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Pulling fine wire through sleeving query

Discussion in 'Electronic Repair' started by N Cook, Feb 4, 2008.

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  1. N Cook

    N Cook Guest

    I need to pull some doubled up , 0.22mm (9 mil, SWG 34, AWG 32) Cu wire
    through small bore sleeving. Some 0.3mm nichrome heater element wire
    stretched out until straight, worked rigidly enough, with "peristaltic"
    movement as a mouse (does this term translate across the pond ?) . I was
    probably lucky that "soldering" the copper to the ni-chrome made a
    sufficient strength overlap join to pull 1 wire through but I doubt it would
    work pulling 2 through, soldered or glued, because of added thickness of
    overlap bulge, when I have to repeat the process for the double one.

    Can anyone think of a source for thin wall ferrule / coupler to solder or
    probably glue over a butt join between mouse and 2 Cu wires, of these sorts
    of dimensions.
    Butchered mini-din socket pins are a bit too big diameter, but anything like
    that ?
  2. Ron(UK)

    Ron(UK) Guest

    Try a fishing tackle shop, ask to look at trace crimps.

  3. mike

    mike Guest

    Is the sleeving at all flexible? Probably if you snaked it thru.
    Stick it inside a hose, seal the ends with hot-melt
    and suck a vacuum between the pipes to swell the inner one.
    Apply some
    power to heat up the wire...depends on what the sleeve is made of.
    Might be able to accomplish the same thing with air pressure to
    pre-stretch the sleeving. To do it while you're pulling would
    require some fixturing, peanut butter jar and some hose.

    Is there any reason you can't make one overlap with the nichrome
    and a second overlap of just two coppers further back?
    A drop of superglue along a quarter-inch of paralleled wire is probably
    stronger than the wire. But you gotta pull two on the tensile
    strength of one.
    Sometimes a hammer can fix a bulge. Lead and copper are pretty ductile.
    Mash the nichrome flat then flatten the copper, solder it together under
    pressure. Trim with a hammer. Solder paste works well when you need to
    limit the amount to less than the surface tension would ordinarily allow.
    Spot welder? Think about tweezers with insulated sides.
    Squeeze the wires together and hit the tweezers with a charged cap.
    Probably take several tries, but if you're not making a production line...

    Just curious...what's wrong with bigger sleeving or heat shrink?
    You don't say the bore or how far you're pulling it, but you might
    be putting
    a lot of stress on tiny wire with thin insulation. Reliability
  4. N Cook

    N Cook Guest

    Ta, the nearest to a solution so far. 0.8mm internal bore seems the
    smallest they go to. Grinding a lead-in chamfer on the leading edge , and
    feeding through a tiny funnel of talcum powder may just work.

    Now what to do with the other 49 little crimps. They seem to be brass with
    a coating of dull varnish to dull them down for fishing purposes.
  5. Mr. Land

    Mr. Land Guest

    Would "soaping" the wire help, or are you already doing that?
  6. N Cook

    N Cook Guest

    I doubt if one atmosphere of pressure would make any diffenence to sub 1mm
    bore sleeving.

    I hadn't thought of flattening at the join. I will try that if the fishing
    trace crimp doesn't work.
  7. N Cook

    N Cook Guest

    Would "soaping" the wire help, or are you already doing that?

    I tend to use talc for that purpose.
  8. Ron(UK)

    Ron(UK) Guest

    We use them in the theatre, they are by far the best way of joining or
    putting loops in fine fishing line.

  9. N Cook

    N Cook Guest

    For swinging/flying actors around the stage - Peter Pan fashion ?
  10. Mr. Land

    Mr. Land Guest

    I meant something like this:

    Apologies if you already realized this was what I was suggesting.
  11. N Cook

    N Cook Guest


    I meant something like this:

    Apologies if you already realized this was what I was suggesting.

    I suspect that is for high clearance pulls. I've previously found that
    constricted pulls should be done dry, eg silicone oil hinders , so I'm
    assuming this product would as well. Presumably due to distributed surface
    tension of a constricted long run.

