Thanks for the support.
The first a lot of patience, I let a screw fall out of my hands six times.
I often take the lock apart and try it on.
I started with a grinder and big files.
I bought a cheap set of files, which are very sharp.
For the rest I use 180 grit emery cloth and tear strips to size.
It rubs with all the curves.
I sand all the metal with sanding belt 180 emery cloh then waterproof 800 then 2000.
Drilling the tap hole is 1.2 mm taps 1.4 mm and 1.5 mm for penetration.
Previously I made the springs from car spring leaves, later I emailed a spring company for some metal I couldn't buy. but I got two pieces of metal
this is so soft and works so nicely of course hardening and tempering.
