Drilling for conduit

I'd like to run some 2" flexible conduit from the basement to the second floor (possibly attic). I've already got several smaller holes drilled through the first and second floors in this wall. I've also got two access panels on the 'inside' of this center wall. But a recent wiring experience convinced me that I need a better solution.

I've read that a forstener bit with a right angle adapter is the best tool for the job. But considering I need to drill about 12", I'm wondering how difficult it is to control this beast and keep the hole close to straight. I know from my previous adventures that the three stud walls don't line up too well. I was hoping that there is some sort of guide that I could mount between the studs to keep the hole straight.

Any insights appreciated.

Reply to
Bill Stock
Loading thread data ...

Milwaukee makes some drills specifically for this purpose. They are similar to forstner bits except that the outer ring has many teeth along it (but not as many as a hole saw) and there is a screw center to help pull the bit into the wood.

I like the idea of using a right angle adapter. I have been wondering how I am going to get the bit and drill close enough to straight without making a massive hole in the wall.

I would think that once you get the hole started in line with your hole in the wall, that it would be easy to see when a right angle adapter was square to the wall.

Reply to
B Fuhrmann

to forstner bits except that the outer ring has many

help pull the bit into the wood.

When we bought an older home some years ago I needed to do the same thing. The walls were plaster over wood lath and nothing lined up. I found it much easier to locate a closet on the second floor that was partially over another closet on the first floor. I used a Milwaukee hole saw to cut two large diameter holes in the floor of the

2nd story closet and through the ceiling of the 1st. I did the same thing in the first level going down to the basement. I punched through to the attic and installed two wiring cabinets there and two more in the basement. A few offset fittings eliminated the need to bend 2" EMT (I've never been good at conduit bending) to fit snugly onto the corners.
Reply to
Robert L Bass

I've found the secret is to drill inspection holes and have a helper report the bit position as you drill down.

I've used a microcam and white LED taped together to look into holes where I've encountered unexpected obstructions (a broken off hammer head!), but a helper, a teeny flashlight (I use a $12 fiber optic attachment that MagLite sells for its AA flashlight) and some inspection holes along the *intended* path of the bit works well.

You might be able to detect the drill shaft with a studfinder as well, but I've never tried it because I never had a studfinder that would be as good as a small viewing hole. If you're drilling big holes, you're going to do patching work on the walls anyway . . . At least that was my opinion. I was drilling 2 3/8" holes in oak flooring for central vacuuming outlets.

What I would really like is one of the X-ray rigs they use to scan trucks at border for illegal immigrants. No doubt about where the drill's going if you can see it through the wall.

-- Bobby G.

Reply to
Robert Green

I like the inspection cam idea, where did you buy and what model? I put a day/night cam on a model car once to inspect the larger hot air ducts. :-) Yeah, I'm sure there is something else in the way between the top plate and the sole plate, based on my previous drilling adventures.

After taking the wall apart for the third time, I built a permant hatch with J Channel and drywall. It doesn't look TOO bad all painted up. So access is not an issue. There's a similar hatch inside the kitchen cupboards on the main floor.


Reply to
Bill Stock

There's *always* something funky in between the studs. At least there has been in my experience when drilling more than one hole. After angsting about drilling through the overstressed joists in my basement for weeks, I finally decided to strap the vacuum cleaner pipes to the joist bottoms. Not as clean, and it will cost me a few inches come finishing time, but no amount of engineering assurances made me feel comfortable enough to bore

2.5" holes in support lumber in this old house!

The first camera I bought was a small head with the electronics further down the cable. PC233XP Color Microvideocam at Supercircuits.com. It cost $134 but I had other uses for it, so it wasn't just a "search cam."

formatting link
Sadly, it's not listed anymore. Only much more expensive cameras, but that's not a problem. As these things often go, I ended up using the microhead camera elsewhere because the smaller cam's "electronics bulge" got caught on a nail point sticking out of a stud. I thought I was going to lose the whole freaking thing inside the wall but a few minutes of nervous fishing freed it.

It turned out that I had an ExView color bullet cam that lost its water seal and had to be retired from outdoor service but was still quite useful once it had dried out. I realized then that the smooth, streamlined design of the bulletcam was useful to avoid nailpoint and splinter snags. Since I had it opened up to try to restore the seals, I was able to adjust the focus to much closer than its stock setting. Whatever camera you get, close focus ability is an absolute must.

