or Connect
AVS › AVS Forum › Home Entertainment & Theater Builder › General Home Theater & Media/Game Rooms › Drill bit sizes for flexible conduit?
New Posts  All Forums:Forum Nav:

Drill bit sizes for flexible conduit?

post #1 of 23
Thread Starter 
What're the typical size and type of drill bits for putting holes through framing to run flexible ENT conduit (aka smurf tube)?

I'll be running mostly 1" flex and a few 2". It's new construction and I'm, worst-case, going through no more than 6" of wood.

What's the right sizes? And which style will work best?

I'm assuming I'll need to purchase 2 each. I intend to avoid hitting any nails but I'd rather have a spare bit handy just in case (rather than wait for shipping).

Thanks!
post #2 of 23
I use a 2.5" hole saw for my 2" Carlon orange conduit. The Carlon orange 2" conduit has an outside diameter of 2 and 5/16".

The Carlon orange 1.5" conduit has an OD of 1 and 29/32". I haven't had to drill a hole for it.

I bent my first hole saw mandrel (combo mandrel and hole saw); Home Depot refunded, and I got a more expensive combo mandrel and hole saw from HD. The upgraded one has held up OK, but no longer has a manufacturer's label. I believe it is Ridgid brand, from the orange color.

Many hole saws come without the center mandrel, you may need to order separately.

Hole saw cuts take a lot of effort. A corded drill might be useful to have on hand, if you have many cuts.

Edit - found the Carlon conduit brochure which states the ODs, page 89. Use the 'Max OD' column. For 1", looks like 1.312"

http://www.carlonsales.com/techinfo/brochures/lvpremise/Flexible_Raceway_Brochure.pdf
post #3 of 23
Thread Starter 
Thanks, that clarifies things. The carlon website has a lot of literature, finding that one helps. I've got two different hole saw mandrels now, one Rigid and the other Milkwaukee, along with several hole saws.

I'm wondering whether picking up some large forstner bits might be worthwhile. Time saved on drilling the holes adds up. Clearing the chunks out of typical hole saws is a hassle, and not typically convenient to do while on top of a step ladder. Thus my thought of using a forstner or similar kind of bit comes to mind. Since it's new construction I'm not concerned about the added mess of wood shavings.

I've got 10' ceilings and 14" wide joist bays to contend with. I've got a Dewalt right-angle cordless and it's great for this sort of access. I've thankfully got several batteries and chargers and do expect to go through them. In the few places where I have better access and need more torque I'll use a corded drill. I've got a medium-sized one that should handle it.
post #4 of 23
I use Irwin Speedbor bits and an impact driver. Here's a 1-1/2" one: http://www.amazon.com/Pack-Irwin-3041021-Speedbor-Spade/dp/B002V5P8HM/ref=sr_1_63?s=hi&ie=UTF8&qid=1363787904&sr=1-63&keywords=irwin+speedbor+wood+bits The chips really fly with this combo.
post #5 of 23
I use those Irwin Speedbor bits for smaller holes - very good tools. I guess you could use one of those for your smaller 1" conduit holes. But I think you're stuck using a hole saw for the larger cutouts.

Hopefully, a good number of your holes will be drilled off of the ladder; drill down when possible. Use nail plates when needed. Keep the conduit runs as straight as possible.
post #6 of 23
The one I linked is a 1.5" - the right size for his conduit. As I said, chuck it up in an Impact Driver and watch the wood fly! biggrin.gif
post #7 of 23
Thread Starter 
Right, I've got both 1" and 2" flex conduit going in, along with a number of wires without conduit. I'm only putting the conduit in places where it'd really be advantageous to change later (like the outside walls that are getting spray foamed. But for some stuff it'll be just fine to run regular in-wall wire without the conduit.

Hard to decide whether to get the self-feed or auger kind (and then whether to spring for ones rated to handle nails).

Looks like I'll pick up a set of the regular auger kind, so I've got a few in-between sizes for the wire-only holes. Then probably a long 1/2" auger for a specific set of places that'll need it. I'll have to double-check the total thicknesses of areas that would have the 1" and 2" conduits going through. A few might have more than one 2x4 (king stud situations) so I'd certainly need either longer bit or an extension.
post #8 of 23
I learned when installing deadbolts in all the doors of our new house that the cheap hole saws are NOT worth it. I went with the Milwaukees and was quite happy smile.gif

I've never used a spade bit over 1.5", but I'd argue a good hole saw would be faster and easier
post #9 of 23
Thread Starter 
Sure, a hole saw is very likely to be faster than a spade bit, no question. At least not for framing material. Through something thin it wouldn't matter much either way. But I'm definitely dealing with all framing lumber, with some having 3/4" advantech subfloor (OSB, essentially).

