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Thread: How do I increase a 3/8" hole to 1/2"

  1. #1

    How do I increase a 3/8" hole to 1/2"

    Only way I can think of is to get a metal plate drilled with a ½" hole and center it over the 3/8" hole.
    How to center the plate I haven't figured out yet.
    Suggestions?
    TIA

  2. #2
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    Plug the hole with a dowel and drill it to 1/2".
    Chris

    Everything I like is either illegal, immoral or fattening

  3. #3
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    Do You have a forstner-type bits?

    If so, drill a 1/2" hole in a piece of scrap, plywood or whatever. Center that hole over the 3/8" hole, secure the scrap piece with double stick tape or brads or screws, the 1/2" hole will keep the forstner bit centered and drill the 3/8" hole out. I hope that makes sense.

    Curt

  4. #4
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    Think of the 3/8" hole as a pilot hole and drill it out with a 1/2" bit.
    Tom Veatch
    Wichita, KS
    USA

  5. #5
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    Why can't you just stick your drill or drill press chucked up with a 1/2inch bit against the 3/8 inch and drill a larger hole?
    Vortex! What Vortex?

  6. #6
    Sorry, didn't explain that it's a large piece that can't fit onto a drill press.
    And when I use the 3/8" hole as a pilot hole the handdrill just runs amok.

  7. #7
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    You could try something like this to locate the 1/2" hole if centering needs to be really exact. Take a piece of scrap wood and drill a 1/2" hole halfway through it with a forstner. Switch to a 3/8" and drill the rest of the way through. Doing this on a DP with the scrap clamped down would work best but the spur point from the first hole would locate the second one if you have to do it with a handheld. Then stik a 3/8 dowel into your existing project hole and slip the scrap plate onto the dowel with the 1/2" side up. Clamp the plate to it, pull the dowel, and use the 1/2" counterbore to drill the rest of the way through the plate and into the project.
    Use the fence Luke

  8. #8
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    You didn't mention two things in your original message. 1-hand drill, no drill press, and 2- using forstner bit.

    Based on that I would drill the 3/8" hole out with a 1/2" twist bit but not to full depth. Then chuck the 1/2" forstner bit and finish the hole. This will allow you to use the outside diameter as the guide for the forstner bit instead of the center spar.

  9. #9

    wrong hole

    If you can use a hole saw there is an oops arbor. The arboe will take two different size saws one the hole size and a second one with the correct bigger size. I don't know if the Borgs sell them but they're available mailorder.

  10. #10
    I recommend plugging it and redrilling it. Don't ruin the piece by making a small mistake a huge one.

  11. #11
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    Step bit?

    44460.gif
    Happiness is like wetting your pants...everyone can see it, but only you can feel the warmth....

  12. #12
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    As Chris and Kevin has mentioned, plug it with 3/8 dowel.. find true center and re-drill. I have been most of the other routes and you won't be dead on without having the drill tip define center.

    If it is utility hole that is not necessary to spot "right on".. then just drill a 1/2" hole in a piece of scrap.. center it best as possible and clamp it. Then drill as the scrap hole will serve as a template to hold the bit verical...

    Sarge.

  13. #13
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    myself the best tool is a reamer. 1/2" is a bit of a jump but a chucking reamer will follow the hole and it does not grab or chew up the hole.
    Steve knight
    cnc routing

  14. #14
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    Quote Originally Posted by Anthony Whitesell View Post
    You didn't mention two things in your original message. 1-hand drill, no drill press, and 2- using forstner bit.
    I'm just wondering why you need to use a forstner bit, are you not wanting to drill completly through the material?

    If so, I would think the only way to solve the problem is to plug the existing hole and redrill, as has been mentioned. If you are drilling through the material, get yourself a hole saw kit and double up a 3/8" bit and a 1/2' bit and use the 3/8" bit as your guide through the existing hole while the 1/2" bit cuts the bigger hole.

  15. #15
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    Plug it and redrill with either a twist or brad point or forstner bit. Lot less messing around. Actually with a twist bit you don't have to plug it. Dick B.
    Last edited by Dick Bringhurst; 03-02-2008 at 12:49 AM.
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