Bill said:

> I haven't purchased one yet but they are not expensive and look like they
would be easy to
> adapt to a made-up holding fixture.  More horse power, right?


Yes and no. If you have a space outdoors, and can shroud a space with firebrick
or refractory, or, for that matter, a clean steel drum, sure. They don't
throttle down very well, and suck fuel fast. For a small item, it can be
difficult to keep from overheating.

My favourite for things too big for my good heat treat furnace (it is an
upgraded dental furnace with a box about 60X60X50mm.... If I  had the money, I
would go 200X200X200mm with a good controller, but I don't have the space for
larger, though larger is cheaper as a second hand ceramics kiln) get done on the
grill. A fire pit will do as well. Charcoal gives a nice reducing atmosphere and
will achieve temperature for hardening steel in a fairly uniform and controlled
manner.

When charcoal isn't practical, the midsize plumbers torch or acetylene-air
turbotorch get used, but they take a lot more care.


> I have plenty of used motor oil, so I guess I'll give that a try. The new pot
was pretty expensive, but LOML likes it!

It'll be fine. As said by others, use a container that you can cover to smother
flame. I use an old steamer pot. The basket makes it easy to get parts out, and
the lid goes on immediately after the part goes in.


> At least one knowledgeable galoot suggested torch tempering. I think I'll go
with oven tempering at 350 - 400 degrees for 45 minutes to an hour.


For point tools, I use the traditional "quench the tip, and quench again when
heat runs back to the tip and the color at the tip is right" when I can, and I
go with the toaster oven or big oven in the kitchen for larger. I watch the
color if I can, and usually drop a thermocouple in (make sure it's near the
part. Just close the door on the lead gently) to monitor temperature. Slow
increase makes for uniform tempering temp. For the inexperienced, I would
suggest the slow job in the oven. Just be sure to preheat to reduce overshoot,
and check the thermostat, as consumer ovens are notoriously inaccurate. Start a
bit low, look at the color, and raise the temp if needed. The traditional method
has the advantage that the material behind the tip is just shy of annealed with
little risk of cracking or chipping.


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