At 09:23 PM 6/11/2013, Jeremy Stovin wrote:
>Why can I not get a screw or drill in this floor? It just stops.
>Metal, self tapping screws, nothing.

Perhaps a bit more detail?  Lacking that...Cobalt-containing bit, low
speed, heavy pressure, cutting fluid.  If the bit rubs instead of
cutting it will round over and require sharpening.

Pilot-point drills are good for easy starting and clean breakthrough,
but if you're drilling multiple layers you'll have to remove a little
disc of metal from the end of the drill after each layer as they cut
deepest at the outside.

If you're not using a pilot-point, you will have to use two or more
sizes.  Examine the point of the drill.  There's a chisel point -- a
line across the end which has to cut by brute-force shoving metal out
of the way.  Your pilot drill for that size should be bigger than the
chisel point, large enough to let the cutting lips get to the edge of
the hole so they can bite.

I use Tap Magic cutting fluid in a Jet-Dry bottle with a blunt 21-ga
hypodermic needle pressed through the hole in the cap, but almost
anything is better than nothing.  Bacon grease or lard are excellent.

The Drill Doctor 500 sharpening machine will save you money if you do
lots of drilling, and save your behind if you run out of sharp drills
in the middle of the night.

Yours,
David