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Thread: Boring question

  1. #1
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    Boring question

    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.
    Last edited by Lee Schierer; 06-29-2010 at 9:08 AM.
    Lee Schierer
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  2. #2
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    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.

    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.
    Gene
    Life is too short for cheap tools
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  3. #3
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    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.

  4. #4
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    Quote Originally Posted by Gene Howe View Post
    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.

    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.
    Lee Schierer
    USNA '71
    Go Navy!

    My advice, comments and suggestions are free, but it costs money to run the site. If you found something of value here please give a little something back by becoming a contributor! Please Contribute

  5. #5
    Quote Originally Posted by Lee Schierer View Post
    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.
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  6. #6
    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.

  7. #7
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    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 !

  8. #8
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    Lee,

    I actually found your questions quite enthralling!

  9. #9
    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)

  10. #10
    Quote Originally Posted by David Prince View Post
    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

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