"1/2 NPT" drill and tap sizes?

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  1. #1
    SupraForums Member Gadfly's Avatar
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    "1/2 NPT" drill and tap sizes?

    I need to drill and tap some 1/2 NPT holes, anyone know the drill and tap sizes?

    I asked the tool guy at Sears and he just looked at me like i had boobs on my forehead.

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    Kwan Jul Sul Freak Goldfinger911's Avatar
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    Technically a 1/2 NPT should be a 45/64" drill bit. However an 11/16" is the next closest I believe.

    Use this site fir a future reference.

    http://www.korit.com/tapndrill.htm
    __________________________________________
    Goldfinger911
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    SupraForums Member Gadfly's Avatar
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    wow, great site, thx

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    Republican Ckanderson's Avatar
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    most taps have the proper drill bit size stamped into them FYI

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    SupraForums Member Gadfly's Avatar
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    yeah, but i need to find/nuy the tap

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    SupraForums Member lambchop11078's Avatar
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    When I got my 1/2 NPT tap, the recommended drill bit size listed was 23/32. I had no luck finding that size so I used a 11/16.

  8. #7
    How does my exhaust smell Bad4URHeart's Avatar
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    The correct bit for any tap should be 90% of the tap size.

    NPT requires an 50% increase adjustment since it is measured differently than drill bits.

    Therefore, 1/2 * 1.5 (50% increase) = 0.75
    0.75 * 90% (tap to drill bit conversion factor) = 0.675

    Drill bit sizes in that range
    21/32 = 0.6563
    11/16 = 0.6875
    23/32 = 0.7188

    11/16 is the closest and the correct size for that tap.

  9. #8
    SupraForums Member Gadfly's Avatar
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    Where did you buy the tap?

  10. #9
    backpsi is my batsignal!!
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    45/64

    http://www.fastenal.com/web/products...ex?sku=0354974

    i always deal with them for hard to find measurements on drill bits and taps. That how i bought the 10.8 MM drill bit and the 12mm x 1.25 tap
    Last edited by figgie; 01-04-2006 at 01:58 PM.

  11. #10
    Moderator Jim Swantko's Avatar
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    Quote Originally Posted by Gadfly

    I asked the tool guy at Sears and he just looked at me like i had boobs on my forehead.

    Do you? Pics?

  12. #11
    How does my exhaust smell Bad4URHeart's Avatar
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    a 17mm drill bit will also work!

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    ?!!?HABBA BABBA??!! 93civEJ1's Avatar
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    ok...so I think I can find the 11/16 drill bit....where can I find the tap?

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    backpsi is my batsignal!!
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    wow so much for people reading the thread!

    http://www.supraforums.com/forum/sho...97&postcount=9

  15. #14
    ?!!?HABBA BABBA??!! 93civEJ1's Avatar
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    Quote Originally Posted by figgie View Post
    wow so much for people reading the thread!

    http://www.supraforums.com/forum/sho...97&postcount=9
    wow, so much for trying to own some one.

    They dont have that there anymore.

    AND i meant like a local chain store. Lowes, Homedepot, Sears, etc.

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    SupraForums Member Josh S's Avatar
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    I just got the tap and drill bit from http://www.wttool.com/
    I only needed to do a few holes so I didn't really care about getting very high quality, but their the tap and drill worked great for me.

  17. #16
    backpsi is my batsignal!!
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    Quote Originally Posted by gothaimviii View Post
    wow, so much for trying to own some one.

    They dont have that there anymore.

    AND i meant like a local chain store. Lowes, Homedepot, Sears, etc.
    seems like you are strong on the fail side....



    45/64" drill bit

    http://www.fastenal.com/web/products...ex?sku=7006341
    http://www.fastenal.com/web/products...ex?sku=0316247

    11/16"

    http://www.fastenal.com/web/products...ex?sku=0356448

    took me all of 30 seconds to search for those.

    As for local. Why would anyone of those chains carry something like that? Hydraulic shop PERHAPS. And you ARE aware that FASTENAL does have store fronts?

    (search again.... EUREKA!)


    Just in TN

    http://www.fastenal.com/web/location...&zip=&state=TN

    3 pages worth of 20 entries each.
    official translator for Canuck-istan...
    Cocaine is one hell of a drug...

  18. #17
    Inline for the win Suprafied's Avatar
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    McMaster or Traver's is your friend....

    DP

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