Home made heat treat oven information

That'd give you a carburizing atmosphere, perhaps useful for case hardening, but more likely to produce a large BOOM if any air remains in the furnace.

Not much use for an oxidizing atmosphere in a heat treating furnace. You'd get *lots* of scale, decarburization of the steel, etc.

Now you're talking. An inert atmosphere will prevent either carburization or oxidation of the steel. The part will come out nice and bright and clean with exactly the chemical composition it had when it went in, but with a different grain structure due to the heat treating. That's exactly what you want.

Gary

Reply to
Gary Coffman
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Yup. Could just as well run opposite walls in parallel, or any other kooky combination you feel like conjuring up. Just didn't occur to me in my tired state ;)

Tim

-- "That's for the courts to decide." - Homer Simpson Website @

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Reply to
Tim Williams

Must be because of the cyanides...

BTW... what kind of temps and soak times are required to get how much case thickness? I tried case-hardening a bit of keystock (galv. mild CRS) the other week by cycles of heating it (the thin layer of galv. oxidized/burnt off) to orange and dipping in powdered oak charcoal for a few minutes. Also tried coating it with borax and dipping that in the carbon. (As sticky as borax is, it doesn't seem to do much with powders. Bah!)

Afterwards I quenched it and it seemed harder, maybe up to a 1030-1040 range I guess, Idunno... Spark test didn't show much, although I shouldn't be expecting it to, eh?

Tim

-- "That's for the courts to decide." - Homer Simpson Website @

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Reply to
Tim Williams

I have often considered the same thing, but have never read that is the case. There has to be a good reason the industry goes out of its way to carbonize (coke) peach pits.

No, you shouldn't expect much by that process because of the brief exposure of the metal to carbon monoxide. Pack hardening yields a depth of carbon of about .015" for the first hour, then drops off to roughly .010" per hour afterwards. By the time you have a thickness of roughly .090", the deposit tends to drop off to zero, although I'm sure there must be exceptions. Where I worked. they'd cook things for hours to get the depth desired The parts were placed in steel boxes with snug fitting lids, along with the peach pits, which were still very recognizable, but resembled typical coke otherwise. Temperatures for proper transformation run from 1,500F to

1,800F, depending on the material at hand.

Harold

Reply to
Harold & Susan Vordos

By the time you buy a controller, insulation, etc, what would that cost? I did a quick search on kilns and burnout ovens and found that you can buy a small, digitally controlled oven that heats up to about 2000 degrees F for around $500. They are a little smaller, maybe 6 to 8 inches cubed but a larger one can be had for about $200 more. I would imagine that the controller would be the most expensive part.

Dave

Reply to
dberryhill

Well considering he scavanged the firebrick, I'd say there goes a BIG part of the cost! ;-)

Tim

-- "That's for the courts to decide." - Homer Simpson Website @

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Reply to
Tim Williams

And wire from the scrap yard! They have tons of it, complete with stainless steel frames what hold the little ceramic insulators etc all set up and ready to go. Just bend it to form a hollow center and stack insulated fire bricks around it. :)

Not home dryer/furnace equiptment but industrial stuff. I got my share ;) but now what? How do I figure the wire vs. the electric requirements so that I can get as close to right as theory allows?

I know Ohm's law but what's got me messed up is the resistance of the wire changes as it heats up. :/ What happens with that? And the idea of containing the heat as opposed to blowing air by it.

My guess is all that stuff is setup for preheating air with an unknown voltage applied.

Working with unknown wire alloys, only wire length and diameter is known. Resistance can be known too, but where to start on that?

I'd like to set it up for 240v.

So what's got me messed up is the heat/temperature output from an unknown quanity of wire.

Any clues you can give me on that? Or resources that I should read?

(got the website address from earlier in this thread and will look into it later)

Alvin in AZ

Reply to
alvinj

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