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Stripping 40 AWG/45 SWG or finer magnet wire/enamelled copper wire?

Discussion in 'Electronic Repair' started by N_Cook, May 9, 2008.

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  1. N_Cook

    N_Cook Guest

    To then be able to solder to coarser wire.
    Assuming coating will not melt off/evaporate at soldering iron temperature
    I tend to grip between 2 fingertips and abraid with the finest grade of wet
    and dry paper against a fingertip and turning wire around and repeating a
    few times. Would abraiding against a block of rubber be better or some other
    process altogether ? for minimised chance of localised (so failure point)
    weakness due to stretching near the stripping point. Perhaps a small
    fine-grade grind stone in a Dremmel with direction of rotation towards the
    bulk of wire, turning the wire .
     
  2. Jim Adney

    Jim Adney Guest

    Here's what's always worked for me:

    Hold the end of the wire in a lighter or match flame until the varnish
    just flashes off. You may need to move the flame around a little to
    char the whole length that you want "stripped."

    Take a postage stamp sized bit of fine sandpaper, 600 grit or finer,
    and fold it over once so that the sanding surface faces itself. Draw
    the wire thru the folded sandpaper, squeezed gently between thumb and
    forefinger, several times, turning it slightly between times until the
    wire is cleaned down to clean copper.

    It's actually quite quick and easy.

    -
     
  3. N_Cook

    N_Cook Guest

    But the breaking strain of such fine wire is only a few ounces and wouldn't
    such heating weaken such wire. My bottle of MEK is now nearly full of empty
    space and no idea where to get anymore.
     
  4. James Sweet

    James Sweet Guest


    Most hardware stores carry it by the quart and gallon here in the US, no
    idea about UK.
     
  5. Ross Herbert

    Ross Herbert Guest

    :To then be able to solder to coarser wire.
    :Assuming coating will not melt off/evaporate at soldering iron temperature
    :I tend to grip between 2 fingertips and abraid with the finest grade of wet
    :and dry paper against a fingertip and turning wire around and repeating a
    :few times. Would abraiding against a block of rubber be better or some other
    :process altogether ? for minimised chance of localised (so failure point)
    :weakness due to stretching near the stripping point. Perhaps a small
    :fine-grade grind stone in a Dremmel with direction of rotation towards the
    :bulk of wire, turning the wire .


    Forget the burning or scraping options, and there is no need to go out trying to
    find a source of xylene. Use a rapid paint stripper - it works excellently.
    Leave it for a minute and then wipe off with a tissue.
     
  6. N_Cook

    N_Cook Guest

    I tried some ordinary "slow" paint stripper , gloopy stuff. Scooped into one
    of those 2cc polythene bottles that expensive military connectors come in.
    Has a flap lid so can seal and reuse. That takes some time to soften.
    Contained dichloromethane and methanol.
    What to look for in contents of rapid versions or trade-name?
     
  7. Smitty Two

    Smitty Two Guest

    Just curious, but if you're winding your own coils, why not use the
    thermal strip variety of magnet wire? Mechanically stripping the fine
    stuff is a pain.
     
  8. N_Cook

    N_Cook Guest

    Because I have a few hundred (maybe thousands ) miles of laquered fine
    copper wire.
     
  9. Smitty Two

    Smitty Two Guest

    42 "single poly" is about 10 miles to the pound. So you have 100 pounds
    or so? If you're going to use that much, that's a lot of terminating
    you're going to struggle with. If you just need a bit and you're
    packratting the rest, you could sell it on ebay and pick up one or two
    five pound spools of the thermal strip.
     
  10. Jim Adney

    Jim Adney Guest

    Heating certainly anneals the wire, but if you draw the wire GENTLY
    thru the sandpaper it will be fine. You may need to do this a few
    times to get the hang of it without breaking the wire, but I've
    actually never had a problem with it.

    -
     
  11. N_Cook

    N_Cook Guest

    I've always been wary of chemical because of the possibility of not being
    able to guarantee the complete nulification of corrosive chemical and
    unknown long term effect on solder and any heating must weaken the wire.

    I agree with you, that if one can make sure that the forces used with very
    fine emery cloth is less than the backforce drag inherent in the winding
    process then I think that is the most reliable route.
     
  12. N_Cook

    N_Cook Guest


    So what is the best mechanical technique?

