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Thread: Left hand drill bit??

  1. #1
    Join Date
    Dec 2001
    Location
    Missouri
    Posts
    506

    Question 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

  2. #2
    Join Date
    Jan 2006
    Location
    Lineboro, MD
    Posts
    54

    Default

    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

  3. #3
    Join Date
    Apr 2001
    Location
    Clinton, WA
    Posts
    955

    Default

    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

  4. #4
    Join Date
    Nov 1999
    Location
    SE OZ
    Posts
    1,966

    Default 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!!

  5. #5
    Join Date
    Dec 2003
    Location
    Palo Alto, California
    Posts
    1,276

    Default

    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

  6. #6
    Join Date
    Sep 2006
    Location
    Southwestern Ontario, Canada
    Posts
    3,242

    Default

    Right hand drill bits for right handed people and left hand drill bits for left handed people, just like batters and golfers!!

  7. #7
    Join Date
    Jul 2007
    Posts
    1,432

    Default

    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

  8. #8
    Join Date
    Jul 2006
    Location
    Livermore, California
    Posts
    712

    Default

    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
    NSA - the only government agency that actually listens to what you have to say.

  9. #9
    Join Date
    May 2007
    Location
    Live Oak, TEXAS
    Posts
    1,414

    Default

    What about left-handed allen wrenches?

  10. #10
    Join Date
    Dec 2007
    Location
    Ca.
    Posts
    13

    Default left handed drills

    They are to drill holes for tapping left handed threads

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