low power drilling

[EXT]

I don't see any drill working, as the shaft diameter is always much smaller than the drill bit. To drill 6 joists with a 1 1/2" bit means the bit will drop about 5/8" with each hole as the shaft rests on the previous hole bottom, 5/8" x 5 joists (I am assuming the first hole will be accurate) = 3

1/8", so you will either have to start real high on the first hole or hit the concrete with the last hole. I cannot think of any way of getting such a large hole drilled through so many joists in one go. Can you not go around the ends and come in from there some how?

[Mike M]

We had to drill out a boat hull for a prop shaft and ending up welding an auger bit to a metal shaft. Had a jib for rolling the shaft and bit to get a good weld and hold everything true. A heavy wall pipe might work ok but we used solid. Did some grinding to be able to get a lot of fill.

Mike M

[David Nebenzahl]

On 3/12/2010 12:17 AM Lew Hodgett spake thus:

Guess you missed that part, eh?

[J. Clarke]

Just needs a steady rest.

[whit3rd]

Well, a drill that makes minimum sawdust uses lowest power; I'd consider a length of black iron pipe with a tack-welded hole saw on the end. If you support the iron pipe outboard of your deck to be level, it should shoot straight enough to get to the destination.

Just get a (disposable) hole saw and a 20' length of pipe, fit 'em together and put a T handle or brace-and-bit on the drive end. One or two supports to keep the shaft level (you can drill the first hole with a standard setup, the shaft will rest in that hole and you will want to level it carefully before doing the second).

After each punch-through, retract the drill and pull out the wood plug.

It'll take a half day.

[Lew Hodgett]

------------------------------------ Not engaging brain late at night will do that to ya.

Mea Culpa.

Lew

[Lew Hodgett]

RE: Subject

After rereading and hopefully understanding the problem, short of opening a seam thru that 1-1/2" plywood, as others have suggested, you can't get there from here.

Unless.....................

You approach this problem like drilling a well, only horizontally which will require significant cost to built all the componet parts.

Opening up a seam will probably less costly.

Back to basics, why is drilling necessary?

What is the purpose?

Lew

[Dave Balderstone]

I'm with you on this one, C-less.

He gets through 4 of the 6 joists, and whatever rig he's using snaps somewhere between #3 and #4, with the bit embedded in #5 becuase he's hit a knot... Start again.

How many times, and at what cost?

Clare... Don't be stupid. take the easy way.

[Dave Balderstone]

As he said, he needs a cable pull.

I'd open a seam, notch the top of the joists, lay the cable (in a conduit would be smart for future access so you could use a snake) and seal the decking again.

[clare]

Have to pull 4 #12 BX cables through it

[Nonny]

Above the edge of each joist, drill (4) 1/2" holes centered over the joist and approximately 4" OC parallel to the joist and 2" OC across (spanning) it. Insert a saber saw with 1-3/4" long blade through the hole and cut across the joist and alongside it, connecting the holes. Pry the 1-1/2" plywood out of the hole and set aside. This will expose approximately 4" of the joist. Using a longer blade in the saber saw, cut a 1-1/2" to 1-3/4" wide slot in the joist, breaking the piece out. This will leave you with a rectangular cut in the joist adequate for your 1-1/2" pipe or conduit.

Glue and screw the removed plywood flooring back over the joist after you've run the pipe, leveling it with floor patching compound.

[clare]

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

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.

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.

[clare]

Except haw are you going to get down between the joists and between the concrete floor and the raiised decking?.

You did not understand the problem. NO ACCESS. Only the face of the "platform" is accessible.

[clare]

Got a midget to go with the drill? Deck is 16 inches from the floor, joists are 16 inches high. No access from the sides.

[clare]

Give the man a medal - HE can read!!!!!

[clare]

OK - not in a house. Raised floor in what WAS an auditorium (theatre). Being made into office space.. The "face" of the platform (raised seating area) is all that is accessible. Need to get power and data into the center of that raised floorspace for 6 work-stations.

Make more sense now??

[clare]

how about where I stated "They are spaced 2 feet on centers. (need to pull cable The joists are sitting directly on concrete, and the decking is 1

1/2" (you read that right) plywood..

I have access to only one side of ONE joist.

[clare]

You'd pull 1 1/2 inches of glued and screwed plywood? Destroying both the plywood and the joists?????..

It took me just over an hour to manufacture the tool and do the job. With no damage to the structure.

[clare]

I know, I bought a couple of 18" extensions to drill down the wall in my daughter's townhouse to install wiring for bedroom ceiling lights. Paid $18 each for the extensinsa, and stripped one on the first hole. Thanfully the second didn't need as much length.

This time I used 1/2" water pipe, threaded together with pipe couplings.

[clare]

The half inch water pipe was almost too flexible.