Should I HT in forge or oven or both? (now, WID)

[weo]

Hello all. I've got a few blades ready to HT and now that I have more than one option, I'm not sure the best way to balance fuel efficiency v. blade stress and would like opinions from those who know more than me (which is probably most of you...)
I was using my forge with a 1/8" thick steel square tube to hold the blades and thermocouple out of the burner flame and tempering in my oven. I've now got access to an Evenheat and am wondering if I should use this for the entire operation because of the potentially more exact(?) temperature control. But this would involve the blades remaining at room temp after quenching for 1-2 hours while the Evenheat cools down from 1475-ish down to 400.
Or I could use my forge for the quench and have the Evenheat be at tempering temp to start tempering immediately after hardening.
The steels I work with almost exclusively are billets of 1080 and/or O1, and 15N20.
Thanks

 

[Josh Rider]

I like to heat treat in my kiln and go straight into tempering unless I’m doing cryo.
I don’t temper in my kiln, I use a toaster oven that has some stuff to keep it steady at whatever temp I’m shooting for.
I like having a forge too though because you can normalize and thermal cycle quicker.
Then go to the kiln for precise temps and soaks.

 

[SBuzek]

I do all my austinizing in my kiln, carbon steel goes into toaster oven at 350 for snap temper till kiln cools down. Can't beat exact temps in the kiln.

 

[Gene Kimmi]

I do the same as SBuzek. 2 hours in the toaster oven after quenching at 30 - 40 degrees below my target temp. Once the kiln is cooled down, I go 2 more 2 hour cycles in it for final tempering. 6 hours may be overkill, but it works for me.

 

[Willie71]

You can put a toaster oven on a thermocouple and pid from auberins for temp control. I have a kitchen oven in my shop for tempering. I used my actual kitchen oven for years.

 

[weo]

Thanks guys! I never thought about using my old toaster oven as an interim while the kiln cools. I've now got a plan for tomorrow.

 

[Ken H>]

Can't beat exact temps in the kiln.

My toaster oven holds closer temps than does my Evenheat oven. Perhaps I shouldn't say that, I've never really checked Evenheat at 400°F range to see what it does. My toaster oven holds ±1°F all day in the 400°F range. I use PID control and that really makes a different, along with the firebrick for added mass in oven.

 

[weo]

My toaster oven holds closer temps than does my Evenheat oven. Perhaps I shouldn't say that,

If it's true, one should speak it. Funny you mentioned this. I just (and I do mean just, it ended at 11:12) exited a digital demo by knifemaker Bhakti Sa through the NWBA, and I asked the question and he said almost exactly the same thing you did about his Evenheat not holding temps well in the tempering range, and getting better results in his kitchen oven.

So, my Evenheat is set to 1490F, blades just put in for second normalizing cycle, and the kitchen oven is set to 400F with a cast iron skillet in it to act as a heat sink.

 

[Ken H>]

Allow me to emphasize I don't really know how well the Evenheat holds a temp in the 400°F range - never tried it. I've never really had a need of it except for one time with a Musso Bowie and I don't remember that time. It's hard to imagine doing better than the ±1°F of my toaster oven.

 

[Josh Rider]

That’s the same reason I use my toaster oven. It holds temp very well witnessed by oven thermometers and a thermocouple.
I also keep a piece of steel in it that’s as wide and long as the shelf to set the knives on.
That thermal mass keeps the temps very steady.
It takes more time to heat up so I start it around the same time as my kiln.

 

[Cushing H.]

Allow me to emphasize I don't really know how well the Evenheat holds a temp in the 400°F range - never tried it. I've never really had a need of it except for one time with a Musso Bowie and I don't remember that time. It's hard to imagine doing better than the ±1°F of my toaster oven.

Ken - +/1 one degree (does not matter if it is F or C) in anything but an extremely expensive piece of equipment is doing REALLY good....... I would take it and run with it

 

[Cushing H.]

he said almost exactly the same thing you did about his Evenheat not holding temps well in the tempering range, and getting better results in his kitchen oven.

I really do not know the answer to this .... but as I think I have said before .... this could be because the controller is tuned to a much higher temperature? With the higher thermal mass of the bricks and better insulation .... if the heating elements are not just really monsters ... I would think you could do pretty good (but again, that is just a guess/impression).

On the other hand, using the oven to temper would mean re-setting the control parameters every time you shift range, which would be a PITA ... and toaster ovens are cheap .... so I would probably get set up with a toaster oven. Which makes the above comment .... dare I say it? ..... academic.