"Bob La Londe" fired this volley in
:

I've got a piece of mystery steel about 2' x 6' x .78". It was given
to me by a friend when he was moving. I have a couple projects for it
that are going to require machining. What would be the best guess for
the alloy to machine conservatively but without killing cutters? A36?
1018?

Man! Bob, that's a honkin' beeg chunka metal for a small shop guy!

Bob, inspect it fully before guessin'. Can you scratch it easily with hand
tools? Is the surface perfectly smooth (ground) or does it look rolled.
Was it sawn off the mother stock, or does it show a shearing snipe on one
end.

Does it possess any gray mill scale on the surface, or is the surface
completely clean and rusting? Does it rust?

Pick and edge, and just start to drill a hole with a 3/16" bit. If it cuts
nicely with a little oil, you can consider it plain A36 hot-rolled, even if
it is 1018 really. 1018 machines a bit more easily than A36, so if you go
with the recommended feeds-n-speeds for A36, you'll be safe.

Both alloys can be had in ground flats, but that's expensive and unusual to
find in pieces that wide. Now... if it's ground, doesn't rust much, and is
hard to mark/drill... you're on your own! G

LLoyd