low power drilling

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?

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

Reply to
clare

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?

Allen

Reply to
allen476

On Thu, 11 Mar 2010 22:48:43 -0500, the infamous snipped-for-privacy@snyder.on.ca scrawled the following:

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

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?!?

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

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? 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.

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

-- There is no such thing as limits to growth, because there are no limits to the human capacity for intelligence, imagination, and wonder. --Ronald Reagan

Reply to
Larry Jaques

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.

Reply to
CW

----------------------------------------- This is a TOTAL PITA solution, but it will get the job done.

Drill a 1/4" dia pilot thru every 2x8, then it is time for a 1-1/2" hole saw AND a 1/2" right angle drill.

If you question the need for a right angle drill, you have never used many hole saws.

Nuf said.

Drill each 2x8 about 1/2-3/4 way thru then try to break out plug and remove from hole saw.

Now back drill from the other side to complete hole.

Labor intensive, slow, and a probably got to stand on your head kind of job, but it will do the job.

IOW, a total PITA.

Have fun.

Lew

Reply to
Lew Hodgett

Hole saw and angle drill. One joist at a time.

Reply to
LDosser

If I understand correctly what he wrote, he doesn't have any access--he has to drill the first joist and then drill the second one through the hole in the first, and so on. The difficulty seems to be the 12 feet of extension--not extension _cord_ but bit extension.

Reply to
J. Clarke

On 3/11/2010 10:06 PM Lew Hodgett spake thus:

I wonder if you really read the OP's post. Otherwise, the only way he'd be able to use your suggestion would be if he could scrunch his body down to fit in a 7-1/2" high space between a concrete slab and the decking. Quite a trick, that.

What I don't understand is when he says the joists are "only accessible from the one side". What does this mean? That the openings between joists are only accessible from one side of the house? I'm having a hard time picturing this. And how the hell would he get in there in the first place--drill a hole from the outside through the rim joist, then each joist in turn after that?

Reply to
David Nebenzahl

On 3/11/2010 10:08 PM LDosser spake thus:

So I'll ask you the same question I asked the other fellow who suggested a hole saw: how the hell is this guy supposed to get into that 7-1/2" high space to use it? You must think he's some kind of Houdini.

Reply to
David Nebenzahl

---------------------------------- "David Nebenzahl" wrote:

-----------------------------------

Depends how you interept thev above phrase:

" I need to drill through 6 2X8 joists which are accessible only from the one side."

I interept that to mean he has access to one side such as floor joists in a house with a basement.

Lew

Reply to
Lew Hodgett

On re-reading, it appears you are correct and I am wrong. I'd pull the plywood!

Reply to
LDosser

Buy a Boa? :)

Reply to
LDosser

He also said: "The joists are sitting directly on concrete, and the decking is 1 1/2" (you read that right) plywood."

Reply to
LDosser

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

Reply to
allen476

On Fri, 12 Mar 2010 00:30:52 -0800, the infamous "LDosser" scrawled the following:

Yeah, a boa contractor.

-- There is no such thing as limits to growth, because there are no limits to the human capacity for intelligence, imagination, and wonder. --Ronald Reagan

Reply to
Larry Jaques

On Fri, 12 Mar 2010 06:47:26 -0800, Larry Jaques saw and angle drill. One joist at a time.

How about a flex shaft driving the bit?

Reply to
Upscale

No a feather boa, and take up dancing.

Reply to
Bob La Londe

A spade bit might have a rough punch-through, so go slow and have patience at the end point. Make sure the bit is sharp. I think I would try welding a spade bit onto a 1/2" pipe and make a separate chuck insert (fitted/welded onto a 1/2" sleeve, for the pipe) for fitting into the drill chuck. A spade bit is a lot cheaper than an auger bit for a one-time use (once welded).

If access space, in starting, is limited, also, the 1/2" pipe can be in successive 24" - 36" sections. Any connecting sleeves will pass through the 1-1/2" holes and the chuck insert fitting can be moved back, as each successive pipe section is attached. Save the set-up for future use (???, LOL) and use the pipe sections for pipe clamps.

Sonny

Reply to
Sonny

I've drilled some long applications. About 8' is the longest, and never with the size cutter you are talking about. Depending on what you are using for extensions gravity can be a factor also. Break out may not be all that important depending on the application, but all bits I have used experience break out in wood. Some worse than others.

I have lost bits and extensions inside walls and other spaces. That is something to be avoided if you can, but there are a few of my bits still in some of those places.

Given that you are making multiple holes through 2 by you will want to consider that the bit will dull slightly after each penetration. To minimize breakout you will want to have a couple bits or atleast the ability to sharpen the cutting edges.

You may want to consider some kid of sleeve and a helper to hold the sleeve level (or slightly above level) while you work. If you are on the clock it may be cheaper and faster to just remove decking as some have suggested. Even if you have to replace some of it.

Reply to
Bob La Londe

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