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Single pointing 0-80 internal thread

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  • #31
    That may be an urban legend. My father told me that the Russians (USSR) sent a tiny screw to Switzerland, expecting them to be awestruck. It was sent back to them with no comment. Ivan replied, "What did you think about that?". The Swiss replied, "Look at it closely". They had bored a hole through it (and possibly tapped it as well). This was in the late 50s or 60s, IIRC.

    These are variations on similar exchanges, going back even to 300 BC, according to Snopes.
    http://pauleschoen.com/pix/PM08_P76_P54.png
    Paul , P S Technology, Inc. and MrTibbs
    USA Maryland 21030

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    • #32
      Originally posted by 90LX_Notch View Post

      Matt- The lathe is a 618 Square head. They changed over to this style in the early 1970's.

      -Bob
      ah, gotcha, thought a few things looked different

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      • #33
        Atlas / (Craftsman) went from Bronze Bearing Head-stocks to Timken Bearing head-stocks and the Head-stock became a square casting (More Modern ) at that time .
        Also changed the spindle thread (larger to 1" ? ) as I recall
        Rich
        Green Bay, WI

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        • #34
          How fast did you turn it? The major diameter of a number screw is .013 X # + .060 (I have no idea why I remember this)
          At a reasonable 30 sfm for HSS the spindle speed is 1900 rpm's at .060" diameter.

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          • #35
            The SFM is just a guideline for optimal productivity and tool life, especially for HSS. You can turn the spindle by hand if you wish. This may not apply to carbide, however, and high surface speed may result in a better finish.
            http://pauleschoen.com/pix/PM08_P76_P54.png
            Paul , P S Technology, Inc. and MrTibbs
            USA Maryland 21030

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            • #36
              Originally posted by PStechPaul View Post
              The SFM is just a guideline for optimal productivity and tool life, especially for HSS. You can turn the spindle by hand if you wish. This may not apply to carbide, however, and high surface speed may result in a better finish.
              Carbide is not any different, works also at sloow speed. There is actually a mid-speed range that often sucks and going either way improves your results.

              I used carbide tooling to turn the 0.014mm or 5 "tenths" shaft shown in the microscope thread.
              Even at 4000rpm that works out to roughly zero SFM

              I'm affraid I'm not able to match up OP's internal thread.. even if I have the 127TPI screw already done:
              https://bbs.homeshopmachinist.net/fo...threads-127tpi

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