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  1. #1
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    Default Threadforming Stressproof

    I have a tendency to break spiral flute taps in stressproof, always on retract in the lathe. I think the material's chip nature is the cause.

    Regardless, I gotta do it. So how well do form taps do in this material? The threads are solely for fixturing so no crazy specs other than don't break off the tap.

    Tips, tricks?

    Edited for clarity.

    Sent via CNC 88HS
    Last edited by Cole2534; 02-03-2021 at 10:56 AM.

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    Use a gun tap. Drill a larger hole for 50% threads. Use sharp tap. Use dark thread cutting oil. If tapping deep clear chips half way.

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    Quote Originally Posted by Cole2534 View Post
    I have a tendency to break cut taps in stressproof, always on retract in the lathe. I think the material's chip nature is the cause.

    Regardless, I gotta do it. So how well do form taps do in this material? The threads are solely for fixturing so no crazy specs other than don't break off the tap.

    Tips, tricks?

    Sent via CNC 88HS
    I have no experience with this material, but when I am having issues tapping lower quantity stuff, I just opt to use a thread mill. If you have the ability (y axis), it may save you a bunch of headaches.

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    Stressproof doesn't like to be cold worked.

    Good luck,
    Matt

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    I used to do a pile of 1/4-20 and 5/8-11 in stressproof. I used a dab of Moly-Dee in each hole, 1/4 at 500 RPM and 5/8 at 200 worked fine. A fast reverse seems to help.

    Ed.

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    Quote Originally Posted by Matt_Maguire View Post
    Stressproof doesn't like to be cold worked.

    Good luck,
    Matt
    That's exactly what I was anticipating.

    Sent via CNC 88HS

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    Quote Originally Posted by Cole2534 View Post
    I have a tendency to break cut taps in stressproof, always on retract in the lathe.
    What kind of cut taps are you using? Spiral point? Spiral flute? How deep are you tapping?

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    Quote Originally Posted by Mtndew View Post
    What kind of cut taps are you using? Spiral point? Spiral flute? How deep are you tapping?
    Spiral flute. 1/4-20, 1/2" deep threads, 1" deep hole.

    Ended up drilling to 1-1/4" deep with a #6 and had no issues usong a spiral point.
    Sent via CNC 88HS

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    Quote Originally Posted by Cole2534 View Post
    Spiral point. 1/4-20, 1/2" deep threads, 1" deep hole.

    Ended up drilling to 1-1/4" deep with a #6 and had no issues.
    Spiral point taps are for through holes; they shoot the chips forward. Spiral flute taps are much better for blind holes.

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    Quote Originally Posted by DanielG View Post
    Spiral point taps are for through holes; they shoot the chips forward. Spiral flute taps are much better for blind holes.
    I should have been more clear- I was breaking spiral flutes, the spiral point with extra depth lives.

    Sent via CNC 88HS

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    Quote Originally Posted by Cole2534 View Post
    I should have been more clear- I was breaking spiral flutes, the spiral point with extra depth lives.

    Sent via CNC 88HS
    At least by hand (don't have any real info), spiral flutes seem to require more torque so maybe that is a reason?

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    Quote Originally Posted by Mike1974 View Post
    At least by hand (don't have any real info), spiral flutes seem to require more torque so maybe that is a reason?
    I think they require more torque because they use what's essentially a bottoming chamfer length to get the chips formed in a way that (ideally) they flow up the flutes - bigger, fewer chips.

    A more traditional chamfer length like on a spiral point would give more, thinner chips, making it easier to clog the flutes.

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    Best way of answering your question is to buy a form tap and try it out.

    If it was me I'd use a spiral point tap and play with the hole dia and depth as you indicated in post #8 Also I'd use a coated tap, TICN coatings seem to work well.

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    Quote Originally Posted by DanielG View Post
    Spiral point taps are for through holes; they shoot the chips forward. Spiral flute taps are much better for blind holes.
    Spiral flute taps have a smaller cross section so are easier to break. I avoid using them, unless I really have to.

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    Quote Originally Posted by triumph406 View Post
    Spiral flute taps have a smaller cross section so are easier to break. I avoid using them, unless I really have to.
    They are excellent taps, as long as you don't need to tap very deep. Notice how every mfg's video only shows their spiral flute taps going minimal depth? Like who the hell is using a 1/2-13 bolt with 3/8" of thread?

    Once you go deeper than the flutes, chips like to wrap around the tap and that makes them snap in half.
    Great taps, limited usage unfortunately.

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    Quote Originally Posted by Mtndew View Post
    They are excellent taps, as long as you don't need to tap very deep. Notice how every mfg's video only shows their spiral flute taps going minimal depth? Like who the hell is using a 1/2-13 bolt with 3/8" of thread?

    Once you go deeper than the flutes, chips like to wrap around the tap and that makes them snap in half.
    Great taps, limited usage unfortunately.
    That's pretty much been my experience.

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    Quote Originally Posted by Mtndew View Post
    They are excellent taps, as long as you don't need to tap very deep. Notice how every mfg's video only shows their spiral flute taps going minimal depth? Like who the hell is using a 1/2-13 bolt with 3/8" of thread?

    Once you go deeper than the flutes, chips like to wrap around the tap and that makes them snap in half.
    Great taps, limited usage unfortunately.
    EXACTLY. With long, stringy chips it's less of an issue. With short, crumbly chips they pack the hole, IME, and block egress.

    Sent via CNC 88HS


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