The question is whether I should go with augers or the self-feeding kind. The latter being sort of a combination of a spade and a hole saw.

And yes, cheap hole saws are to be avoided.
post #10 of 23
Quote:
Originally Posted by NickTheGreat View Post

I learned when installing deadbolts in all the doors of our new house that the cheap hole saws are NOT worth it. I went with the Milwaukees and was quite happy smile.gif

I've never used a spade bit over 1.5", but I'd argue a good hole saw would be faster and easier
I've never used a spade bit over 1" either. That's why I like the SpeedBor / Impact Driver combo. The one I linked is a three flute auger bit. I'll have to shoot and post a demo video. wink.gif
post #11 of 23
Thread Starter 
I've ordered a couple of different bits. Both auger and self-feeding kinds. I'll report back what sort of performance I get out of them.
post #12 of 23
a sharp self feeding ship auger bit will make quick work of your 2x dimensional lumber, just be sure to avoid any nails........quickest way to compromise your expensive bit.
Be very careful is using the larger drills these bits require, make sure you are not in the way of the drill body swinging into you if the bit jams. I've seen two broken arms from drills spinning into their users and have knocked myself off a step ladder. Was very grateful that my latest employer invested in in a Bosch with a clutch.
Edited by weaselfest - 3/23/13 at 4:53am
post #13 of 23
Thread Starter 
Yep, ordered a set of Irwin's 'weldtec' augers, along with two self-feeders and a hole saws. I also checked and local stores have similar bits in stock. I've learned over the years it's better to be over-equipped and get the job done, than under-equipped and have to waste time when things break.

It's new construction so I can see all sides of the wood and can probably avoid most nails.

There's one piece where the framers went a bit overboard with the nail gun, but I plan on removing that section and replacing it. It's the top plate of narrow bit of wall that was studded out in front of the exterior wall, specifically to provide a chase for 2" conduits. They just nailed the bejesus out of the top of it, for no apparent reason. Easier to cut the whole piece out with a sawzall (whose blades are MUCH cheaper) and replace it with one nailed more effectively. Better that than wrecking a bit and slowing the job.

One remaining question will be how well my existing corded drill will handle the bits and the wood. I ran a few tests with my 18v cordless dewalts and they're not quite up to the task. Yeah, they'll work but it'll take a lot longer than it would with a corded drill. I may end up renting a higher-end right-angle one just to be sure. But I'll get everything else drilled out first in order to maximize the rental time. I just don't see much need to own a $300+ right-angle beast of my own. I've got a cordless right-angle one that's good enough for 99.9% of the work I'm ever likely to perform. It's bad enough I had to shell out for a new 8' tall stepladder. The new house has 10' ceilings and my old 6' stepladder just wasn't high enough to do the job right.

Now I'm off to pick up some more 2" conduit...
post #14 of 23
For posterity here are the vids of the speedbor and an impact driver:
post #15 of 23
Quote:
Originally Posted by wkearney99 View Post


One remaining question will be how well my existing corded drill will handle the bits and the wood. I ran a few tests with my 18v cordless dewalts and they're not quite up to the task. Yeah, they'll work but it'll take a lot longer than it would with a corded drill. I may end up renting a higher-end right-angle one just to be sure. But I'll get everything else drilled out first in order to maximize the rental time. I just don't see much need to own a $300+ right-angle beast of my own. I've got a cordless right-angle one that's good enough for 99.9% of the work I'm ever likely to perform.

Now I'm off to pick up some more 2" conduit...

