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Thread: Core Drill

  1. #1
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    Core Drill

    Not sure if this is the right section of the forum, but I'm not seeing anything specifically about tools.

    I'm looking into getting a hand held core drill. A local plumber occasionally lends me his Eibenstock when I need it and I leave him a 20 in the box when I return it to his shop, but I need my own. It works great, but I find that it is a bit tough to get holes lined up neatly with the hand held drill since it walks around some when you initially start drilling the hole. I'm wondering if anyone knows of a hand held drill that has a simple wall mount guide attachment.

  2. #2
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    Quote Originally Posted by Speshulk View Post
    .... It works great, but I find that it is a bit tough to get holes lined up neatly with the hand held drill since it walks around some when you initially start drilling the hole. I'm wondering if anyone knows of a hand held drill that has a simple wall mount guide attachment.
    Core drill (or hole saw) some "buttons". For example, hole saw a few holes in some FRP (or other resilient flat stock) and save the "cores", aka "buttons". Now when you go to core drill a hole, layout the center of your hole(s) and screw one or more "buttons" to the center. This will keep your core bit from walking. Save "buttons" for future use. I left size out of the steps but I think you'll figure out on your own how size is relevant...
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  3. #3
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    If you're using hollow circular dry core bits they come with a pilot bit for starting the hole.

    Rob

    Moderator

    All responses based on the 2014 NEC unless otherwise noted

  4. #4
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    Dry core or wet core?

  5. #5
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    Quote Originally Posted by infinity View Post
    If you're using hollow circular dry core bits they come with a pilot bit for starting the hole.

    If you had to, you could probably use a hammer drill to start the pilot hole.

  6. #6
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    Quote Originally Posted by Cow View Post
    Dry core or wet core?
    the one's rob pictured are dry core. i've got a couple,
    stick them in the hammer drill, and away you go.
    mine are hilti's.

    price them sitting down, with a stiff drink.

    rebar is the kiss of death for them. i needed a couple holes,
    but if you really need holes, a wet drill is really what needs
    to happen. they are slow, in my experience.

    hilti makes a high speed dry drill, but it's gawdaful expensive.
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  7. #7
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    Quote Originally Posted by Fulthrotl View Post
    the one's rob pictured are dry core. i've got a couple,
    stick them in the hammer drill, and away you go.
    mine are hilti's.

    price them sitting down, with a stiff drink.

    rebar is the kiss of death for them. i needed a couple holes,
    but if you really need holes, a wet drill is really what needs
    to happen. they are slow, in my experience.

    hilti makes a high speed dry drill, but it's gawdaful expensive.
    At my last job we always subbed out the coring. I think anything over 4-6" was wet.

  8. #8
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    Quote Originally Posted by gadfly56 View Post
    At my last job we always subbed out the coring. I think anything over 4-6" was wet.
    in my experience, anything beyond a single hole or two, i call a guy....
    if i wanted to be a core driller for a living, i'd not have bought a wiggie...

    one thing i did buy when i had a bunch of layout for coring was this
    thing from hilti... it is expensive, but very worth it.

    it will lay out thru penetrations up to about 4' thick. you put the transmitter
    on one wall, making sure it's square to the path of the conduit, and go
    to the other side... you'll see where it comes out within a quarter inch or so,
    and how many inches thick it is.

    https://www.us.hilti.com/measuring-s...-systems/r3538
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  9. #9
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    Quote Originally Posted by Smart $ View Post
    Core drill (or hole saw) some "buttons". For example, hole saw a few holes in some FRP (or other resilient flat stock) and save the "cores", aka "buttons". Now when you go to core drill a hole, layout the center of your hole(s) and screw one or more "buttons" to the center. This will keep your core bit from walking. Save "buttons" for future use. I left size out of the steps but I think you'll figure out on your own how size is relevant...

    Great idea, but I think I'll try the reverse. I have about a dozen holes to drill on 2 different buildings. Instead of keeping the cores, I'm thinking I'll just pre drill my pattern into a piece of plywood and attach it to the wall to use as a guide. Thanks!

  10. #10
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    Quote Originally Posted by Speshulk View Post
    Great idea, but I think I'll try the reverse. I have about a dozen holes to drill on 2 different buildings. Instead of keeping the cores, I'm thinking I'll just pre drill my pattern into a piece of plywood and attach it to the wall to use as a guide. Thanks!
    I've used this method too and it works well also.

    The reason I brought up the buttons method first is because you can attach the guide to what is going to be removed and leave no trace. Attaching "button holes" usually leaves a trace.
    I will have achieved my life's goal if I die with a smile on my face.

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