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Tapped Holes

  1. Dec 30, 2006 #1
    I just want to clarify. A tapped hole is basically a hole that has been threaded for a bolt. Is this correct?

    So would a tapped M6 hole be 6mm in diameter for a 6mm diameter bolt?

  2. jcsd
  3. Dec 30, 2006 #2


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  4. Dec 30, 2006 #3


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    Wait, are you asking what size hole to drill that will then be tapped for an M6 bolt? Then that's not 6 mm, and it also depends on the number of threads on your bolt. You need a chart of tap drill sizes like this
    which also gives you clearance hole sizes.
    Last edited by a moderator: Apr 22, 2017
  5. Dec 30, 2006 #4


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    You're right that a tap drill is smaller than the nominal call out diameter on any tapped hole, but that's not what the OP is asking. In an M6 the major diameter of the thread is 6mm. I would just be certain that the OP realizes that if they take a set of calipers or mics to the hole, they will be measuring the minor diameter and thus gtting the tap drill size.
  6. Dec 30, 2006 #5
    depends if the unthreaded part of the bolt also needs to be in the hole
    then you need two drills a smaller one for the part the threads are cut in
    and a true 6mm for a redrill of the unthreaded upper part
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