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 long as you are going to buy or make some parts, find some pieces of
a DRO.
I got a Heidenhain scale, from eBay, and all the other parts to add a
set of scales to my lathe, for under $200. And now I can read Diameter,
yes Diameter in either .0001" or .002 mm units with the flip of a
switch.
It is Well worth every dime of the conversion!! And I never again look
at the dials.
Pete