On Mon, 21 Aug 2006 10:49:44 -0400, "HotRod"
wrote:

I'm working on a retianing wall project that involves using busted up old
concrete slabs. I need to drill a ton of 3/4" - 1" holes as the blocks get
higher, any ideas? Also ideas on how to crack the 4" thick concrete where I
need to? Do you think a peice of angle iron and a sledge is best?

If you have that many to drill, you want a rotary hammer and
appropriate bit, not a hammer drill. They both work by apply
repetitive impacts inline with the bit while it is turning, but the
rotary hammer applies a much more forceful impact. The rotary hammers
require a special shaft on the bit, of which there are two or three
common styles. You can do this with a hamme drill, but the rotary
hammer will drill 3-4 or more holes in same time the hammer drill will
drill 1.

Go to www.toolsofthetrade.net and select the tool test archive. They
have reviews of both hammer drills and rotary hammers.

If there is rebar in the concrete, you will need a bit designed to
handle it, because you are sure to hit some. (And if there is rebar,
your efforts to cut it or break it are going to be very
frustrating...)

HTH,

Paul