I had a tiny USB Targus LED for lighting laptop screens that I wasn't happy with so I cannibalized it and taped it to the side of the bullet cam. It has a nice, diffuse light perfect for hole scanning! Since the cable comes out the back, bullet cams turn out to be pretty useful for "diving." I've got a little 13" color TV with AV inputs that makes a good viewscreen for searching. I tried using a small LCD handheld, but the resolution's not good enough to make sense of the jumble of junk that's often sitting on the sill plate.

It's easy to see why plumbers have been using access panels for a long, long time.

I'll be there's some hi-tech gyroscopic GPS laser control system for professionals who install a dozen central vacuums a week.

-- Bobby G.

Reply to
Robert Green

For rough in work I prefer Milwaukee Selfeed bits like these:

formatting link

However for what you are trying to do they might not be the best choice. First problem is cost. You only need to drill a couple of holes and $35 is fairly expensive. Second you are likely to hit some nails. In rough in work you can see the likely nail locations and avoid them. A selfeed will mangle it's way past a nail but you will need a stout drill motor to do that. Third is the stout drill requirement, you will not be able to drive a 2 9/16" selfeed with a homeowner type drill and right angle adapter. You will need something like either of these:

formatting link
formatting link

My suggestion would be to use a bi-metal hole saw. Starrett makes the best I have ever used:

formatting link

I also like the A2 arbor:

formatting link

The advantages for your application are:

  1. You can dill a pilot hole first with a 1/4" bit and see where it goes then follow that hole with the hole saw. If you really want to be sure you don't wander replace the arbor's pilot bit with a piece of 1/4" rod.

  1. A bi-metal blade will cut through nails, gently.

  2. Since you are not removing as much material a smaller drill motor can be used.

It will be a slower process with the hole saw than with a selfeed but you don't have that many holes...

If you are drilling through 12" of wood you will need some extensions either way you go. Hopefully you have a 1/2" drill so you can use 7/16" standard extensions. Here is a 12" but they come in various lengths:

formatting link

With a hole saw you will have to stop every inch or so and remove the plug of wood from the hole (or saw). A stout screwdriver is good for that task.

Good luck!

I have no connection to mytoolstore.com and I have never used them. Their site came up quick on Google and their URLs were short...

Reply to
Lewis Gardner

Folks that 'graduate' to a powerful hand drill might not realize that their high torque can make them dangerous if not used with caution and skill. If the bit bind, they don't necessarily stop, rather, they can smash your hands or face or whatever else is in the way.

Years ago, a friend of mine who also something of a tool and safety freak lost a substantial part of his long beard in a split second. Ouch!

Great tip! My knuckles would have appreciated it ;-)

... Marc Marc_F_Hult

formatting link

Reply to

If the baseboards are tall then sometimes you can get away with pulling a section of one and cutting the hole behind it. But then there's usually not enough vertical room to get the drill and bit in there together. So then you've got to cut an opening for an inspection hole and get a cover. Then use extensions are Lewis suggested. There's really no good way to avoid it if you want to drill anything larger that what the usual flexible auger bit can make. You can usually paint the covers if you don't want to repaint the whole wall/room.

I purchased a dewalt cordless right-angle drill a while back (for running some wiring in a boat) and it's been tremendously useful for other stuff too. I've tried the various right-angle adapters over the years and most really aren't worth the hassle. They're generally no good for anything light duty work. But the dewalt has been great for the various holes I've needed to wire up our Russound stuff.

Depending on how much wiring you're doing it's sometimes better to find a good alternative location to run "everything" and cut the wall open. Or even create a box or false panel inside a closet to contain it all. Sometimes you have to factor the costs and hassles of running it where you want, versus running it where it's easier. The added tool and repair work costs sometimes overwhelm what it'd cost in re-routed wiring and replacing a whole section of drywall in that out of the way location.

Just remember if you're using conduit that it's not a good idea to assume you can pull more wire later if the conduit is more than half-full. You end up gouging or otherwise damaging the existing wires if you try to pull more stuff later. And bends in the conduit make that an even bigger hassle. Then make sure you follow the electrical/local codes on dealing with the ends of the conduits.

-Bill Kearney

Reply to
Bill Kearney

I've got a Makita 1/2" Hammer drill. Not as nice as these, but it should do. As Marc indicated I nearly broke my thumb with it once drilling a large hole.

I've got a few Starretts, but none the right size I don't think.

It's not 12 solid inches, just 12" total length required. I like the 1/4" rod idea too.

Thanks for the advice.

Reply to
Bill Stock

Cabling-Design.com Forums website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.