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

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On Mon, 01 Feb 2010 10:06:40 +0000, 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?)

I don't see how you're going to get it up to uniform temperature for
quenching without some sort of furnace. You may be able to get away with
something primitive built up from a pile of firebricks, but I think
you'll need something to contain the heat. Just torches probably won't
give you even enough heat.

--
www.wescottdesign.com

You need to heat it to about 1500F to 1600F, oil quench, temper at 900F
to 1100F depending on exactly where you are trying to get to. Neither
one of those temp ranges is easy to get to with just a torch or a
kitchen oven.

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

On Feb 1, 11:55*am, RoyJ wrote:
...
des bromilow wrote:
....
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.

So what happens when this spring breaks?

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

Ed Huntress wrote:

All in all, it sounds like it's worth having it done by a specialist.

Or time to redesign the part to use an off-the-shelf spring.

On Feb 2, 1:58*am, spaco wrote:
Here's one more opinion:

Why not take it to the local spring guy after you have shaped it?



We'd love to have the spring guy deal with it - he's the pro and quite
good at it, but he's on the way to closing down. - typical story -
urban encroachment surrounding his workshop, new houses full of
whinging greenies who complain about the smell and noise of the
machinery/forges - and with the various govt "suggestions" about
taking the older vehicles (mostly trucks) off the road, the newer ones
having air springs, he's pretty much out of work, and out of the
nieghbourhood.
He's lucky to work 8 hours per week spread over two or three days so
it's pretty much a given we can't use him for much longer.

The piece is to replace a seat part in a veteran motorcycle, so
appearance and function is what we're aiming for. We'll go with the
firebrick forge/hearth and try and make it work.

Thanks All,
Des