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Lee Schierer
06-29-2010, 8:24 AM
I need to bore a 1-1/2" dia. hole through a 2 or 3 chamber concrete block (not a cinder block) to place an outdoor electrical conduit through an outside wall. I have a conventional drill and a Skill Hammer drill. Can I buy a bit that will cut a nice hole without risk of cracking the block?

I don't want to use a star drill and hammer as I fear the block may crack or the mortar may be damaged in the process plus the hole will l be almost at floor level on one side.

Gene Howe
06-29-2010, 8:39 AM
Lee,
Don't really think you want to do this yourself. The pros use a diamond impregnated corer and one that size will run ya around $200.....and then there is the machine, with the built in water pump, that it takes to use it.:eek:

If you can find a cement contractor in the area, one that does walls as well as slabs, they will have a sub contractor on call who does this type of work.

It will be $$ well spent.

Brad Sperr
06-29-2010, 8:55 AM
If the hole doesn't have to be pretty, or if it's going to be covered up by a panel or junction box, you could try drilling a series of smaller holes and chisel out the waste. I did the same thing with a small hilti hammer drill when I ran conduit through my exterior wall, but that was just through a brick veneer and hollow-core cinder block. This method may not work on solid concrete depending on the age, thickness, and reinforcement.

Lee Schierer
06-29-2010, 9:14 AM
Lee,
Don't really think you want to do this yourself. The pros use a diamond impregnated corer and one that size will run ya around $200.....and then there is the machine, with the built in water pump, that it takes to use it.:eek:

If you can find a cement contractor in the area, one that does walls as well as slabs, they will have a sub contractor on call who does this type of work.

It will be $$ well spent.

What about the Lenox Diamond hole saws? They seem to be well below the $200 cost you cited.

Mitchell Andrus
06-29-2010, 10:33 AM
I need to bore a 1-1/2" dia. hole through a 2 or 3 chamber concrete block (not a cinder block) to place an outdoor electrical conduit through an outside wall. I have a conventional drill and a Skill Hammer drill. Can I buy a bit that will cut a nice hole without risk of cracking the block?

I don't want to use a star drill and hammer as I fear the block may crack or the mortar may be damaged in the process plus the hole will l be almost at floor level on one side.

Rent a drill (if you don't a heavy-duty monster) and core bit at the local rental center. You might want to see if a buddy can help grab a handle. It'll be a big high torque drill with a mean diamond bit. You'll get it done in less time than it will take to drive the tool back.
.

Cliff Rohrabacher
06-29-2010, 10:56 AM
Any cheap " masonry" carbide or carborundum hole saw will do a fine job of boring concrete block. You can get 'em at any hardware store.

Tom Godley
06-29-2010, 3:26 PM
I have a large SDS max hammer drill that I use for this kind of drilling - I would think you should be able to rent one for a lot less than $200.00.

A big hammer drill bit will go through those blocks with little trouble.

I Googled your location -- you are a bit far away to came and borrow it !

Jason Strauss
06-29-2010, 4:05 PM
Lee,

I actually found your questions quite enthralling!:D

David Prince
06-29-2010, 9:43 PM
You can actually get a decent hole using a hammer. The larger the face on the hammer, the larger the hole. Just smack it in the middle where there is a core. I wouldn't worry about it cracking or breaking motar. They are pretty tight. It seems incorrect, but I have seen it done several times and have did it myself and found no problems. And, it is quick, clean, and easy. (I am talking holes up to around 2 - 2 1/2 inches in diameter. Larger than that may be best suited with a core bit)

neal jack
06-30-2010, 2:57 AM
You can actually get a decent hole using a hammer. The larger the face on the hammer, the larger the hole. Just smack it in the middle where there is a core. I wouldn't worry about it cracking or breaking motar. They are pretty tight. It seems incorrect, but I have seen it done several times and have did it myself and found no problems. And, it is quick, clean, and easy. (I am talking holes up to around 2 - 2 1/2 inches in diameter. Larger than that may be best suited with a core bit)
seems great suggetion