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Thread: Drilling round stock on center

  1. #1
    Join Date
    Dec 2004
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    Question Drilling round stock on center

    I know this must be a simple operation but for a greenie. Here is my challenge. I need to drill a hole using a #42 drill into the side of round stock and have it centered. Please help.

  2. #2

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    What equipment do you have?

    It's best done on a milling machine using an edge finder to find the side of the round stock, then moving one half the diameter of the EF + one half the diameter of the stock. That puts the spindle directly over the center of the stock.

    If that much accuracy isn't needed, you can get or make a drilling jig with a hole centered in a V-groove.


    Oops, that'll put the hole in the top of the round stock, not the side. Sorry about that.
    Last edited by winchman; 12-22-2011 at 02:49 PM.

  3. #3
    Join Date
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    You can use the 'ruler trick'.

    1) Put the work in a vice, positioned under the drill or mill spindle.
    2) Put a sharp pointed rod (like the shaft of a nail) in the chuck.
    3) Place a double edge razor blade over the work, and bring the tip of the rod down on it.

    Move the vise until the blade is horizontal. When the blade is at 90 degrees to the rod, it is close to being perfectly centered. Lock the vise down, replace the rod with a drill and go for it.

    Dan
    Measure twice. Cut once. Weld. Repeat.
    ( Welding solves many problems.)

  4. #4
    Join Date
    Apr 2011
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    South Louisiana
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    Thumbs up

    Like Winchman said. Touch off on the side of round stock with the side of your drill bit. Move 1/2 your tool plus 1/2 your stock and you will be in the center.

    1/4"=.250/2=.125

    #42=.0935/2=.04675

    .125+.04675=.17175 or rounded .172

    I would use a small center or spot drill to start the hole. You can touch off with anything you want to get to the center. Center is center.

    Define "side" of your round stock.

  5. #5
    Join Date
    Mar 2010
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    Chicago, IL
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    Default

    Quote Originally Posted by H380
    I would use a small center or spot drill to start the hole.
    Follow that advice. When drilling into a curved workpiece, your twist drill bit will wander on engagement--guaranteed. A spot drill with an angle at least that of your drill bit is best. Spot drill to roughly the full diameter of the hole you want to drill. Follow with the standard twist drill. I realize this is a fairly small drill bit on a fairly small workpiece, so I will mention the other option is to use a drill bushing to guide your drill bit into the workpiece. Here is a nice little primer: http://tinyurl.com/6s4buz7

  6. #6
    Join Date
    Jul 2009
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    SF bay area, CA
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    Default

    Quote Originally Posted by winchman

    It's best done on a milling machine using an edge finder to find the side of the round stock, then moving one half the diameter of the EF + one half the diameter of the stock. That puts the spindle directly over the center of the stock.
    Rather, I think it would be more accurate to edge find BOTH vise jaws and then move to the middle.

  7. #7
    Join Date
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    Albuquerque
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    And if youre holding it with two [Matched] V blocks use the inside
    edges of the V blocks to edge find on and divide by two for the centre.
    ...lew...

  8. #8
    Join Date
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    Live Oak, TEXAS
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    If the hole doesn't need to be "EXACTLY" on center, (say within .005-.010), then use one of these: They work great for a quick & dirty center-find on any round stock.
    $5.00 at any online supply.

    ...
    If the hole needs to be 'EXACTLY" on center (within +/- .002), then edge-find the back vise jaw, and move over 1/2 the work diameter.
    As said before, use a spot drill or center drill first, to guide your drill.

  9. #9
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    Winnipeg Manitoba
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    Theoretically, crotch center in tailstock, bit/chuck other end (collet held, 3/32" or so?), wouldn't vouch for accuracy though...self-centering vice mill or drill press...depends on equipment and accuracy needs

  10. #10
    Join Date
    Aug 2008
    Location
    Kansas
    Posts
    121

    Default

    Quote Originally Posted by KiddZimaHater
    If the hole doesn't need to be "EXACTLY" on center, (say within .005-.010), then use one of these: They work great for a quick & dirty center-find on any round stock.
    $5.00 at any online supply.

    ...
    If the hole needs to be 'EXACTLY" on center (within +/- .002), then edge-find the back vise jaw, and move over 1/2 the work diameter.
    As said before, use a spot drill or center drill first, to guide your drill.
    You know, I never knew such a tool existed, but now that I do, I need one!

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