On Feb 1, 3:06*am, des bromilow wrote:
G'Day,

We've got a piece of 1/4" spring steel rod (as hard as piano wire) - typical
grade spring steel (1080) which we need to make a tightly wound shape with.

The local spring guy told us to form the tight curves (around a 3/8" bolt)
by annealing the wire to dull red and winding around the form, but obviously
this then leaves the rod in an annealed state.

How to we then harden and temper the rod back to a spring?

The shape is best visualised as the metal frame of a slingshot (it's actually
part of a motorcycle seat) so it won't make full contact on a flat surface.

If someone with some experience in this type of work can tell us the proper
way to harden and temper this we'd appreciate it. We have oxy-acetylene,
and propane torches available, and our previous experience with this spring
steel grade has been to quench in oil.
If you can tell us the colours to heat to, or temperatures it'd be great
- similarly if you have any tempering methods to acomodate the irregualr
shape (is a domestic overn OK to use?)

Thanks,
Des

remove the german anti-spam device off my email address to reply

The classic method for repeatable spring tempering is heating in a
lead bath. For higher temperatures, there are salt baths. Obviously,
the bath has to be large enough to handle the part, if it's too big,
I'd suggest hunting up a heat treat outfit with a suitable furnace.
You can get thermometers made for lead baths, salt baths run hot
enough to require a pyrometer.

If you're stuck with torches and it's a small part, make up an
enclosure with fire bricks first, then heat up beyond the non-magnetic
point and quench in oil. Temper in the lead bath afterwards.

This assumes that your wound kinks aren't done too tightly and there's
no nicks or abrasions in the surface. Otherwise your rider is likely
to get the point when it breaks! It's going to take some testing
before you can strap in onto the bike.

If it's true music wire, you might end up with a brittle mess. Music
wire depends on the drawing process for a lot of its spring.
Annealing will remove that stress, leaving you with a not so-springy
result. Hardening and tempering afterwards is kind of iffy, in my
experience. It usually breaks at a bend.

Stan