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

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 .

 

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.

-

 

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.

 

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

 

: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
rocess 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
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?

 

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.

 

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

 

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.

 

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.

-

 

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.

 

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.

 

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.

 

::>
:> :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
ther
:> rocess 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
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.

 

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.

 

And how fares Cu metallurgy at/after 800 degree F ?

 

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.

-

 

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

-

 

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.

-

 

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.