On Tue, 12 Mar 2013 07:20:13 -0500, Karl Townsend
wrote:

On Mon, 11 Mar 2013 12:24:16 -0700, Gunner
wrote:

On Mon, 11 Mar 2013 13:08:35 -0500, Tim Wescott
wrote:

So I'm fabricating some stuff out of 40 mil 304 sheet ('cause that's what
I could get from McMaster -- I know now it was a Bad Choice for doing
lots of drilling and whatnot).

Thanks to some input here, I'm doing pretty good, but I noticed that the
sheet seems to be fairly well annealed on one side, but really hard on
the other. Trying to drill 1/16" holes in the stuff, it makes an
enormous difference (like, between success and failure with a side of
broken drill bit) whether I start drilling on the "good" side or the
"bad" side.

Is this common?

Yes unfortunately.

And always remember

"303, thats for me!"
304..shes a whore!"

Gunner

My version

303, she's so sweet
Take her home for mom to meet
304 she's a whore
don't want to see her no more


I hadn't notice this, harder on one side, I'll keep it in mind.

I won't even try 304 drilling unless its in my big drill press.
I push so hard, I've snapped small drills from the pressure
Then use oil and run slow.

One of the biggest tricks i learned is to friction saw the stuff, run
the bad blade somkin' fast and burn your way through. i bought
friction blades, old worn blades would work about as well. I'd even
put them in backwards.

Karl

If there's any play in your smaller drill press, it may not have
enough positive feed to reliably drill stainless. While you're taking
up slack and spring, the bit is work-hardening the material.

BTW, I've never heard of the two-side differential in hardness,
either, but my limited experience in drilling 300 Series stainless is
mostly with chucked pieces of barstock, not sheet.

--
Ed Huntress