"Gunner" wrote in message
...
A young entrepreneur friend of mine makes spear guns, spears, etc.
He
has been getting his spears heat treated at a commercial treater,
but
the costs are eating him up.

Here is the requirements... a stack of 6 foot long spear blanks has
to
be kept at 925F for 2 hours. They are about .30 in diameter.

Pretty simple.

Now the problem...making an oven 6+ feet long that will reach that
temp fairly uniformly over the entire length.

Propane is probably the cheapest way, or even city gas.


We were thinking of a 7' length of 6" Sched 40, slid into a 7'
lenght
of 12" Sched 40, using either ribs welded to the outside of the 6"
pipe to keep it centered, or something similar.

Now the big issue...how to make a burner(s) that will uniformly heat
the inner pipe.

I recall seeing a set up many years ago, that somehow managed to get
a
spiral of flame down the inside of the outer pipe that actually
wrapped around the inner pipe. It was fascinating to see. But we
would be happy to get any sort of unifiorm flame...G

Anyone with any hints, links ideas on how to accomplish this task?

I do have a 350' roll of .065 x .125 nickle flat resistance
ribbon..but think it would be a bitch to make this thing run on
electricity, and expensive to operate.

Help!

Gunner, actually starting a thread on-topic G

Lathe Dementia. Recognized as one of the major sub-strains of the
all-consuming virus, Packratitis. Usual symptoms easily recognized
and normally is contracted for life. Can be very contagious.
michael


Gunner,

Find a temperature controlled pottery kiln. Certainly over here in the
UK the bigger they are, the cheaper they are second hand. I bought a
medium sized one a few years back to use for lost wax burn out, but
actually have used it more for heat treatment.

AWEM