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35315Re: [MILL_DRILL] how to drill deep holes

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    Feb 2, 2014
      In article <1391314173.63870.YahooMailNeo@...>,
      Tom Curlee <tcurlee@...> wrote:
      > - Start the hole with a center drill.
      > - Drill the hole with a short shank drill (screw machine bit?).
      > - Deepen the hole with a normal length bit.
      > - Finish the hole with a long shank or spade bit.

      That is the normal procedure. When you've used your "long" bit you move to
      the "extra long" series.

      Interestingly, anything deeper than three times the drill diameter is
      considered a "deep" hole", though I think most of us would cheerfully
      drill almost to full flute depth without much thought.

      Stuart Winsor
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