"allen476" wrote in message
...
On Mar 11, 10:48 pm, wrote:
On Thu, 11 Mar 2010 22:46:55 -0500, wrote:
I've got myself into a situation -
I need to drill through 6 2X8 joists which are accessible only from
the one side. They are spaced 2 feet on centers. (need to pull cable
across to the center of the floor). The joists are sitting directly on
concrete, and the decking is 1 1/2" (you read that right) plywood.

What is the lowest power-requiring type of drill to use/ since it
needs to be run on a 12 foot long extension-----.
I tried a speed-bore type spade bit, but it has a bad habit of
"catching" just as it breaks through - putting a severe strain on the
connection between the bit and the extension.

Would a forstner type work better? Or an auger?

Still looking for a viable bit extender setup as well - thinking I
might need to go to 1/2" steel waterpipe with a 7/16 or 1/2" hex shaft
welded into the one end for the chuck to grab. In 3 or 4 foot length
with couplers it should be handleable?

Forgot - the hole needs to be 1 1/2 inch diameter

You would want to use an auger bit, but at that length you will be
looking at a custom bit. Not cheap but if you DAGS "custom made auger
bit", you will find some that make them. Why does your hole have to be
that big?

A regular auger bit on extensions should do it. It only goes threw one board
at a time.