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Tempering in an Evenheat


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Hello,

 

When tempering, should I let the blade cool down to room temperature in the air before starting the next tempering cycle, or is it OK to leave it in the kiln to cool more slowly? It would be quite convenient to program 2-3 tempering cycles in the oven and just let it do it's thing, however it would take a couple of hours to cool down from tempering heat.

 

Thanks.

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It's fine to let it cool down in the kiln. As I understand it (and there are many more on this forum that are real gurus on this), generally speaking, the less stress (i.e. the slower the change in temp) the better. Except for hardening, of course.

 

I temper in my Evenheat in the way you describe.

 

If you're new to Evenheat kilns, be aware of the heat retention. Don't, for example, heat the blade to critical, quench, then leave the kiln door open and wait until the temp reads normal, then program in the tempering cycle and put the blade back in. You may find the temp over 1000 degrees before you know it, totally softening the blade you just quenched.

 

This is, of course, a purely hypothetical example. It definitely is not something I've done myself. Nope. Didn't happen.

 

Grins,

 

Dave

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from what I was told by Kevin Cashen, there might be some small benefit to quenching after tempering, but no harm done by slow cooling other than taking more time.

MP

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As Dave said, it takes some time for an Evenheat oven to cool down from H/T temps to tempering temps. I would be cautious about leaving the door open to cool. This can shorten the lifespan of the elements. Also, it's normally it's best to go from your quench to the tempering oven quickly. The steel after quench is under extreme stress and the sooner that you can relieve that stress, the better off you will be. That's why most will use a different oven for tempering. Something that I would also recommend is to preheat the tempering oven. This helps eliminate hot spots due to the heating of the oven whether it is gas or electric.

 

Gary

Edited by Gary Mulkey
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Thanks everyone! I quenched the blade today, and it appears to have picked up a slight warp. What's worse though is that I heard a couple of "tiks" when I quenched it, so I think it may have cracked. I can see a small line about an inch long next to the spine. I'm running it through two tempering cycles in the oven right now. We'll see how it turns out.

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clamp it in a vice mega tight and flick it with a finger nail to see if it resonates. Usually if i think its cracked I just bend it in a vice they usually just snap into if they have cracks =\

Edited by Gabriel James
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