M5x.5 tap drill size?
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    Default M5x.5 tap drill size?

    Anyone know the drill size for the m5x.5 its not listened on any chart I've been able to find

    Sent from my SM-G973U using Tapatalk

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    Good rule of thumb that works pretty well for metric taps is take the tap size and subtract the pitch to get the tap drill size. So a 4.5mm drill in your case.

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    Quote Originally Posted by Erstwhile View Post
    Anyone know the drill size for the m5x.5 its not listened on any chart I've been able to find

    Sent from my SM-G973U using Tapatalk
    For a guide you can ...let's use a 1/4-20 for example. Take .250 and subtract depth per revolution which in this case is .05 (1÷20) . Take .250 - .050 gives you a drill size of .200

    Do the math on any tap size and will get you within .001 of what it calls for.

    Sent from my SM-G950U using Tapatalk

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    Quote Originally Posted by BugRobotics View Post
    Good rule of thumb that works pretty well is take the tap size and subtract the pitch to get the tap drill size. So a 4.5mm drill in your case.
    Exactly this. In less words

    Sent from my SM-G950U using Tapatalk

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    best and only way is to look up the Minor dias for that thread and use that. there is no other substitute,

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    Quote Originally Posted by Delw View Post
    best and only way is to look up the Minor dias for that thread and use that. there is no other substitute,
    Just curious... for just say a 1/4 20 2A you would use less than a .190?? I feel like I would be breaking alot of taps??

    Sent from my SM-G950U using Tapatalk

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    Quote Originally Posted by tobydbaker74 View Post
    Just curious... for just say a 1/4 20 2A you would use less than a .190?? I feel like I would be breaking alot of taps??

    Sent from my SM-G950U using Tapatalk
    I would hope not, considering the minor dia for a 1/4-20(which is a 2b not a 2a btw) is max.207- min.196

    where did you come up with that number?

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    Quote Originally Posted by tobydbaker74 View Post
    Just curious... for just say a 1/4 20 2A you would use less than a .190?? I feel like I would be breaking alot of taps??

    Sent from my SM-G950U using Tapatalk
    Quote Originally Posted by Delw View Post
    I would hope not, considering the minor dia for a 1/4-20(which is a 2b not a 2a btw) is max.207- min.196

    where did you come up with that number?
    oh forget it, you looked at the external thread data on a 1/4-20 thread and came up with your number which is a .1894 Max minor Dia.
    FYI there is a huge difference between external data on thread and internal data on a thread. This is why you have to pay attention to what your looking at,

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    according to machinerys handbook

    M5 coarse ...drill 4.2mm recommended gives 81 percent engagement

    or 4.3 giving 71 percent engagement

    does not state the pitch though only coarse thread.

    if its fine metric fine then it no applicable to that.

    i just checked the chart i have P and N chart

    lists coarse as 5 x 0.8 so no good to you in regard to the above information

    need to keep looking, ring up the tap supplier to see maybe the best bet

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    m5 x0.5 6h is
    max minor 4.599 ie .1811
    min minor 4.459 ie .1756

    They got aps for phones and computers everywhere even free, or you can just type it up in a yahoo or google

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    Quote Originally Posted by Delw View Post
    oh forget it, you looked at the external thread data on a 1/4-20 thread and came up with your number which is a .1894 Max minor Dia.
    FYI there is a huge difference between external data on thread and internal data on a thread. This is why you have to pay attention to what your looking at,
    Yes you are correct I'm getting old and looked at the wrong chart.

    Sent from my SM-G950U using Tapatalk

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    Quote Originally Posted by BugRobotics View Post
    Good rule of thumb that works pretty well for metric taps is take the tap size and subtract the pitch to get the tap drill size. So a 4.5mm drill in your case.
    .
    i believe thats for 75% thread and yes its commonly done. just look at tap drill chart, usually tap drill size is close to that rule of thumb. drill bits can easily drill oversize especially if badly sharpened. just saying 4.5mm drill "might" drill bigger than 4.5mm. fine threads got to watch for that even more

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    BugRobotics got it, see image from DC Swiss site- but I will second what Tom said about accurate drill size, you can lose a lot of thread if your drill goes oversize just a little at a fine pitch like that.

    mf5.jpg

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    Quote Originally Posted by Screwmachine View Post
    BugRobotics got it, see image from DC Swiss site- but I will second what Tom said about accurate drill size, you can lose a lot of thread if your drill goes oversize just a little at a fine pitch like that.

    mf5.jpg

    Thats why some people call it hole size perhaps ??

    Peter

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    Quote Originally Posted by BugRobotics View Post
    Good rule of thumb that works pretty well for metric taps is take the tap size and subtract the pitch to get the tap drill size. So a 4.5mm drill in your case.
    I'm assuming this is for cut taps. How would this rule of thumb look for roll or form taps?

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    Quote Originally Posted by BugRobotics View Post
    Good rule of thumb that works pretty well for metric taps is take the tap size and subtract the pitch to get the tap drill size. So a 4.5mm drill in your case.
    The wonderful world of metric threads. It doesn't just work for taps. Boring for an M80x2 thread? Ø78 will do just fine

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    Quote Originally Posted by tonymor View Post
    The wonderful world of metric threads. ......
    Same rule works for any 60 degree thread, metric or imperial. I haven't used a tap drill chart in 40+ years since learning this little tidbit.

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    not only a badly sharpened drill but a drill bit that hit a hard spot of slag can get damaged and drill oversized holes.
    .
    i have even seen carbide drill damaged drill holes .040" oversize before. usually its best to inspect parts and look at threads and see if internal threaded holes look ok or that look like a oversized drill was used. worst case is to have damaged drill with 60 minutes tool time left, drill hundreds if not 1000's of oversized holes on many many parts.
    .
    most blow out holes and what better time than to look at threaded holes right after ? I never assume drilled holes is same size as drill bit from decades of experience.

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    Quote Originally Posted by Nibleswick View Post
    I'm assuming this is for cut taps. How would this rule of thumb look for roll or form taps?
    Pitch diameter plus a few thou.

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    Quote Originally Posted by Nibleswick View Post
    I'm assuming this is for cut taps. How would this rule of thumb look for roll or form taps?

    Take the tap size and subtract 1/2 the pitch.

    Check out the tap charts. The ones I checked all followed that formula


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