On Mar 12, 12:56*am, "CW" wrote:
"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.

But 10' of extensions will be the real PITA. If you don't get the set
screws tight, you'll be ripping up the floor.

Did 6' like that once. Never again.

Allen