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  1. #11
    Join Date
    Jan 2016
    Location
    Ipswich & Southwold
    Posts
    853

    Default Re: Drilling out a bolt

    They do them in the workshop with a lefty drill or a thing that looks like a little 'easy out'.
    Electrics & electronics Suffolk & Southwold Boatyard
    Custom Panels + Eberspacher/Webasto

  2. #12
    Join Date
    Oct 2013
    Location
    Shropshire - Sundance, Bristol Channel
    Posts
    703

    Default Re: Drilling out a bolt

    New cobalt drill bit, slow and lots of lube, it'll go through it like butter. Being an allen key should be enough to guide it, get a pilot hole in and end up with a bit 1mm smaller then the grub screw thread so 5mm bit for m6 screw, 7mm bit for a m8 screw etc. You should be able to tap the remaining parts out if it doesn't come out as your drilling with the heat and movement.

    I would try an over sized torx bit hammered in with heat as others have mentioned, but most of the time drilling it out is easier and quicker then messing about trying to extract.
    Tom, Sundance
    2wheels1keel.com

  3. #13
    Join Date
    Aug 2011
    Location
    Poole
    Posts
    393

    Default Re: Drilling out a bolt

    Quote Originally Posted by lw395 View Post
    A left-handed drill bit will often grab in an allen head and unscrew it.
    This ^^^^

    LH drill bits are amazing, but difficult to get hold of in metric sizes.

  4. #14
    Join Date
    Jul 2005
    Posts
    6,876

    Default Re: Drilling out a bolt

    Quote Originally Posted by Yellow Ballad View Post
    New cobalt drill bit, slow and lots of lube, it'll go through it like butter. Being an allen key should be enough to guide it, get a pilot hole in and end up with a bit 1mm smaller then the grub screw thread so 5mm bit for m6 screw, 7mm bit for a m8 screw etc. You should be able to tap the remaining parts out if it doesn't come out as your drilling with the heat and movement.

    I would try an over sized torx bit hammered in with heat as others have mentioned, but most of the time drilling it out is easier and quicker then messing about trying to extract.
    +1

    and I would use a spotting drill for maximum rigidity. Very slow, steady pressure and thin oil.

    https://m.ebay.ie/itm/KLOT-Solid-Car...d=511495230251

  5. #15
    Join Date
    Jun 2015
    Posts
    28

    Default Re: Drilling out a bolt

    Thanks to all.very helpfull .
    Determined to have patience this time. Ordered mini butane torch and off to get the right drills.

  6. #16
    Join Date
    May 2007
    Posts
    31,255

    Default Re: Drilling out a bolt

    Quote Originally Posted by bignick View Post
    This ^^^^

    LH drill bits are amazing, but difficult to get hold of in metric sizes.
    One place I worked, we labelled LH drills as 'PZ2, PZ1 and PZ0'.
    We used them to remove small countersunk machine screws which had been loctited in place as a tamper-evident fixing.

    You sometimes see 'screw removers', which are a bit like a LH drill without the flutes, i.e. just the tip ground.

    Another thing which works on loctited screws of various varieties is a suitable 1/4 hex bit heated with a blow torch or kitchen gas ring. Mind how you go, the magnetic bitholder will stop working above the curie temperature.... Use a bit holder with a spring clip in it.

  7. #17
    Join Date
    May 2010
    Location
    S. Dorset
    Posts
    353

    Default Re: Drilling out a bolt

    If we are talking about those blasted hex nuts on the top of the rope cage, I gave up in the end and got an engineer to get that stubborn one out.

    He heated the area up and the nut moved.

    Apparently I had used the wrong type of LockTite, the type that sets like concrete !

  8. #18
    Join Date
    Dec 2005
    Location
    Far S. Cornwall
    Posts
    11,936

    Default Re: Drilling out a bolt

    I think an easy out without drilling first, to leave as much meat as possible to avoid it spreading. You can always drill after if no go.

  9. #19
    Join Date
    Jul 2005
    Posts
    6,876

    Default Re: Drilling out a bolt

    Quote Originally Posted by fisherman View Post
    I think an easy out without drilling first, to leave as much meat as possible to avoid it spreading. You can always drill after if no go.
    The problem with that might be that the easy-out doesn't have sufficient depth of engagement to grip well. An easy-out of that diameter won't be very strong . If, as the OP says, the screw takes a 2.5mm hex key he could drill that size and the easy-out would go further in. The hexagonal hole would guide the drill; if it is not badly mauled.

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