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Tempering with a deep fryer?


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 This idea suddenly poped in my mind. Would it be a good way? The thermal mass of the oil would keep the temp more stable? I know I should use a thermometer as the thermostat probably isn't accurate. 

Anyone ever tried this?

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It does indeed work, it's just messy.  At a knife class I took long ago we tempered a batch of 12 blades in a pot of oil atop a coal forge at 425 degrees, which was messy, dangerous, and interesting regulating the blast to hold the oil at that heat for an hour.  And at the 2016 Ashokan seminar a couple of guys tempered some sword blanks by deep-frying them in a shallow pan of oil in the firepit, and the same held true.  

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I have done a lot of tempering swords in oil at 250C. it works...... however I have had the oil rise up out of the tube and try and attack me a couple of times . I was not injured but 250C oil is no joke  .so I have given up on it as a bad job for the moment.

 I believe one time it was moisture and one time (rapidly)  expanding low temp  oil from the quench, both times tall the oil in the  tube was dumped.  so please be aware of the dangers (especially moisture).

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And be very careful if you attempt this outside if there is any chance of it raining i wouldn't even think about doing it.

Edit: A deep fryer inside would be the best way. This is referring  to the pot in the fire method.

Edited by Jeremy Blohm
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I have a hijack on a similar note

Way back before I bought my gasser I was scrounging for any parts that might have been useful to build a forge. I was doing a remodel of a former restaurant and ended up making some extra by hauling away (to my shop) a defunct restaurant sized, propane powered, deep fryer. As near as I could tell it was the digital control that went toes up on it. My thinking was "well there's a ribbon burner, I think the solenoid/valve still works. There's plumbing goodies and besides that there is about half an acre of sheet stainless for cutting out patterns if all else fails."

I am still convinced that I am just one flash of inspiration away from an "AHA" moment that will transform the thing into something useful for knifemaking.

Any ideas ?

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Joel and Vern,  A lot of makers use liquid tempering systems. These are typically called salt pots and use low temp molten salt in what really amounts to a pot full of hot stuff with a temperature controller. (Thermocouple and PID setup). I'm not sure what either deep fryer is rated for in terms of temp or whether it can handle the molten salt without disintegrating, but with a decent temperature controller, I would think any stainless steel pot should work.

I have all the parts for a tempering salt pot, I just haven't found the time to build it yet. I like using O-1 and that steel is very responsive to salt heat treating. You can buy the salts (high or low temp) from here: http://hightemptools.com/salts.html

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commercial fryers are going to be made to run in between, say,  350-500f. So, perfect for tempering. If it's metal, and meant for food prep, it's most likely 300 series stainless. I have no idea what the heating elements are made of.

I have seen passivated stainless rust, albeit after two years of constant exposure to light steam, salt, and acid. So some kind of liner may be in order. 

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I have been "warming" to the oil tempering idea for a while. Playing it off the idea of getting a TurnTex "Oven Tamer" for my tempering toaster oven to get a more consistent heat. The sand pan is "OK" but ....OTOH that whole fryer would be more capability than I can take advantage of. If I could get the thermocouple and controller to work with the plumbing I would most likely shop around for a replacable "liner/pot" to match my need, size-wise, without "swatting a fly with a sledgehammer".

After I got my forge I had thought about figuring out how to insulate the snot out of "the beast" and rigging up the controls,  maybe a blower, building a lid and trying it as a propane heat treating/hardening oven.

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5 hours ago, Doug Lester said:

That looked like maybe a cup of water that he added to the burning oil.  Can you say "don't do this at home" boys and girls.

Doug

Out door turkey fryers are really dangerous. Every year some dip s#!$ tries to fry a turkey when its raining and ends up in the ER with massive burns. My uncle was almost one of them!

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43 minutes ago, Jon Cook said:

I've taken to putting my quench tank (bread pan) in the oven with the blade in canola to help counter the cheap thermostat.

I can't get what makes that better than just a sand tray ?

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