Stealth Pilot wrote:

I have a much loved old hercus lathe that has an imperial thread
cross slide. (for the americans the lathe is a clone of a south bend)

current thread is 7/16" 10tpi left hand acme thread.
what is the best metric equivalent for a robust cross slide thread?
is the acme threadform the best for a leadscrew?

I have only used a cross slide that worked in metric once for 10
minutes and I was amazed at how much faster the work proceeded when
the cross slide was actually marked in the dimension system you are
using.

note that I'm not seeking theoretical information just practical
experiences on what works best.

Stealth Pilot
Australia

As you are aware, the Hercus is a licenced copy of a South Bend. So is
a Boxford.

If you were to dig around a bit online, I expect you will be able to
find the metric conversion parts for one of these, or at least the specs
for same. I know that there were a lot of metric SB and Boxford lathes
bought into the school shop system here in Canada, so they were out
there.
I am thinking that the parts are likely interchangeable or would be so
with very minor adaptation.

Probably want a 2 mm pitch.

Cheers
Trevor Jones