silly heat treating question

[ShawnShaffer]

Ok so I got two sets of leaf springs from my ladies dad and I have recently used a bit to make this knife. my question is since this is a bigger knife and a small propane torch just isn't gonna cut it how long do I leave it in the oven. I know this is a dumb question but the knives i've been making have been a lot smaller so didn't need an oven. I have a picture on here and the blade is 11 and a half by 2 and a quarter wide. thanks for the help

[son_of_bluegrass]

Are you looking for info on using a kitchen oven for tempering after hardening? The time is less important than the tempering temperature, but usually 2 or 3 cycles of about an hour each is generally what is used. But with care a propane torch can be used to "run the colors" for tempering. If you want to use a kitchen oven for tempering, a more important question is "how hot" and that will depend on what you intend to do with the blade, a chopper will temper higher than a slicer.

OR are you asking about hardening? And if so, what do you mean by "oven" since a kitchen oven doesn't get hot enough to austenize the steel for hardening. A heat treating oven will work or this can be done in a forge.

 

ron

[ShawnShaffer]

Sorry shoulda clarified on that i mean tempering after the hardening process and yeah a kitchen oven. i have a nice chili one burner propane forge so i can do the hardening in that but the tempering that follows would be a big help there. I read something somewhere that you would set the oven to what ever temp was needed but you have to add and hour per square inch is that correct? and before i forget i would definately like to know how hot to set the kitchen oven

[GEzell]

I normally temper OCLS steel (old Chevy leaf-spring) at 400f twice for 2 hours each cycle. I let the oven reach temperature before putting the blades in, and wrap the blades with a few layers of aluminum foil in a half-hearted attempt to equalize the heat (likely completely unnecessary but for some reason it makes me feel better). I let them cool to room temp between cycles. I test the edge harshly, and if it shows any tendency towards chippiness, I'll temper it again 15 degrees hotter. Note, not all oven thermometers are accurate, I highly suggest getting and using a good oven thermometer...

 

I like the shape of that blade...

Edited May 2, 2013 by GEzell

[ShawnShaffer]

Thanks guys and i do too starting to look really mean with the bevels ill post a pic or two when i get it done

[B. Norris]

Kitchen ovens are notoriously inaccurate temperature wise. Bury the blade in a pan of sand, cat litter, dirt, etc. anything to provide thermal mass and keep the temperature of the blade more even. When you measure temperature, do not go off the temperature of the air in the oven but, rather, off temperature of whatever you put in the pan. Probe (meat thermometer) type thermometers work best for this. You can leave the knife in as long as you want without ill affect. The temperature you reach makes the most difference, longer soak times make a little bit of difference but, not enough to worry about. Some people like a long temper (2-4 hours) for 5160.

 

~Bruce~

[ShawnShaffer]

again thanks and will do got a 50 pound bag of sand and a pan to put it in. now to find a thermometer.

[ShawnShaffer]

So Mr. Norris question when I do pull the knife out of the oven do I quench them or let them air cool? I used to quench my smaller knives right after a temper to keep the heat from running amok should I do the same or would it not bother either way?

[Alan Longmire]

Air cooling is better. Quenching can cause stresses exactly where and when you do not want them.

[ShawnShaffer]

Again many thanks I just started the file work on this bad boy seen as how I don't have the power tools for it. However I will put up a picture soon.

[ShawnShaffer]

ok so ive got it quenched tempered three times and sharpened up some took it for a test drive and well the kingdom of back yard is safe from milk jug goblins and ents gone awry.