Doug White wrote:

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.

I made a center punch by welding a blob of #6 Stellite ont the end of a
piece of rebar and machining (carbite cutter) an appropriately shaped
point. I've center punched quite a number of starters in concrete with
this. For just three holes, a piece of drill rod hardened and tempered
should do.

Those plastic thingies are junk. Epoxy a piece of threaded rod into
slightly oversize holes (e.g. 9/16" hole for 1/2" threaded rod). This
is far stronger (and cheaper) than expansion fittings.

Ted