Hello all, I do not solder nichrome to the leadwires and have never needed to
do so (YMMV).
One conductor of the leadwire is snipped about 3/4 inch shorter than the other,
and about 1/4 inch of each conductor is stripped. About ten turns of nichrome
(32-36 ga) is wound tightly around both the copper of the shorter conductor and
the insulation of the longer one. The nichrome is spiraled up, about 2-4 turns,
around the insulation of the longer leadwire. Ten turns tightly around the
copper of the longer conductor, snip the nichrome. Dip.
The un-soldered connections will no doubt eventually corrode. How long does
that take? I don't know but I've used motor starters made this way that were at
least three years old with no issues. In practice it would probably be wise to
make no more than will be used within a year.
Some workers cut a bunch of pieces of nichrome of the length needed before
beginning. I've found those to be rather easy to drop on the floor, where I
usually can't find them. I prefer to start with a 2-3 foot long piece of
nichrome, snipping with scissors after winding each one.
Duplex "shooting wire" is most commonly used for leadwire, but the twisted
pairs in CAT 5 cable work nicely, and CAT5 is readily available at Home Despot
or other big-box stores. It's rather stiffer than shooting wire, which is good;
less likely to bend as nichrome is wound around it or as it's being inserted in
a long motor.
Best -- Terry "prfesser" McCreary
**These are "motor starters" or "initiators", not igniters (or ignitors,
ignitirs, whatever spelling you like 🙂). Igniters are BATFE regulated items,
while motor starters are not listed in the Orange Book (for now at least). 🙂
Nichrome isn't readily soldered, though Rubyfluid Soldering Paste with
60/40 rosin core solder permits rapid solid connections with the
nearly-invisible 36-g wire. I've found that a bridgewire of about
0.5-inch L will swiftly heat to orange-red with the Duracell, yet not
melt or burn thru. If that bridgewire is wrapped around the PVC
insulation of one bell wire strand, it becomes less fragile yet
well-exposed for pyrogen dip.