I have a hinged bangle which has a spring at the hinged joint.
The spring has broken and I am trying to replace it. I ordered an R
Hood
Hi R; Tempering a spring, especially a small one, is a tricky
proposition. I’d call a few music stores and see if they have any
"piano wire" of the right gauge. Sometimes, you can use piano wire
and simply bend it around without having to temper it. Spring steel
is a high-carbon steel. And spring steel wire is not easy to come
by. I’m afraid I don’t know a source, but a gunsmith might know.
The process of tempering involves the following steps:
1. annealing.
2. shaping.
3. hardening.
4. tempering.
Don’t heat the spring directly with the torch. Put it on a piece of
metal, copper or steel or other, and heat the metal from beneath.
Heat it till the spring is a red heat, then allow it to cool slowly
as follows: When it’s red hot, leave it on the metal and let metal,
spring and all cool slowly. This anneals the spring. After it
cools, shape the spring. Then, heat the spring, again using the
piece of metal, to a red heat and drop it in a small container of
oil. At this point, the spring is too hard. Don’t try bending it
now or you’ll break it. You will now anneal it back to the proper
temper as follows: Clean off all the discoloration till it’s bright,
clean metal, either by sanding, sand-blasting, or otherwise abrading.
Doesn’t have to be perfect, just clean enough to see the oxide
colors that will form when you heat it again to temper it. Put the
clean spring on the piece of metal, heat from the bottom, and when
the spring turns peacock blue, immediately drop it in a container of
oil. Gently test it by seeing if it bends. If it feels too stiff,
don’t force it or you’ll break it If this makes the spring too
stiff, you’ll have to temper it using oil that is kept hot. If the
spring is too soft, meaning that it doesn’t return to it’s shape,
you’ll have to adjust it back in shape and go through the process of
hardening it and tempering it again, but this time, don’t let it get
all the way to the peacock blue in the final heating, but rather stop
it at a straw-yellow color (yellow turning into brown). There are
many variations on this tempering method, and a little research might
turn up one that is a little more understandable than mine. It’s the
same process used to temper any steel tool, except that the tempering
colors are going to need to be appropriate for the high-carbon spring
steel.
David L. Huffman