    I assume that mouse is a recognised term both sides of the Atlantic for the
    stidd wire threaders for existing conduit runs.
    Is it a myth that it derives from tying a thread to a mouse tail , let it
    run through conduit etc, and then pull through cables etc tied to the
  12. N Cook

    N Cook Guest

    While at fishing shop , bought a spool of fine line. Just to try the
    following - anyone been there before, ie wasting my time.
    Connect a source of vacuum at one end of the sleeving core and introduce
    some fine nylon line at the other, set turning on a small motor .
  13. jakdedert

    jakdedert Guest

    Not a good idea to put *any* splices in those cables. Better to simply
    replace the whole lot if too short for some reason. I was helping rig a
    lighting truss to which someone had affixed a 3'x12' wood and plastic
    sign. The initial installation left the sign too high, so the
    decorators simply spliced in additional cable using ferrules and a
    swaging tool. I had six folks on the ground holding the free ends of
    blocks & falls (more commonly known as block and tackle), while my head
    rigger was above, securing each in turn.

    As he did each one, there was inevitably a small amount of slack let
    out...nothing serious, but each connection bumped down a little less
    than an inch when the slack was let off and secured.

    On the second point, when the 'bump' happened, one ferrule failed. That
    end of the sign came swinging down in an arc with an audible WHOOSH!
    right past everybody's face! To their credit, nobody let go of their
    respective ropes, but the free end of the sign missed one poor lady by
    less than a couple feet.

    Once it had swung past vertical, the other end let go as well, and the
    whole thing crashed at our feet and shattered. No injuries, but some
    wardrobe changes were in order once the truss was let back down.

    No splices, please....

  14. PaPaPeng

    PaPaPeng Guest

    A hypodermic needle from a pet supplies, vet or farm supplies shop.
    Don't try the pharmacists. They feak out at the thought of selling a
    needle to a junkie.
  15. N Cook

    N Cook Guest

    The sound recording from December 4th, 1958 of this is better, for an
    example of perfect comic timing, but text

    Gerard Hoffnung
    (from his Oxford Union speech)

    I've got this thing here that I must read to you.
    Now, this is a very tragic thing... I shouldn't, really, read it out.
    A striking lesson in keeping the upper lip stiff is given in a recent number
    of the weekly bulletin of 'The Federation of Civil Engineering Contractors'
    that prints the following letter from a bricklayer in Golders Green to the
    firm for whom he works.

    Respected sir,

    when I got to the top of the building, I found that the hurricane had
    knocked down some bricks off the top. So I rigged up a beam, with a pulley,
    at the top of the building and hoisted up a couple of barrels of bricks.
    When I had fixed the building, there was a lot of bricks left over.
    I hoisted the barrel back up again and secured the line at the bottom and
    then went up and filled the barrel with the extra bricks.
    Then, I went to the bottom and cast off the rope.
    Unfortunately, the barrel of bricks was heavier than I was and before I knew
    what was happening, the barrel started down, jerking me off the ground.
    I decided to hang on!
    Halfway up, I met the barrel coming down... and received a severe blow on
    the shoulder.
    I then continued to the top, banging my head against the beam and getting my
    fingers jammed in the pulley!
    When the barrel hit the ground, it burst it's bottom... allowing all the
    bricks to spill out.
    I was now heavier than the barrel and so started down again at high speed!
    Halfway down... I met the barrel coming up and received severe injury to my
    When I hit the ground... I landed on the bricks, getting several painful
    cuts from the sharp edges!
    At this point... I must have lost my presence of mind... because I let go of
    the line!
    The barrel then came down... giving me a very heavy blow and putting me in

    I respectfully request 'sick leave'.
  16. Ron(UK)

    Ron(UK) Guest

    Erm... no, that needs something a little stronger than fishing line!

  17. Ron(UK)

    Ron(UK) Guest

    Cable companies regularly use ferrets to pull a cord through trunking,
    I`ve seen it done.

  18. Ron(UK)

    Ron(UK) Guest

    Indeed. There are very strict and specific regulations for the flying
    of any structure in theatreland. Fishing line is only used for very
    lightweight materials such as scrims and holding back swags etc.
    Anything of any substance must be flown using steel rope and the proper
    fittings applied in a precise manner. Anything flown above 2 metres must
    have at least one secondary safety bond to something that isn't going to
    come down.

  19. jakdedert

    jakdedert Guest

    Inever knew where that one originated, but like most such, there's
    probably an element of truth involved. In my case, it was exactly as
    stated...with only details (loacation etc) left out.

  20. jakdedert

    jakdedert Guest

    Indeed...not always done, however in the case of signage. Our (my)
    liability in this case was not properly inspecting the work of another
    contractor...complicated by the fact that it was another 'trade'
    organization. In fact, we should have crossed that trade boundary and
    done the work ourselves (which we in fact did, after the fact...once
    they rebuilt the sign).

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