On Sun, 14 Mar 2010 05:44:03 GMT, Al
wrote:

On Thu, 11 Mar 2010 22:46:55 -0500, clare 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?

used to work in the pile driving business, had to bolt piles together for
breakwaters, welded the 1" bits onto 4-5' rods. 1 person would hold the
centre of the rod to keep the wobble down. will take some work to keep
the holes lined up straight because of the spaces between the joists will
allow the bits to drop.
dropped about 3 inches in 12 feet.