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Step 4: HEAT TREAT

I used 0-1 steel, this requires a trip to the kiln to heat treat it. My dad told me that the atmosphere in the kiln will more than likely create a lot of scale (crappy nasty surface stuff) the way he takes care of this is to wrap his knives in steel foil and seal it up nice and tight.

I’m not sure of the temperature needed, but dad taught me a little trick; when the knife gets nice and hot, stick a magnet to it, if it doesn’t stick your good to go. This happens because all the molecules in the knife have gone to a semi liquid state that allows them to drift out of alignment, something needed for magnetization. So after about 15 minutes in the kiln and checking it twice with the magnet we were ready to quench it.

To quench the knife you submerge it tip first into room temperature oil, vegetable oil in our case. This hardens the outside into a super hard shell while the inside stays a little more flexible. You have to do it quick so we held it over the oil and pretty much snipped the tip of the foil and it slid right in. you can jimmy it around in the oil a little bit till it cools down. Once that happens it’s into the over for an hour at 400 degrees. This step takes some of the brittle nature out of the steel, keeps it from snapping in half when you hit something hard.
 
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black hole2 years ago
Could you post something on making a kiln? The heat-treating part of knife making has always been a problem of mine.
gedion4000 (author)  black hole2 years ago
there should be a few instructables on here on how to make a kiln and there's a lot online. this one was made from a scrap kiln that was found on craigslist. it didn't work, but the bricks were still good. they were stacked up to form a long tunnel(one end sealed up, the other open) with one of the bricks on the bottom cut to allow the flame to enter. everything was held together tightly by a box made out of tin sheeting. our fire came from a turkey fryer and a propane tank. if you want to make a smaller knife you can always make a small kiln by just stacking the bricks up around it and using a blowtorch. it will be some time before i could do an instructable on that so i hope this helps. what issues were you having with the heat treating? was it just a lack of kiln?
Yeah, it was mostly because I didn't have a kiln. So far, all that has happened when I try to heat treat is part of the blade gets to the right temp and then when I try to heat the what's left, the first part cools down. Of course, I'm just using an old (think 30+ years old) propane torch, so that must be a big part of the problem.

I'll poke around and see what I can see.

Thanks for the help,
black hole.
gedion4000 (author)  black hole2 years ago
yeah i would look into getting some kind of high heat insulation. its kind of a cheap way out but if you cant find any fire brick, you could always get a bunch of torches, buy a pizza, and have some friends over to help lol
Thanks ; )
(removed by author or community request)
we did that too, you cant relly see it in any of the pictures but inside the oil there is a little basket the knife lands in we uced to swirl it around. on my knife the first head treat didnt take so i put it back in without the foil on, it was much easier to grab it out and go stright into the oil with a pair of tongs.
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