Thread: Tapping holes

  1. #1
    So I have a fuck tonne of M3 holes to tap.

    Are there taps out there that tap really close to the bottom of the hole?
    Most of the taps that I have found are for through hole not really bottoming out.

    I know there are "bottom" taps but they still leave quite a bit at the bottom of the hole left to thread.

    Any ideas?
    Derby MakerSpace coming soon! >> https://derbymaker.space/

  2. #2
    You can knock most of the point off a spiral flute tap without affecting it's function. In this way you can get close enough for finishing off with a custom trimmed bottom tap with reduced lead-in to finish the thread with as much profile as possible as close as possible to the bottom of the hole, if you want more thread closer to the bottom trim the bottom tap further and run it to the bottom of all the holes again.
    I Thread Mill down to M3 but I wouldn't want to do a shit-load that way ;-)
    You think that's too expensive? You're not a Model Engineer are you? :D

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  4. #3
    Quote Originally Posted by magicniner View Post
    You can knock most of the point off a spiral flute tap without affecting it's function. In this way you can get close enough for finishing off with a custom trimmed bottom tap with reduced lead-in to finish the thread with as much profile as possible as close as possible to the bottom of the hole, if you want more thread closer to the bottom trim the bottom tap further and run it to the bottom of all the holes again.
    I Thread Mill down to M3 but I wouldn't want to do a shit-load that way ;-)
    Good idea! Ill give that a go with a spare tap.
    Derby MakerSpace coming soon! >> https://derbymaker.space/

  5. #4
    As above I tend to just take an angle grinder to a plug tap... obviously you don't want to take the whole tip off but you don't need the point that most smaller taps come with.

    Assuming this is in alu given your projects, the screw itself will happily make the last tiny bit of the thread itself too.

  6. #5
    It's easy to work out, compare the initial and plug taps, you want the plug tap to be able to take up the work where the initial tap left off.
    You think that's too expensive? You're not a Model Engineer are you? :D

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