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"3-egde" drills

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  • #16
    Well, all you need to do is resharpen them with a normal point.

    They sound like a gizmo to me. Just something to attract attention and generate more sales. From the photos it appears to be a split point drill where the primary, cutting edge has been divided into three steps. They do not say what, if any, advantage this provides. I would think it would have the normal centering advantages of a split point grind which keeps the bit on the punch mark better. And I would think that the chips coming off the edges would be divided into three separate and smaller(narrower) chips. I think the B&D bullet drills would do much the same thing with an easier geometry to create if you are resharpening them.

    I am wondering what would happen if you used one of those drills on sheet metal, even with a good, solid backing material.





    Originally posted by epicfail48 View Post
    Good lord i absolutely hate those damn things. My boss at work decided to get a set of DeWalt branded ones, absolutely freaking horrible. The theory is that the smaller diameter acts as a pilot for the larger and cuts down the power needed (? Marketing crap). In reality all it does it make the drills really like catching and snapping
    Paul A.
    SE Texas

    And if you look REAL close at an analog signal,
    You will find that it has discrete steps.

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    • #17
      Spade drills with changeable inserts that had such lips were described as "serrated".

      Sarge41

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      • #18
        Originally posted by sarge41 View Post
        Spade drills with changeable inserts that had such lips were described as "serrated".

        Sarge41
        They were basically made with the segments between the slits or small notches all along the same line though. Perhaps aimed more at chip control to break up the chips?
        Chilliwack BC, Canada

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        • #19
          Originally posted by 754 View Post
          Chip control is a great thing..
          Amen.
          Chip breakers it would appear, much like they are ground in some keyway broaches.

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          • #20
            They look like someone is trying to get them to work like a step drill? the 2 flutes would make them hard to use vs the unibits.

            Click image for larger version

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            Your right guys, after a first grinding it's all gone.

            TX
            Mr fixit for the family
            Chris

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            • #21
              That is what I never understood about yellow coated drills, it only good till you sharpen.... but then it finally hit me, the weekend warriors don't sharpen, they just buy another one, then they often over speed it...... no skill, no theory, no hope..

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              • #22
                Originally posted by 754 View Post
                That is what I never understood about yellow coated drills, it only good till you sharpen.... but then it finally hit me, the weekend warriors don't sharpen, they just buy another one, then they often over speed it...... no skill, no theory, no hope..
                I mean, you can say the same about coated end mills too. Think its more trickle-down from the industry, the coatings make the job go better and in volume it doesnt make sense to resharpen, since the coatings work they get popular and passed down to hobbyists

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