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how to remove striped allen screw?

Discussion in 'Electronic Repair' started by dansawyeror, Apr 20, 2007.

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  1. dansawyeror

    dansawyeror Guest


    The gear has a dial with a small, striped allen screw. The tool is 1.5
    mm. Any thoughts on how to get this off?

    Thanks - Dan
  2. Can you drill it out? That's usually how I deal with stripped screws.
  3. Meat Plow

    Meat Plow Guest

    Drill with a CCW bit.

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  4. ISTR that Sears sells a small extractor set.
  5. N Cook

    N Cook Guest

    CCW/ left hand drill bit in a CCW/left-hand drill preferably, they both do
    exist but the bits are a bit hen's teeth. The last time I enquired at the
    main local engineering supplier (been there 50 years) the bod behind the
    counter looked at me as though I was trying to wind him up (CCWise of
    course). For such small diameter extraction it is just a matter of
    regrinding a standard drill bit with the opposite throw on the cutting end.
    Swarf clearance is irrelevant for this. Remember to mark the storage box
    with big letters that the enclosed bit/s is/are CCW. Where I used to work it
    a the fun thing for the mechanical engineer to supply the electronic
    technicians with one of his CCW bits to see how they reacted , ie coming
    back complaining that he'd supplied a blunt bit.
  6. DaveC

    DaveC Guest

    The gear has a dial with a small, strip[p]ed allen screw. The tool is 1.5
    I presume that the screw head is flat (counter-sunk) or you wouldn't be
    having a problem grabbing the head with vice-grips and just twisting it out.

    Get a real small cold chisel and a ball-peen hammer. Use the corner of the
    chisel to cut a divot into the face of the screw near the edge of the screw
    head. Then, tapping the chisel's corner into the divot, turning it CCW,
    "walk" it out.


    If the head is not flush with the surface around it, use the chisel to cut a
    "bite" into the edge of the screw head. Then, tapping the chisel into the
    bite, turning it CCW, "walk" it out.


    Drill in the hex hole with a drill bit larger than the diameter of the screw
    shank. When the head pops off, remove the dial and grab the remaining screw
    shank with a pair of vice-grips and unscrew.


    Weld another bolt onto the head of the stripped out screw head. Unscrew both.
  7. Oh, come on, why complexify your life? Just use a normal drill. What
    difference does it make ifyou tighten the screw more as all of it wil be
    removed. Once the screw has been drilled out, retap with the next size
    and install a new screw. Done. :)

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  8. PeterD

    PeterD Guest

    The trick is that the left handed bit often causes the screw to come
    out before drilling through it. Major help especially for hardened
    screws, and when you drill through the screw fully, you also dimple
    the shaft making it more difficult to align the newly installed knob
    or gear sometimes.
  9. N Cook

    N Cook Guest

    Exactly my experience that often the biting torque of a slow speed LH drill
    and LH bit is all that is required to undo it. I've kept an otherwise unused
    big yellow low rev , mains powered, but reversible drill for this purpose
    and a set of bits , mainly myself LH cutting-face counter-ground, right hand
    bits from 1.5mm to 6mm. Another tip is to have a few more with a long piece
    of matching diameter rod brazed/welded to these LH bits for drilling
    out/removing grub screws in knobs at the centre of large bits of kit.
    You know the situation, corroded steel in aluminium or brass knobs or
    inserts of knobs or steel in steel shafts etc
  10. Guest

  11. Guest

    If it's not countersunk, a small pair of vice-grips does nicely. I
    have even had success using small haemostats. If it is counter-sunk,
    there are any number of extractor-bits available for your drill.

    Peter Wieck
    Wyncote, PA
  12. Go to Sears and look at the sets of screw extractors (Easi-Outs),
    perhaps one the right size will grip the inside of the allen screw. You
    might have to drill out the center however.

    Joe Leikhim K4SAT
    "The RFI-EMI-GUY"©

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    For if it prosper, none dare call it treason."

    "Follow The Money" ;-P
  13. If it's not countersunk, there are obviously far more options.

    When taking things apart to salvage some parts, I've used a cutoff
    wheel in a "Dremel" tool to put a slot in bolts that have unusual
    heads (usually there to prevent tampering). Slice a slot across
    the top, then use a regular screwdriver to remove the screw.

    Of course, it doesn't work if the bolt/screw is embedded.

  14. Guest

    funny that one of the worst methods is so popular. They have a habit
    of making the screw unremovable.

  15. N Cook

    N Cook Guest

    I think I have 2 sets of "easi outs" the smallest ones broken in each set
    and even then not small enough for the usual "electronic" seized screws.
    Incidently they are CCW / LH (lazy) threaded also.
    Incidently using left hand drill bits for grub screws set in bakelite knobs
    its a matter of making some small guide tubes to sit in the bakelite and
    guide the LH bits into the centre of the screw so it doesn't slide off the
  16. sit in the bakelite

    "Sit"? You mean drill and insert into the bakelite? The cure sounds more
    drastic than the ailment...
  17. I have a suspicion that Easi-Outs get misused. I suspect they're
    intended for new bolts that have been overtightened and snapped off, not
    old ones that are corroded in place. Everyone I know who tries to use
    them to remove seized bolts ends up with a bolt with a snapped-off
    Easi-Out in it, and the stupid things seem to be harder than any known
    drill bit. ;)

    Besides, the original post was about a 1.5mm set screw. That's awfully
    small. It's hard for me to see any method other than drilling being
  18. N Cook

    N Cook Guest

    Using a LH drill bit , you have to choose the drill size carefully. I don't
    know if its the bite or the localised vibration or even isolated heating but
    the LH action I would say 4 out of 5 times threatening the screw with such a
    drill makes it undo ( if its just airborne corrosion that has seized it)
  19. Grind it out or spark it out. Neither will be fun or cheap.
  20. Guest

    What do you mean by spark it out?

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