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  1. #1
    Gold Member BTackett's Avatar
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    Knoxville, Tn

    Default Tap/thread sizes

    I am looking to drill/tap some M12 bolt holes on the hub of my Mits and wondering if I were going to drill/tap for a 1/2" bolt what size drill bit to use? Reason I am drilling is 4 of the 6 are already crossed. looks like someone tried already to use a standard bolt on Metric threads.

    Also, what size to drill/tap to 5/8" bolt?
    I found an old chart but it only shows up to 3/8 size.




    thanks,

    Bill

  2. #2
    Silver Member Grand_Pooba's Avatar
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    Apr 2007
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    166
    Location
    Wyoming County, NY
    Tractor
    Bobcat CT230 & John Deere X324

    Default Re: Tap/thread sizes

    I don't think you will be able to use the 1/2 because the tap drill is smaller than 12mm. The tap drill for a 5/8-11 is a 17/32" (.5312). A 9/16-18 (.515 tap drill) would work too but it's a bit of an odd ball size. Hope that helps
    Steve

  3. #3
    Platinum Member bjcsc's Avatar
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    Feb 2007
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    559
    Location
    Johns Island, SC
    Tractor
    JD 5225, JD 555B

    Default Re: Tap/thread sizes

    Here's a chart...

  4. #4
    Silver Member Mundy's Avatar
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    Nov 2007
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    112
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    Swartz Creek, Michigan
    Tractor
    Satoh Beaver 4X4, Scag Super Z

    Default Re: Tap/thread sizes

    Just a suggestion, If the whole tractor is metric I would keep it that way.

    If you change some to standard yes you solve the problem today, but if in the future you or another owner have to replace those bolts for some reason or even just disassemble reassemble it complicates things when some are standard and some are metric.
    http://Crestwoodscorsos.com
    Regards,
    Mundy


    If they outlawed guns could we use swords?

  5. #5
    Veteran Member
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    Jul 2005
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    1,302
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    lower part of Md.
    Tractor
    JD310, ASV RC-100

    Default Re: Tap/thread sizes

    and another http://www.imperialinc.com/pdf/I_Dri...DrillChart.pdf

    I have one of these laminated and stuck to the wall next to the drill press

  6. #6
    Gold Member BTackett's Avatar
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    Default Re: Tap/thread sizes

    tlbuser, I now have one of those laminated on my wall! thanks

    I normally would not change std to metric but apparently the previous owner decided to do that with the left wheel and then used smaller longer bolts on the right side with washers/nuts on the back side. Not good. So , If I re-thread the right side back to metric and the left side is larger than M12 (5/8") then I would have std/metric rear wheel bolts. I just want to make both sides the same regardless.

    thanks for the replies.

    Bill

  7. #7
    Silver Member Mundy's Avatar
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    Nov 2007
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    Location
    Swartz Creek, Michigan
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    Satoh Beaver 4X4, Scag Super Z

    Default Re: Tap/thread sizes

    That makes sense. You are correcting the problem I was thinking you were going to create. All lug nuts the same is all the same wheather metric or standard.

    Good luck
    http://Crestwoodscorsos.com
    Regards,
    Mundy


    If they outlawed guns could we use swords?

  8. #8
    Gold Member
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    Aug 2005
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    333
    Location
    NW Pa.
    Tractor
    Kubota L3400

    Default Re: Tap/thread sizes

    Take one of the un-damaged bolts with you to a automotive store.

    match it to a "Heli-coil" kit. A little expensive but it will be a professional / original repair. Also buy new bolts along with the kit.

    Thread Repair Kits - HeliCoil Threaded inserts for stripped threads, thread repair, stripped sparkplugs



    JW 5875

  9. #9
    Silver Member Grand_Pooba's Avatar
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    Location
    Wyoming County, NY
    Tractor
    Bobcat CT230 & John Deere X324

    Default Re: Tap/thread sizes

    Helicoils are good idea if you want to get back to the original bolt size (M12) but you'll have to drill and tap the holes to the lager size. I think it's M16 for the M12 helicoil so make sure you've got the right drill/tap on hand.

  10. #10
    Silver Member nate_m's Avatar
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    Jan 2008
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    Location
    South West OHIO
    Tractor
    JD 2520

    Default Re: Tap/thread sizes

    A good rule to remember for Metric Bolts:

    Subtract the pitch from the diameter to get drill size.

    For example, the appropriate drill for an M6 x 1.0 would be 5.0mm.

    Of course, most of us don't have metric drill bits lying around, so you still need the chart next to the drill press to find the equivalent Americaneze size drill bit...
    ~Nate

    JD2520

    "I'm not your ordinary, everyday fool." - Clark W. Griswold.

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