Accurate, low-cost tempering oven?

SBuzek said:
Dave I use my evenheat to temper but it does take about 45 min to come down to 400 deg. I use a cheap toaster oven set at 300 deg. that has a coule of pieces of ceramic tile inside,I turn it on about 15 min before my hardening cycle ends, out of the evenheat onto the quenchplates,down to room temp unwrap and check for warp.into the toasteroven,leave the door open on the evenheat and let it cool in abot 45 min I close the door and check temp, pull the blades out back onto the quench plates to room temp then into the evenheat for 2 hrs. Back to room temp and then back into the evenheat for another 2 hrs.
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Damn, I can wait until the paragon is down to 300 degrees and it will quickly rebound above 500 degrees regardless of what temperature it's set to for the tempering. It's not the end of the world, but it would be nice to be able to do what you're doing with that Even Heat. Thanks for the info!

Regards,

Dave
 
Dave,My guess is the evenheat with the larger chamber it has allows more airflow and lets it cool down quicker than the paragon.
Stan
 
SBuzek said:
Dave I use my evenheat to temper but it does take about 45 min to come down to 400 deg.


I hope I'm not messing my Evenheat up, but sometimes I use it to temper, after heat treating in it. I place a fan about 8 feet away from it, and turn it on low (the fan). When it reaches somewhere between 100 and 200 degrees, I reset what's needed. I figure I'm keeping the fan far enough away from the kiln to not hurt it, plus I put the fan on low speed. Of course having the Evenheat door open is rather important while the fan is on.
BUT, alas, I'm sure liking my "Swirl air" :).
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I've seen the plans that were posted earlier in this thread, and gave some serious thought to an idea of a dual chambered oven...

would a two chambered oven, with a double wall of firebricks between the chambers allow one chamber to heat up to austenizing temp, and the other to stay in the 300 - 400 range? That would be a heck of a convenient setup.
 
I just got a Euro Pro convection oven at Lowes. Its digital, and has a timer. Not sure how well it works yet, but my old toaster over started adjusting itself as it heated up. The dial would actually advance as it heated up. Was driving me nuts. This looks like just the ticket.
Ed
 
I'm currently tempering in my home oven with lots of thermal mass added for stability. I may at some point take the calrods out of my old toaster oven, build a muffle out of kiln brick and PID control the thing, I heat treat in olive oil, and rinse the blade between HT and temper, so my wife doesn't mind the smell at all, she occaisionally asks if I'm baking and looks disappointed when I tell her it's a blade not the bread she likes me to bake her

-Page
 
happycat said:
I just got a Euro Pro convection oven at Lowes. Its digital, and has a timer. Not sure how well it works yet, but my old toaster over started adjusting itself as it heated up. The dial would actually advance as it heated up. Was driving me nuts. This looks like just the ticket.
Ed
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Happycat, please update when you find out how well it works. I don't think I could squeeze another appliance into the small shop, but it would be good information anyway.

Regards,

Dave

(Editted to add that I just looked it up and it has a dehydration setting as well. That would be great for speeding up sheath drying.)
 
bladsmth said:
Rocketman - It would be fairly cheap. I would use a dryer element. The walls could be standard thermo board from Darren Ellis.

Stacy
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As an appliance repair man, my first thought would be an electric range surface unit or broil element. General Electric used to make small ovens and the elements are full depth and half as wide. Dryer elements burn out if they don't have the proper air flow to keep them cool.
 
General Specific said:
What burns me is you spend $1600 on a high-end HT oven and can't even use it for the tempering because of the thermal rebound. I'm afraid the toaster oven will be tempering my blades for the forseeable future...
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Newb asks, "What is this temperature rebound of which you speak?"
 
rhrocker said:
So, years later, I'm needing a oven of sorts to temper steel. Since the Wally World one didn't work, I decided to try the SwirlAir. Hey brothers and sisters, this thing tempers great, and all three indicators are right on. It circulates hot air around, to cook your turkey fast, and all the way through. I use the normal
heat treat temps, and so far I've been very pleased. The hot air contacts everypart of the blade instantly, and circulates around it right at the 400 or whatever degrees.
.
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Know now days as a 'convection oven'. They also help with temperature gradients if you are using more than one level of racks.
 
TheHermit said:
Newb asks, "What is this temperature rebound of which you speak?"
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The firebricks hold a load of heat. If you open the door after going to 1500 degrees for the HT and wait 45 minutes/hour and it shows 300 degrees, then set for your tempering heat or whatever (it could be zero degrees), it will still climb back up above an acceptable tempering temperature. And it's not like the damn thing just rebounds, you can plainly hear the relays clicking on and off as if it's actually regulating the temperature. It's no big deal, just a little dissapointing.
 
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