On Thu, 11 Mar 2010 21:15:07 -0800, Larry Jaques
wrote:

On Thu, 11 Mar 2010 22:48:43 -0500, the infamous
scrawled the following:

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 does the decking have to do with drilling joists? You don't want
to pull it?

It is gled and screwed to the joists so it can not be removed without
destroying both.


What is the lowest power-requiring type of drill to use/ since it
needs to be run on a 12 foot long extension-----.

Use a 12ga extension. HF has 25' x 12ga for $10 which are nice. I use
mine all the time for their 12" SCMS. YOu don't mean 12' metal
extension, do you?!?

Yes TWE:LVE FEET.

I did it this afternoon. bought a 12 inch 7/15 AF extension and cut
it in half. Banged the cut end of each peice into a 1.4 to 3/8 NPT
bushing and mig welded it in. Put that bushing into a 1/2 to 3/8NPT
reducer and threaded it onto each end of a 4 ft piece of 1/2"
galvanized water pipe. Chucked a 1 1/2" forstner bit into the hex bit
holder end, and chucked the other end into a 450RPM half inch drill.
When I got in 4 feet, I took off the drive end with s pipe wrench and
using a pipe couipling, added another 4 feet, and so on untill I was
in all the way.


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?
Augers self-feed and don't break out as hard. There are short auger
sets available if you like 'em.


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?

Oh, you do mean physical, not electrical. Why don't you just unscrew
the decking and have a friend help lift it? Or did some jerk just
nail it in? grrr Ooh, flooring might be glued, too, huh? Skilsaw,
cut a long slot, lift it, replace and reglue with caulk as an
adhesive. Cost: 1 sheet of flooring. Time saved: a day. Frustration
saved: Humongous amounts.


Did you read ONE AND A HALF INCH THICK PLYWOOD????

Doing it with the water pipe took almost half an hour for the first
hole, and 10 minutes for the second one. Making the tool took 1/2 hour
at the "borg" getting parts, and half an hour at the fabricating shop
cutting and welding.

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

I'd hold my light sabre down there for a couple quick punches through,
one from each side. No extension necessary.