On Sun, 16 Mar 2008 13:44:03 -0600, "Roger_N"
wrote:


"Robert Swinney" wrote in message
...
RogerN Sez: "Hey, I need to justify my CNC lathe and mill somehow!!!
:-)"

If you have to inquire about such a fundamental premise as the metallurgy
of screwdrivers, I'm not
sure you are ready for CNC yet.

Bob (still learning manual) Swinney


Since I don't know the fundamentals, would I be better off using W1, O1, A2,
D2, S7, or other steel? What difference in strenght would be obtained by
forging vs machining? What Rockwell hardness is borderline between bending
vs breaking?

Among those choices, and for the hardest practical screwdriver blade,
I'd use S-7. O-1 would be OK, but I think you'll get a better balance
between hardness and toughness with S-7. For a tougher tool at the
expense of a few points of hardness, use one of the chrome-moly alloy
steels; 4140, 4340. etc.

--
Ned Simmons