On Wed, 31 Aug 2005 18:29:30 +1000, Jordan wrote:


I'm thinking I can use heat to soften the spring for bending and
drilling, then reheat/plunge in liquid to get the springiness back -
correct?

Yes, you can anneal spring steel (other than HSS or other exotic alloys)
by heating red hot and then slowly cooling.

To harden the spring requires two steps. First bring to red hot and then
plunge in water. This should make the spring very hard and brittle.
The second step is the actual "tempering" step. Clean the spring to
bright metal condition. Then reheat it until the steel turns "straw" yellow
(about 460 deg. F.) and allow it to cool. This step removes some
of the hardness and brittleness.

Actually, different applications use different levels of temper, and I
can't find drawing temps for springs in my Machinery's Handbook right now,
so I may be misremembering the proper color above (might be blue?).

The color that the steel turns during tempering is an indication of how
hot it is getting, and subsequently how much softer the steel will be
from its completely hard state (from step one).

Is hacksaw blade really usable as spring? HSS? Carbon steel?

I don't know, but I suspect that a carbon steel hacksaw or bandsaw
blade is hardenable. The only other blades I'm familiar with are
"bi-metal" which I think is a term used to mean that only the teeth
of the blade are hard, and the rest of the blade is just mild steel.
I'm not sure though. If so, then you'd have to add carbon to the steel
to make it hardenable.