# Another lesson learned...I think



## norman vandyke (May 7, 2017)

Tried my first attempt with a home done heat treat. Only tried because the rough blade was laying around from one of my first attempts and I was in the middle of making charcoal in my fire pit. Bottom line, I set it on the hot coals for about 30 minutes, then dropped it into salt water. 

No temp check. No checking for demagnetization. Just heat to very hot and drop in water. I really didn't care of it failed, just wanted to know what would happen. Result, a very brittle blade that is now in two pieces. Luckily, it was just from an old circular saw blade.

Next time, I'll hopefully have my electric kiln ready and a quench tank of oil on standby.

Reactions: Agree 1


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## Schroedc (May 7, 2017)

Yep, rapid cool will do that. I use the campfire all the time to detemper files, heat orange hot and let air cool.

Reactions: Thank You! 1 | Informative 1


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## Foot Patrol (May 7, 2017)

To quench, bring the knife to non magnetic (red hot) and quench it in some canola oil that has been heated to 120 degrees F. Gently move the knife up and down in the oil. Do not move the knife side to side as it could warp. Run a file over the blade, if it skips then its hardened, if it bites you will have to repeat the process as it was not hot enough. Put into a temper oven at 400 degrees for 2 hours, cool and repeat the tempering cycle one more time. Don't quench in water or you will run the risk of cracking the blade.

Reactions: Like 1 | Agree 1 | Informative 2


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## Strider (May 8, 2017)

You'll learn eventually! Good job. The pattern it got from hardening process is sick. Shame it broke but you learn more from one broken bow than five normal!


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## norman vandyke (May 8, 2017)

Strider said:


> You'll learn eventually! Good job. The pattern it got from hardening process is sick. Shame it broke but you learn more from one broken bow than five normal!


Also noticed upon closer inspection that it has numerous small warps along the spine, nothing I couldn't have corrected with a little grinding. But I figured if it was going to warp it would happen more along the edge.


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## robert flynt (May 8, 2017)

Charcoal will get the blade to hot if your not careful. Do not lay the blade on the charcoal, stick it in the charcoal edge down and bring it to non-magnetic. If it get white hot and sparks are coming off of it you may as well throw it away. If you must use water don't use cold water use warm water and do an interrupted quench, which means plunge the blade in the water withdraw the it and plunge again. If it doesn't crack, temper as quick as you can! By the way, if you look at the break in that blade, observe the large crystal grain structure in the break. If you were to break a properly heat treated blade you would see a very fine crystal grain structure.

Reactions: Like 1 | Agree 1 | Informative 2


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## Strider (May 9, 2017)

I agree with Mr. Robert. I see it is a rather thin piece of steel, so the opt version would be plate quenching. Both oil or water may warp it, or even worse, twist it, but placing it inbetween aluminum or copper plates and stand on them ASAP, it will lose any chance of bending and provide a mess free outcome with the same or a bit lower hardness.

Reactions: Like 1


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## Foot Patrol (May 9, 2017)

@norman vandyke another tip would be to drill your handle holes prior to quenching. Once hard it is a PIA to drill holes.

Reactions: Agree 1


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## norman vandyke (May 9, 2017)

Foot Patrol said:


> @norman vandyke another tip would be to drill your handle holes prior to quenching. Once hard it is a PIA to drill holes.


Haha! Knew I was forgetting something.

Reactions: Funny 1


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## robert flynt (May 9, 2017)

Foot Patrol said:


> @norman vandyke another tip would be to drill your handle holes prior to quenching. Once hard it is a PIA to drill holes.


It won't happen unless you use a carbide drill bit!!

Reactions: Agree 1


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