    For this finest wire I've only used a single-sided action of fine emery
    against a finger.
    As an experiment, later today, I will fold some fine emery, stick a piece of
    paper either side of a clear space on one flap of the emery, to reduce the
    grabbing effect of double-sided action with no spacers. Tie the 40/45 wire
    to a spring guage and try double-sided stripping of the wire and see what
    the axial forces are, to get down to clear copper.
     
  13. N_Cook

    N_Cook Guest

    I think I'll stay with abraided stripping.

    Making a paper spaced emery stripper gives lot better control.

    So results for 40AWG/45SWG wire tested at a breaking force of 4 oz with knot
    and 5 oz with rubber clamping.
    Perfectly good double sided stripping at no more than 2 oz of force.
    Interspercing with a sheet of paper in the jig, so single sided , only 1 oz.

    So even double action and repeating a few times, to strip around, then
    should comfortably remain within the elastic limit. Or putting it another
    way much the same as the back-torque for tidy winding of that gauge of wire.

    The slight abraiding of the copper can only help for tinning/soldering as
    compared to any remnant chemical or burning residue.
     
  14. Ross Herbert

    Ross Herbert Guest

    ::>
    :> :To then be able to solder to coarser wire.
    :> :Assuming coating will not melt off/evaporate at soldering iron
    :temperature
    :> :I tend to grip between 2 fingertips and abraid with the finest grade of
    :wet
    :> :and dry paper against a fingertip and turning wire around and repeating a
    :> :few times. Would abraiding against a block of rubber be better or some
    :eek:ther
    :> :process altogether ? for minimised chance of localised (so failure point)
    :> :weakness due to stretching near the stripping point. Perhaps a small
    :> :fine-grade grind stone in a Dremmel with direction of rotation towards
    :the
    :> :bulk of wire, turning the wire .
    :>
    :>
    :> Forget the burning or scraping options, and there is no need to go out
    :trying to
    :> find a source of xylene. Use a rapid paint stripper - it works
    :excellently.
    :> Leave it for a minute and then wipe off with a tissue.
    :
    :I tried some ordinary "slow" paint stripper , gloopy stuff. Scooped into one
    :eek:f those 2cc polythene bottles that expensive military connectors come in.
    :Has a flap lid so can seal and reuse. That takes some time to soften.
    :Contained dichloromethane and methanol.
    :What to look for in contents of rapid versions or trade-name?

    The slow stuff is no good...

    Here's an MSDS for a brand I know works
    http://msds.orica.com/pdf/shess-en-cds-010-000703515901.pdf

    The active ingredient is Methylene Chloride so an alternative with that chemical
    in a similar proportion will do the job.
     
  15. Ian Jackson

    Ian Jackson Guest

    Of course, if the wire is actually polyurethane-covered (not enamel),
    you don't even bother to remove it. It comes off when you tin the ends
    (prior to the actual soldering). Even if it is enamel-covered, you may
    still be able to remove it by trying to tin it using a very hot
    soldering iron (eg Weller #8 bit) - or, at least, after trying to tin
    the wire (and apparently failing), the enamel may be crumbly. If so, you
    can usually scrape it off with your finger nails.
     
  16. N_Cook

    N_Cook Guest

    And how fares Cu metallurgy at/after 800 degree F ?
     
  17. Jim Adney

    Jim Adney Guest

    I've never tried the one-sided approach, but it's worth testing. Just
    don't forget to char the enamel first, because I think that's the key
    to making it come off easily.

    I suspect that even those who are used to chemical stripping will find
    this method to be faster and less hassle. There is some risk of fire,
    but less than lighting a cigarette, and I prefer to keep the nasty
    stripping chemicals out of my lungs.

    -
     
  18. Jim Adney

    Jim Adney Guest

    That works just fine with some coatings, but not at all with others.
    It's worth trying first, however.

    -
     
  19. Jim Adney

    Jim Adney Guest

    It's probably annealed by then, but that's all. It's melting point is
    above 2000 F, so you're a long way from that.

    Once it cools back down to room temp the only change in the copper is
    that it will be annealed.

    -
     
  20. Smitty Two

    Smitty Two Guest


    It'll be fine. That's a pretty common soldering temp, and used for
    thermal strip coil wire. We never pre-tin it, just terminate and solder.
     
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