Jack Schmidling wrote:
I need a piece of 1/4" hardened drill rod about 33" long but I have no great
ideas on how to heat treat such a long piece myself and can't seem to find a
source for pre-hardened rod.

Anybody know a source? It doesn't have to be ground or of any precision at
all, just a nominal 1/4".

It occurs to me that air-hardened material may be a possibility but I am not
clear on how this is done.

js



Don't know where to find pre-hardened shaft but if you end up having to
do it yourself, it's gonna be tricky hardening the whole thing without
warping.
I'd get oil-hardening steel (O1) and rig up a "furnace" with a pile of
firebricks and a coiled nichrome element set in a channel formed by the
firebricks. You need a temp control to regulate the element, an
electric rangetop burner control will work.
Heat the shaft red hot until it loses it's magnetism, and hold it at
that temp for 15 minutes--that's called "soaking" and makes sure the
heating reaches the inner core of the metal.
Use olive oil for quenching, although cheaper vegetable oils will
probably work OK.
The best way to avoid warping is to quench the shaft vertically so a
tubular container for the oil could be made from PVC drainpipe with a
cap glued on the bottom.
Do the quench quickly, grab an end with visegrips and drop it straight
down into the oil then agitate it up/down and around for a few seconds.
Then to draw the temper as another poster outlines, use the firebrick
furnace again with the heat turned down low after polishing the shaft
bright to see the oxidation colors.

Ken Grunke

--
take da "ma" offa dot com fer eemayl


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