mike wrote in message
news:h4Fpj.6842$M71.5985@trnddc08...
N Cook wrote:
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 ?




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
problem?
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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.


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Diverse Devices, Southampton, England
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