OT metric threads

[earlgo]

I've only cut one metric thread that I remember and it was a M16x2 on a mill drawbar because I bought a #40 tool holder not thinking about the knob thread.
However, on the no-qc-change-your-own-gears Atlas, it was no different than a 5/8-11, except it needed a different gear combination. I don't remember doing anything special in relation to engaging the half nuts, and I always use the '1' on the thread dial so I don't have to remember odd, even, or divisible by 8.

The Manual of Lathe Operation and Machinists Tables that came with the Atlas lathe lists 97 combinations to cut inch threads from 1.25 to 79 tpi, 16 metric from .5 to 7.0 mm pitch and 6 carriage feeds from .0016 to .0085 ipr. Flexible but a bit inconvenient.
(If anyone needs the list, pm me, and I will send a copy.)

--earlgo

[liveaboard]

I don't have one of those fancy thread dial thingies...
I don't cut a lot of threads, but when I do I reverse it out; my motor has 2 speeds so sometimes I reverse a bit faster.
Many people have variable frequency drives these days, so it would be pretty easy to set up a slow cut/ fast reverse.

[tornitore45]

While that works on principle, pencil mark on oily ways?

I was wrong, I tried a pencil mark on a oily way and it was perfectly legible.

[dly31]

While that works on principle, pencil mark on oily ways?

I was wrong, I tried a pencil mark on a oily way and it was perfectly legible.

If you have a thread dial it can also be used to catch the right point on the leadscrew as long as the carriage is within one revolution of the dial of the right spot. One dial revolution is typically 1, 2, or 4 inches. You just have to use the same number that was lined up before you opened the half nuts.

[SteveHGraham]

There used to be a crazy guy on the forum who couldn't make metric threads on his Bronze Age Clausing (inspection sheet signed by Archimedes), so he went nuts and bought a brand new lathe from Asia. Which was, of course, a piece of junk with Bondo making up most of the base. No one has actually checked this, but it was from Asia, so we can assume it to be true.