Tapping head for m3-m4 (1/8"-1/6")?


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Thread: Tapping head for m3-m4 (1/8"-1/6")?

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    Default Tapping head for m3-m4 (1/8"-1/6")?

    I'm going to cut a lot of m4 threads (also some m3) for my Kickstarter project: https://www.kickstarter.com/projects...r-edc-spinner/
    So far I've been cutting them by hand, but this won't be economical anymore so I'm going to buy a tapping head.
    Do you think I will be fine cutting m3-m4 threads with a tension compression tapping head into 6061 aluminum? The reversing tapping head by Procunier is a little bit too expensive for me.
    Any other suggestions or brands that offer good tapping heads?

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    Default Re: Tapping head for m3-m4 (1/8"-1/6")?

    T/C head will work fine. Make sure you get the correct type of tap.
    Spiral point for thru holes (pushes the chips down the hole), spiral flute for blind holes (pulls chips out like a drill does) or Form taps work great in aluminum and there are no chips.
    Don't use a straight flute hand tap, they are designed to have the chips stay in the flutes and come out with the tap. I've done it in a pinch but have to blow the chips off after every hole so not very efficient.



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    Default Re: Tapping head for m3-m4 (1/8"-1/6")?

    I was going to use form taps. I'm just worried that those small taps will break with a tension compression tapping head. Do you think I'll be fine?

    Another option would be to get a cheap ($170) noname reverse tapping head. Not sure what would be the best option...



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    Default Re: Tapping head for m3-m4 (1/8"-1/6")?

    A T/C head is no harder on the tap than a reversing tapping head. As long as you have enough extra depth in blind holes for the spindle to stop, and reverse, a T/C head will work just fine.

    There are three basic options for tapping heads:

    1) T/C - the simplest, cheapest and, arguably, the best option in most cases. The only down-side is, as mentioned, you need to allow plenty of extra depth in blind holes to ensure the tap NEVER bottoms out.

    2) Tapmatic, or generic Chinese reversing head - These work fine but are kind of a PITA to use. They are quite forgiving, as they will work fine even with non-optimal g-code. Like all reversing heads, you have to deal with securing the torque arm. These heads use a dog clutch, so engagement is rather brutal - they "bang" into engagement, and disengagement, whic can be hard on the tap. But, they do work, and are inexpensive. Tapmatics are smaller, and better made, than the generic Chinese heads, but functionally all are about the same, except for the reverse rate (Tapmatics are generally 1.5:1 reverse, while generics are generally 2:1 reverse).

    3) Procunier - the most elegant, but also most expensive option. Like all reversing heads, you have to deal with securing the torque arm. Procuniers use a conical friction clutch to engage and disengage, making them butter-smooth and near silent on engagement, which is much gentler on the tap. The one down-side (other than cost) is that they have NO ability to absorb overfeed. If you over-feed a Procunier, you WILL break the tap, if not the Procunier itself. Therefore, you MUST either KNOW the true spindle RPM, or intentionally under-feed when going down into the hole to ensure you NEVER, EVER over-feed.

    I have at least one of each type (generic Chinese, Tapmatic, Procunier, and T/C), and prefer the T/C for most operations. Also, the T/C is the ONLY one that can be used in an ATC. And, it's cheap enough, owning several is not an unreasonable cost burden.

    Regards,
    Ray L.



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    Default Re: Tapping head for m3-m4 (1/8"-1/6")?

    @Ray
    Thanks, that was exactly the information I was looking for. Just ordered the Tormach Modular T/C tapping head set



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    Default Re: Tapping head for m3-m4 (1/8"-1/6")?

    You should be fine with the T/C tapping head. I use the Tormach 32021 ER20 unit which is much cheaper than the 31807 modular unit. Below is a quick video that I made of testing a 8-32 form tap in 1/2-inch 6061 on my 770 when I first got the T/C head. A 8-32 screw is slightly larger than M4. Note that it is very important to use the tap drill recommended for your taps and material!





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    Default Re: Tapping head for m3-m4 (1/8"-1/6")?

    I use a T/C tapping head and I can make it work just fine with holes as small as 2-56.

    I have a formula that works for me, and so far (knock on wood) I haven't broken a tap yet.

    That formula is:

    1 inch divided by the pitch times 500 RPM

    Going into the hole, I reduce the feed rate my 10% for taps 8-32 and larger and 5% for taps 6-32 and smaller.

    At the bottom of the hole I tell the control:

    M4
    G4P.25

    Then G1 up at 10% faster than the calculated feed rate.

    I can't tell you why, but this formula works. I have tapped thousands of holes and I haven't broken a tap yet.



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    Default Re: Tapping head for m3-m4 (1/8"-1/6")?

    Quote Originally Posted by Steve Seebold View Post
    I use a T/C tapping head and I can make it work just fine with holes as small as 2-56.

    I have a formula that works for me, and so far (knock on wood) I haven't broken a tap yet.

    That formula is:

    1 inch divided by the pitch times 500 RPM

    Going into the hole, I reduce the feed rate my 10% for taps 8-32 and larger and 5% for taps 6-32 and smaller.

    At the bottom of the hole I tell the control:

    M4
    G4P.25

    Then G1 up at 10% faster than the calculated feed rate.

    I can't tell you why, but this formula works. I have tapped thousands of holes and I haven't broken a tap yet.
    I fail to see the logic of your 5% and 10% feed modifications. In BOTH cases, you are forcing the T/C holder to extend as the tap is moving, which risks reaching the end of its extension travel. What is the logic there? And what on earth is the logic of using different values for smaller taps? It may work, but makes absolutely no sense whatsoever.

    Regards,
    Ray L.



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    Default Re: Tapping head for m3-m4 (1/8"-1/6")?

    I have no idea why it works, but..

    A consistent load or bias up or down might perhaps make sense on less than perfect machines.
    This could take out any slack on z and always downwards ?
    It might eliminate any up/down slack ?

    Just comes to mind.
    Quote Originally Posted by SCzEngrgGroup View Post
    I fail to see the logic of your 5% and 10% feed modifications. In BOTH cases, you are forcing the T/C holder to extend as the tap is moving, which risks reaching the end of its extension travel. What is the logic there? And what on earth is the logic of using different values for smaller taps? It may work, but makes absolutely no sense whatsoever.

    Regards,
    Ray L.




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    Default Re: Tapping head for m3-m4 (1/8"-1/6")?

    The idea is to adjust teh tap feed slightly slightly going down to slightly compress teh tap so that when teh overrun occurs at teh end of stroke that teh tap will be back at center when it starts back up. The end result is to have teh tap center of teh T/C range (neutral) when the tap reaches teh top of stroke. IF it is extended it tends to rip out teh last part of teh thread (spring pressure) and if compressed it mars up teh last thread as it retracts clear.

    Just a thought, (;-) TP



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    Default Re: Tapping head for m3-m4 (1/8"-1/6")?

    I can see how having the tap in tension when it comes out of the hole would be better than in compression, especially in hard materials.



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    Default Re: Tapping head for m3-m4 (1/8"-1/6")?

    I've used a form tap to thread 3-48 blind holes in aluminum with the Tormach T/C (basic model) and had no problems at all so I don't think that M3 or M4 holes will be a problem. Don't forget that form taps need a *larger* hole than spiral point or flute taps.

    Last edited by MichaelHenry; 02-16-2017 at 12:05 PM. Reason: corrected technical error


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Tapping head for m3-m4 (1/8"-1/6")?
Tapping head for m3-m4 (1/8"-1/6")?