On 2013-08-05, BQ340 wrote:
I need to duplicate an old flat spring but need to match the hardness or
flex. The "spring" is just a small flat piece, 3/16" wide, 1-1/2" long
and .005" thick.
[ ... ]
All I know is it really hard (brittle) -it will snap if you try to bend
it in half.
[ ... ]
Does anyone know if blue spring shim stock will bend or break? If it
bends can I temper it more to get the hardness (flex) that I need?
Blue spring stock (not shim stock, which I have not tried, but
the coils of spring stock) will bend as long as you don't want too small
a bend radius.
Tempering it would make it softer. You would need to harden it
(and how hard you can get it is a function of the alloy). And to treat
something like that (you have to get it up to at least red hot) you
would be exposing it to serious oxidation -- unless you have an oven
which you can pump argon into before getting it hot. Then it has to
come out quickly and go into the quench before it cools any. (Probably
better to have a stack of them together, so the center ones at least
would not cool too much before the quench.) And if you want it that
hard, quench in brine (very strong solution of salt in water), which
will probably get it as hard as you can manage for whatever alloy you
have. (This would work with your clock spring as well.)
If you heat it in air, the oxygen will burn out the carbon in
the alloy.
To find your target hardness, you will want to do a Rockwell
hardness measurement -- with the "superficial" scale, because the spring
is not thick enough to be done with the Rockwell C scale -- that needs
more depth under the surface.
Once you know the hardness of the originals, you can then try
the heat and quench with new spring stock and see what that does
straight out of the quench. If it is too hard, then you get into
tempering (heat to a given temperature for a given time to reduce the
hardness a known amount.
Good Luck,
DoN.
--
Remove oil spill source from e-mail
Email: | (KV4PH) Voice (all times): (703) 938-4564
(too) near Washington D.C. |
http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---