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Stubborn 3mm screws

Discussion in 'Electronic Repair' started by N_Cook, Nov 27, 2008.

  1. N_Cook

    N_Cook Guest


    ah, decent tool supplier. I went to my otherwise respected decades
    residency, local engineering tool supplier , a couple of years back. A
    middle aged bloke on the counter, not teenager. I asked what range of small
    size left hand drill bits they had - he thought I was taking the piss, like
    asking for long stands, golden rivets etc.

    ( used in drills with reverse action for drilling out and often releasing,
    in the process, seized screws , broken studes etc )
     
  2. Eeyore

    Eeyore Guest

    Now I think of it, you're right. Those kits were GKN. But Pozi screws are now
    somewhat more universal than Phillips for all the design reasons stated. I
    can hardly remember when I last had to use a Phillips driver.

    Graham
     
  3. Eeyore

    Eeyore Guest

    Well... some of my Stanleys, in fact probably most of them are > 30 years old
    and in fine fettle.

    You needed to buy the Chrome Molydenum ones.

    Graham
     
  4. Eeyore

    Eeyore Guest

    I avoid that shit.

    Graham
     
  5. Eeyore

    Eeyore Guest

    They are toughened. You can see the surface treatment.

    Graham
     
  6. Baron

    Baron Guest

    I thought that HP used Torx head screws !! Though most European
    computers use Philips heads screws, not Posi !
     
  7. Baron

    Baron Guest

    Left hand drills were very commonly used in multi spindle drills ! All
    the spindles were driven by gears or a chain from a single motor.
    But you right they are quite hard to come by nowadays !
     
  8. Buggers the cutters though, and they're not cheap.
     
  9. Jamie

    Jamie Guest

    We call them Easy outs over here.


    http://webpages.charter.net/jamie_5"
     
  10. Jamie

    Jamie Guest

  11. N_Cook

    N_Cook Guest


    Not the same thing at all, other than having LH thread of sorts. That's what
    you use after drilling a hole, but what do you use for say <4mm studs/busted
    or seized screws ? - LH drill bits.

    Where I used to work there was a full set of LH bits in a case covered in
    hazard tape and warning messages.
     
  12. Jamie

    Jamie Guest

    We only use LH bits only in the hopes that maybe the remainder will
    spin out as we're drilling. Mostly for small holes where easy outs are
    not practical. Even with that, our machinist still don't have much
    better luck, than just simply drilling out the hole as close as possible
    with a RH bit and run a tap down through it.

    Most of the problems I hand over to the machinist have loctite broken
    screws heads..

    http://webpages.charter.net/jamie_5"
     
  13. N_Cook

    N_Cook Guest


    This is the situation I commonly find, small screws, written up as a tip for
    others

    To free seized equipment knobs
    For the situation where the knobs are seized onto the shaft by rusted
    grub screws,especially where the screw penetrates the shaft;
    after you have butchered the grub screw slot try this.
    And it is one of ten virtually irreplaceable knobs.
    Make up some guide tubes,small enough to just slide into the hole
    in the knob containing the grub screw,these tubes drilled on a lathe with
    a clearance bore to take a drill bit. This drill bit usually needs to be
    extended by brazing onto a longish rod (so the chuck of the
    drill misses the face of the equipment).
    Use some cutting oil and drill into the grub screw.
    Ideally use left hand drill bits and left-handed power drill
    rotation, such drill bits are available from specialist suppliers.
    To convert a right hand drill bit well enough for this use grind the
    cutting face back on the opposite rake angle, swarf clearance
    is not relevant here. Often the bite into the drill bit
    into the screw or the localised vibration or heating is enough to
    shift the screw.
    Now use a small "easi out"(maybe this is a UK trade name),but consist
    of a coarse left-handed cutting thread on a coarse taper.
    Wind into the hole in the grub screw and hopefully extract.
    I don't use easi-outs as the smallest ones for this
    purpose are very week and if it breaks you have
    a lump of high carbon steel just where you don't want it.
    Maybe appropriate for very large knobs only.
    If this fails repeat the first procedure with larger diameter drill bits
    and appropriate protection sleeves
    until nothing remains of the grub screw,retap a larger hole and use
    a larger grub screw for knob reuse.
     
  14. Ross Herbert

    Ross Herbert Guest

    :philips heads , but glued or varnished in and any more torque on the
    :screwdriver will strip the head. I've tried heating for a minute with
    :soldering iron, no change. Have now left a dollop of paint stripper over the
    :heads overnight. Before using a left hand drill or griding off , any other
    :ideas ? Converting the cut off shaft of a screw driver to somehow fit a
    :standard (large) impact driver ?


    If you aren't succesful at removing the screws, and you don't want to grind them
    off and then use a small ezi-out - getting that small hole centred is a pita -
    then you might try the Rolson damaged screw and bolt remover kit
    http://www.rolsontools.com/search.asp?page=1&id=376&tt=1&ct=1&searchCat=0&searchStock=28997

    Maplin currently have it on sale for UKP8.99. It claims to be good down to 3mm
    screws and might be useful for the future.
     
  15. I've been using a #1 Phillips driver for the case screws on my Icom and
    Kenwood Ham Radio equipment. It seems to work OK, as long as I use a
    driver that hasn't had its tip rounded.

    Does anyone know if these particular screws are actually PoziDrive?

    Fred
     
  16. Eeyore

    Eeyore Guest

    True.

    My best bet however is to try several 'heads' from my driver and see which 'locks
    in' best. It's often VERY obvious !

    Graham
     
  17. I tried Phillips 0 and 1, as well as Pozidrive 0 and 1, on some Kenwood
    and Icom case screws. On the Kenwood, all 4 bits felt about the same!
    On the Icom, the PZ1 felt much more secure.

    The Icom screw heads have a small dimple where the PZ "X" might be.
    Since they are somewhat small screws, I wonder if the dimple is an
    abbreviated symbol for Pozidrive?

    Fred
     
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