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Connor J. Myers-Norton

Bacon that no one wants

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So I'm making my second ever chiefs knife and the quench resulted in a left hand warp (which I remedied out of the quench) and the edge turned to bacon (wiggles). The blade was close to final demensions(really close) and I may have over heated it some. I just want to know if I can fix this or if I have to start over, I'll get pictures after I finish tempering it.

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Yikes, that looks pretty bad. I'd check for cracks as well. All in all, if it was me,my first idea would be to grind it out. Since you said the dimensions were really close, grinding doesn't seem like an option. As far as I can tell, your best bet is to bend it back. However, I don't think that'll work. It looks like your may have to restart the heat treat.

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I think you'll need to grind away some of the edge until it's thick enough to establish a centre line, and then grind out the warps. I can't imagine you won't encounter the same problem again if you try to re-harden it...

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If the heat treat is good, other than the bacon edge, I would re-profile it into a smaller knife. How thick was the edge before the quench? I leave it about .025", but I only use deep hardening steel, so a less severe quench. If I was doing a knife that needed a fast quench I would probably leave it thicker.

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It was differentaialy hardened, making the hardened area about 3/4 to 1/2 inch in places, I think I'll re normalize and try again with a slightly thicker edge and no clay other than a thin protective coating.

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I have had this issue before with really thin knives into the quench. Never managed to get it right and since I have just quenched them thicker and ground afterwards with very thin blades. I'd say either cut it down into a smaller knife or chalk it up to bad luck and try again :(

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I've had bacon edge too. Never did manage to fix it if it was bad. However, I did see that my pal Jeremy Spake had worked it out the other day.

 

Here's a quote from him, after fixing a bacon edge 52100 integral chef knife.
"I threw it back in the furnace for normalizing heats at 1500, and pressed the warpy portion on my flat dies, which got a lot of the wiggle out. Did three more heat/cool to black cycles then did my quench. After an 8 count I pulled the blade and clamped as tight as I could in the quench plates that I use for stainless blades. Checked the hardness at 65/66 so I'm pretty happy!"

So, if you have a press and some quench plates, this sounds like a pretty workable method. I kinda facepalmed after I read it, like "duh" but then I remembered that the last time I had bacon edge, I had neither press or quench plates yet!

 

Here's something I have thought about... bacon edge happens if the edge is too thin, especially if the spine is significantly thicker, and especially with clay on the spine. If one was to brush a couple thin coats of satanite over the edge portion, to simulate a slightly thicker edge, perhaps one could HT a thin blade like that without ripple.

 

Actually I have a W2 bacon edge integral chef in my mistakes drawer... think I'll bust it out and see if I can fix it!

Edited by Salem Straub

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Old saying here, forge thick and grind thin! Leave enough meat in the blade to resist warping. You can always grind it down to it's final thickness a lot easier than having to work like a dog to get warps out.

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Its always fun to experiment. Trying to get the blade as close as possible to save time with grinding and finishing to save work is every bladesmith's dream. But sometimes the old ways work the best. The less meat you have, the more flexible the blade will be and you'll have more severe warping. The quench plates are a great idea. But they will mostly work on the spine and overall straightness. A thin edge will still warp.

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