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Thread: helicoil fight

  1. #21

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    Grinding the drillbit in this manner will prevent grabbing. Not as nice as a reamer but will work.

  2. #22
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    Good suggestion Larry, I was taught to do that when drilling brass.
    Bob Rice #6738
    He that conquereth his own soul is greater than he who taketh a city.

  3. #23

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    Brass and plastic.

  4. #24
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    I can't quite tell what you did there Larry.What surface is ground? Is this is?661631.jpg Like the one on the right correct?
    Last edited by DCoul; 10-24-2017 at 05:04 PM.

  5. #25
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    Just web-search "drill bit angles", Folks!

    Wikipedia has a handy chart for different materials, if you missed it in your highschool text book.

    ....Cotten
    PS: I thought everybody had seen toys like these...
    Attached Images Attached Images
    Last edited by T. Cotten; 10-24-2017 at 03:57 PM.
    AMCA #776
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  6. #26
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    I bought a Sawzall quite a few years ago and my wife says " don't you have enough tools..."? Uh, no.

  7. #27
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    Quote Originally Posted by DCoul View Post
    I bought a Sawzall quite a few years ago and my wife says " don't you have enough tools..."? Uh, no.
    DCoul!

    Next time, remind her that the most important tools are the ones that make more tools.

    Hopefully, she will see the 'economics'.

    ...Cotten
    Last edited by T. Cotten; 10-24-2017 at 05:42 PM.
    AMCA #776
    Dumpster Diver's Motto: Seek,... and Ye Shall Find!

  8. #28
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    Quote Originally Posted by DCoul View Post
    I can't quite tell what you did there Larry.What surface is ground? Is this is?661631.jpg Like the one on the right correct?
    Not to speak for Larry which brought up the good point (no pun), the leading (or cutting) edge is dulled or given a negative rake. To explain negative and positive rake is easiest when thinking of a lathe tool, the cutting point is on center but the chip flow is either downward (positive) or upward (negative). It is the way the insert or cutting tool is positioned. With a drill the lead cutting edge is against the chip flow, I guess that is a way to explain it, so it doesn't dig or draw itself into the work piece. Larry, I didn't mean to answer for you and correct me if I'm wrong or if different from your knowledge.
    Bob Rice #6738
    He that conquereth his own soul is greater than he who taketh a city.

  9. #29
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    Like this?polyc6.jpg

  10. #30
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    I don't want to speak for Larry either,...

    And I couldn't copy his pic for an arrow either, so I have attached my own.

    I hope I am correct that Larry wanted to illustrate a chip-breaker-grind shown on the right in my attachment upon a tortured Caterpillar bit.

    Its ugly, probably hand-carved, but graphically demonstrates the technique.

    ....Cotten
    Attached Images Attached Images
    Last edited by T. Cotten; 10-24-2017 at 06:58 PM.
    AMCA #776
    Dumpster Diver's Motto: Seek,... and Ye Shall Find!

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