Left hand drill bit??

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  • RPease
    Senior Member
    • Dec 2001
    • 506

    Left hand drill bit??

    OK...........I've got to ask............is there some "special" reason for having a left handed drill bit.

    I saw some advertised and cannot figure out what they would be good for except for a broken drill that will "only" work in reverse........

    A "hole" is a "hole".......whether drill clockwise or counter clockwise.........Right??

    Can someone explain what they are for??

    Thanks.............
    RPease
  • Buzzer John
    Member
    • Jan 2006
    • 56

    #2
    one use for left hand bits is when you are drilling out a broken off bolt. A right hand bit will try to screw it in further, while a left hand one tends to unscrew it. If you are lucky (seldom happens) the broken bolt might come out when you drill with the LH bit.
    I think there is another use, but can't think of it right now. John

    Comment

    • Mark Hockett
      Senior Member
      • Apr 2001
      • 976

      #3
      They are used for removing broken bolts. By drilling in reverse when the drill bites at the end of the hole if will spin the bolt out instead of in.
      Mark Hockett

      Comment

      • oldtiffie
        Member
        • Nov 1999
        • 3963

        #4
        Left-handed drill bits

        They are of course rotated "back-wards" - true - no joke!!

        They are primarily for drilling out jammed or rusted bolts,studs etc. They will sometime cause the thread to "walk out". The principle is the same as "screw extractors" - aka "Ezy-outs".

        It surprising how much concentration - for me anyway- when you've had a long time developing the skills and habits of sharpening right-handed drill bits!!

        Comment

        • Frank Ford
          Senior Member
          • Dec 2003
          • 1449

          #5
          I understand left hand drill bits are used in some multi-spindle drilling machines where the adjacent chuck have opposite rotation.
          Cheers,

          Frank Ford
          HomeShopTech

          Comment

          • loose nut
            Senior Member
            • Sep 2006
            • 6465

            #6
            Right hand drill bits for right handed people and left hand drill bits for left handed people, just like batters and golfers!!
            The shortest distance between two points is a circle of infinite diameter.

            Bluewater Model Engineering Society at https://sites.google.com/site/bluewatermes/

            Southwestern Ontario. Canada

            Comment

            • Duffy
              Senior Member
              • Jul 2007
              • 1784

              #7
              Left-hand drills are used in gang-drilling machines-particularly those used to drill those rows of holes in the side panels for adjustable shelving. Every other drill is left-handed and this elliminates the need for an idler gear between drills, and allows closer spacing with a simpler gear box. Duffy
              Duffy, Gatineau, Quebec

              Comment

              • Optics Curmudgeon
                Senior Member
                • Jul 2006
                • 913

                #8
                They are often used in the back side spindles of screw machines, for drilling the back of parts after they are cut off. I used to have a set of fraction and number lefties. Later, when I got to dealing with graduate students and PhD's they came in handy, just the thing to drive the "smart people" nuts. The time spent regrinding them was worth it.

                Joe

                Comment

                • KiddZimaHater
                  Senior Member
                  • May 2007
                  • 1843

                  #9
                  What about left-handed allen wrenches?

                  Comment

                  • gary55ford
                    Junior Member
                    • Dec 2007
                    • 13

                    #10
                    left handed drills

                    They are to drill holes for tapping left handed threads

                    Comment

                    • Weston Bye
                      Contributing Editor
                      • Jun 2002
                      • 4265

                      #11
                      Originally posted by Frank Ford
                      I understand left hand drill bits are used in some multi-spindle drilling machines where the adjacent chuck have opposite rotation.
                      Indeed, I have seen such creatures.
                      Weston Bye - Author, The Mechatronist column, Digital Machinist magazine
                      ~Practitioner of the Electromechanical Arts~

                      Comment

                      • RetiredFAE
                        Senior Member
                        • Jan 2006
                        • 307

                        #12
                        And here all this time I thought the left handed drill bits were for use south of the equator to counter act the Coriolis effect, you know, the way water swirls down the drain in a different direction down there, and that if you didn't use a left handed bit south of the equator, it would spin you into the ground.

                        And if you buy that, I have a big gold bridge I'd like to sell you too!
                        Steve
                        NRA Life Member

                        Comment

                        • sch
                          Senior Member
                          • Sep 2001
                          • 1258

                          #13
                          Left handed endmills are available for the same reason as Frank
                          Ford mentioned. Not for nothing are most single spindle mills
                          (as opposed to ganged mills) made with forward and reverse.
                          Steve

                          Comment

                          • oldtiffie
                            Member
                            • Nov 1999
                            • 3963

                            #14
                            Down under

                            Dead right Steve.

                            Its "different down-under".

                            If you are gunna get screwed here it will be with a left-hand thread.

                            We have a good line in gold-bricks too.

                            Comment

                            • wierdscience
                              Senior Member
                              • Jan 2003
                              • 22085

                              #15
                              Multi-spindle drill heads

                              I just need one more tool,just one!

                              Comment

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