On Fri, 14 Oct 2011 16:00:54 -0700, TrailRat wrote:

OK, now I know what I'm looking for I have a question about strength.

I am in the process of making a pair of manacles for a friend for a
halloween costume. The manacles are meant to look steampunk and are of a
steamed curved hardwood with brass fittings. The hinge will be brass and
I plan on replacing the hinge pin with a d-ring. This is for a small
length of brass chain (3-4 links). Despite these being a costume piece,
I am more then sure that they will see use and I am more then sure that
some bright spark will try to "break free" by tugging on the links. You
know how that goes, I'm sure you've seen that in the movies! Anyway, to
save face I have decided to spot weld shut the gap in the d-links so it
doesn't separate under tension.

Will that work?

I don't quite see how the D-ring will replace a pin, and don't see
the wisdom of making the manacles strong, but all that aside, is the
D-ring brass, or is it steel? And is the D-ring junction in the
middle of the flat side of the ring?

For a ring, brazing might work better, for either steel or brass,
because most little spot welders can only weld together bits of
metal sandwiched between the electrodes, with current from electrodes
flowing through the sandwich. Most heating occurs at the junction
between the two sheets, because that junction typically has much
higher resistance than other points in the circuit.

If you try to spot weld a D across the junction (perpendicular to the
plane of the D) with nothing pushing the ends together, it won't work
particularly well. It might make a connection stronger than most people
can pull apart, but probably wouldn't resist being bent apart by hand
(if someone can bend the ring). There are commercial welders for
D-rings, that push the ends together and run the current axially
through the junction, in the plane of the D, making a connection as
strong or stronger than the wire of the ring.

--
jiw