tighten in the chuck, use of tail-stock is raccomended if possible. Also notice that the work made from the tool begins far an far harder when the tip advances into the piece ... ( the worst is at the end ... ) For long ( and slim ) screws to be cutted, a following rest is hardly suggested. Good luck, just in these days i have threated 2 long pieces, 3/8" - 20 TPI, long almost 300 mm. , that is the maximum allowed by my chinese mini lathe ... at least now all is ok, after 2 fail attempts ... ( experience is all ! )

Oh ya, 40 50 60 30 would prob be your best gear set.

I think to truly get a metric thread, you need a machine with a metric leadscrew. I've not looked into it but if you checkout the link in the video, it should tell you how close you can get with the imperial leadscrew and the right combination of gears. It also depends on how many threads you need engaged at the same time.

Hello, i have a metric chinese mini lathe with metric lead-screw, pitch 1,5 mm. Without changing the lead-screw, i can cut treads in inches with the following error, after having selected the right gears ( to be purchased and then worked in diameter-bore and tickness ) : 25,38461538... instead than 25,4 , that is the true value in millimiters of an inch. The error is 0,06 % , as to say 0,6 for a thousand and - unless cutting very long screws - it is generally ok. ( in addition, now i can also arrange a 127 teeth gear to get exact values, i made an extension in the gear box, whose cover has to be removed when the 127 gear is in use ). Can't this work done in reverse ? How many threads-for-inch has the imperial lead-screw of your lathe ?

Interesting. I think I considered that at one time but then you have to reverse the spindle, the feed and the tooling. Don't know any reason why it wouldn't work and it also has the advantage that you can accurately control the length of the thread.

Buy a thread cutting insert tool or grind a hunk of HSS to a 60 degree point (assuming you're doing 60 degree threads)

I had a really hard time starting the larger die, even after chamfering the end of the bar being threaded. It would probably have been a good idea to either start a short thread on the lathes or use the lathe to create a longer more gradual chamfer perhaps? This might help to get the larger dies started?

I also found this short video of where I cut the corresponding threads with the Harbor Freight large tap & die set. Not much in the way of instruction or technique though. kzfaq.info/get/bejne/nLiFnsJ2qpfbcoU.html

They come with "plastic" gears but you can buy replacements that are often metal.

Yes. You can cut in either direction and change the hand of the thread. And in fact, cutting the opposite LH thread is easier because you can start at the same point on the piece and end the cut in free air, rather than having to stop the machine halfway through the piece. Theoretically, you could also invert the cutting tool but that's not really something I'd recommend, especially with a tool post like the one on this mini lathe... but possible.

I really just went for the closest imperial equivalent to the M20 thread of the original. But you're right and in the end, I opted for a manually threaded 3/4 with 16 TPI tap & die. Still, I learned a few things in trying it out on the the lathe.

Yes, the supplied gears are plastic but surprisingly resilient. Metal sets are available too, if you feel the need.

@@OrdinaryWorld Thank you very much for the information, much success with your channel and projects.

Yes. You can buy metal replacements but I've heard very few stories of issues with the plastic.

Please don't police what I choose to do in my own workshop. Thanks.

I left the key in a completely inop Stark lathe? I bet you're fun at parties.

You mean the table on the front of the lathe shown in the video here: kzfaq.info/get/bejne/a9-RldyhmpnDYnU.html