I have one of those $300 angle drills, and it's amazing, plus it doesn't kick back much if you stop it (unlike my cordless drill, which almost 6takes ma hand off).
post #16 of 23
might be money well spent to stop by the rental shop and pick up a big right angle drill for the afternoon
post #17 of 23
Thread Starter 
Did a bunch of the holes this afternoon. Let me tell you, the money spent for the weldtec nail eating upgrade was WELL WORTH IT. First hole I have to drill hits a nail. Damn near too my arm off when it kicked back. But the bit survived and went on to cut at least another two dozen holes. This was the 3/4" ship auger size. I also picked up a 2-9/16" self-feeder and it likewise did a phenomenal job. Chewed through three 2x4s like butter. But it did tend to bind up quite suddenly if I wasn't careful about keeping it nearly dead-straight. It took nice big clean CHUNKS of wood out in the process. Had to use the open hose from the shop vac to clean up the mess from it. Whereas the ship augers cut much smaller pieces.

One observation though, a 2-9/16 isn't quite wide enough for the bell-end of 2" gray PVC conduit. Which is ok for my particular situation as I don't need to feed pieces that way.

My cordless 18v DeWalt handled the 3/4" ship augers just fine. But for a 1-3/8" auger and the 2-9/16" it just didn't have enough torque. Fortunately I brought along a corded 3.8a hammer drill and it worked great. But I did have three situations that I couldn't quite get in there tight enough. I will need to pickup a right-angle unit. Sunbelt rents then locally for $20/day. And I really don't have much long-term use for a corded right-angle drill.

That and there's definitely something to be said for extensions. There are a couple of places where the typical 17" bit is just too long. But a regular 6" one is too short. I'm going to pick up a shorter extension. I've got one corner where I could use the 6" bit if I had another 6" extension. They do sell 12" bits, and that would work too.
post #18 of 23
Quote:
Originally Posted by wkearney99 View Post

I also picked up a 2-9/16" self-feeder and it likewise did a phenomenal job. Chewed through three 2x4s like butter
You might want to read the parts about allowable hole sizes in this. Sounds like you compromised the structure.
post #19 of 23
Thread Starter 
And you know this, how? By assuming? Don't.

I'm well acquainted with what is or isn't structural in a building. The area in question was a built out section specifically added to house the conduits. Not part of structure at all. More a matter of how the carpenters chose to frame it both above and below the subfloor. I've got the actual plans that lay out what is or isn't structural or load bearing, as approved by licensed engineers and the county.

I've already seen the Simpson literature as we've got their products used in quite a few locations in the house. Quite a nice variety of products. Their nail stops get added as we move along.
post #20 of 23
Quote:
Originally Posted by wkearney99 View Post

And you know this, how?
You said you put a 2 9/16" hole through a 2x4. That pretty much compromises the structure at that point, whether it is load bearing or not.
Quote:
By assuming?
Obviously not.
Quote:
Don't.
You might want to worry more about what you do than what I do.

I find it somewhat ironic that you know so much about construction and are asking what kind of drill bit to use.

If you don't find what I have to say useful, just ignore it. I am sure you will, anyway. But I will mention it for anyone else who might happen to read this thread and think it is a good idea to put that size hole in a 2x4.

Anyway, have fun making holes. I won't bother you again in this thread.
Edited by Colm - 3/23/13 at 6:40pm
post #21 of 23
Quote:
Originally Posted by Colm View Post

You said you put a 2 9/16" hole through a 2x4. That pretty much compromises the structure at that point, whether it is load bearing or not.
Obviously not.
You might want to worry more about what you do than what I do.

I find it somewhat ironic that you know so much about construction and are asking what kind of drill bit to use.

If you don't find what I have to say useful, just ignore it. I am sure you will, anyway. But I will mention it for anyone else who might happen to read this thread and think it is a good idea to put that size hole in a 2x4.

Anyway, have fun making holes. I won't bother you again in this thread.

I agree, that's unlikely to pass inspection. see page 4 here, for instance:

Buiding codes
post #22 of 23
For the record, I didn't pass my 2" conduit through any framing members, only through floors/ceilings of the chase.

Bill, let it go. They are criticizing without seeing what you did. Get some thicker skin.

From what you describe, it sounds to me like this chase is constructed like a soffit, and totally separate from the framing members.
post #23 of 23
Thread Starter 
Quote:
Originally Posted by Neurorad View Post

From what you describe, it sounds to me like this chase is constructed like a soffit, and totally separate from the framing members.
You make an excellent observation, thank you.
New Posts  All Forums:Forum Nav:
  Return Home
AVS › AVS Forum › Home Entertainment & Theater Builder › General Home Theater & Media/Game Rooms › Drill bit sizes for flexible conduit?