Oops…
I finally got around to making the jacking screw for a little machinist jack tonight. I found some free cutting stainless steel that comes up to a bright polish and thought it would make a good contrast to an oil blacked base.
Well it cut wonderfully, creating long single curls of swarf, nice surface finish, with a 20 thou (0.5mm cut).
But could I get an HSS M6 die to cut it? Barely. I took off a 5 thou to ease things for the die and it got worse, I had obviously really badly workhardened the surface.
So I switched over to some tougher steel, EN24T at a guess. the surface finish was awful, so I thought I’d better sharpen the tool – that’s when I noticed it was a flat topped tool for brass with zero rake. No wonder it workhardened the stainless!
Moral – don’t assume you have the right tool in the toolpost , even idf it looks right at a glance!
Neil