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55 degree live center?

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  • 55 degree live center?

    I was looking for an MT2 bullnose live center for my lathe. Harbor Freight has their #40090 for $34.99... but the description says "cone angle: 55 degrees". There's no angle listed for their regular MT2 and MT3 live centers.

    Uh... all my center drills are 60 degrees, or so I thought. Does this look like a misprint, or are bullnose centers typically on 55 degrees?

    edit: hmm, I just found another one on eBay that says it's 70 degrees...
    Last edited by TRX; 03-23-2012, 01:02 AM.

  • #2
    That's a new one to me.
    It's only ink and paper

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    • #3
      If it is truly a "bullnose" center, you would need something like a number 34 center drill to get a hole big enough for the flat bullnose to fit into.

      They are meant for pipe and tubing that already has a hole.

      Dave

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      • #4
        I was just "assuming" you'd put a 60 degree internal chamfer in the workpiece if you could, to get something better than line contact.

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        • #5
          The steeper angle allows the use of a little less material to make the cone.

          "Line contact" in this application is not as bad as it may seem. It is usually on a relatively large diameter (more surface area even with a miniscule width), and in the case of pipe or tubing, relatively light weight workpieces.

          Dave

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