If it really really concrete, use Powers brand Wedge Bolts:

http://www.powers.com/product_07246.html

These require a special high tolerance drill bit for the lead hole
and suggest an impact gun for installation. Excellent anchor.

Pull out values he
http://www.powers.com/pdfs/approvals...-Bolt-2001.pdf

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Keep the whole world singing . . . .
DanG (remove the sevens)




"Doug White" wrote in message
...
I am going to hang a METAL extension ladder using some METAL
hooks. Now
that I have established some serious metal content, I need to
drill the
mounting holes in the concrete garage wall. The hooks have 3
holes, and
I'm going to use plastic expansion anchors for the screws.

I have a nice Bosch hammer drill, but my past experience has
demonstrated
very poor success at getting holes where I want them. The drill
wanders
& bounces off pieces of agragate in the concrete, and I end up
with holes
that won't match up with the holes in the
bracket/fixture/whatever. I've
tried using a star drill as a centerpunch, but that only helps a
little.

It seems to me that the absolute error gets worse with bigger
drills, so
I can try starting small and then boring out the hole with a
bigger bit.
Another option is to drill the first hole, and then use the
hooks as a
jig to ensure that the subsequent holes line up. I was thinking
about
using a small bit with a sleeve that fits in the holes in the
metal hooks
to prevent the drill bit from chewing things up.

Any suggestions or tips from the experts out there?

Thanks!

Doug White