# Heat Treating Oven



## Hawkeye (Feb 12, 2016)

Last spring, while I was still out of my house after the fire, I made a trip with a buddy to pick up  some equipment from an engineer/machinist who was closing down his shop. My main interest was the heat treating oven he had built. I couldn't get his controller to work so I ordered a PID unit from eBay. I had that working, but realized that I had the two elements connected in series. (Comes from the lag between ordering and receiving the PID) When I connected the elements in parallel (9.4 ohms - 25.5 amps @ 240 volts, over 6000 watts), the 40 amp solid state relay blew.

I finally got the oven running today. This week, I bought a 50 amp SSR at the local electronic supplier. It does a nice job, working with the PID.



The process of setting up the PID controller included making a large aluminum heat sink ...





The attached SSR is the one that blew.



I built an aluminum enclosure to fit.





Here's the oven mounted on the stand that used to carry my ZX-25 mill/drill. The small display is a thermocouple gauge that I was going to use for the oven I was building before the fire. It reads in Fahrenheit, while the controller reads in Celsius. I thought it would be useful to see both at once. Unfortunately, the small one reads a LOT higher than the controller. As the saying goes, "A man with a clock knows what time it is. A man with a hundred clocks is never quite sure." I'll have to find a way to calibrate the whole affair somehow.


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## Kennlindeman (Feb 12, 2016)

A oven like this is on my bucket list. Nicely finished off Well done


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## rgray (Feb 12, 2016)

That looks very well built. Are those silicon-carbide plates lining the interior?
Over 6000 watts....whew ..I thought I was a crazy person with 5236 watts?


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## Hawkeye (Feb 13, 2016)

As I say, I didn't build it. I wish I could remember which forum the original build was posted on. It was an interesting read before I went to pick it up. The top barely gets above ambient after the heat has been on for some time.


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## Flammable_Solid (Feb 13, 2016)

Nice furnace.  What you need to do is called a furnace survey.  It involves measuring the temperature at various places in the furnace to determine your working zone.  Calibration is done by checking the control thermocouple output with a multimeter and adjusting the offset in the controller.


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## Billh50 (Feb 13, 2016)

Nice oven...I sometimes wish I had one. I do know there are a few really nice plans on the internet for making some nice ones. I have downloaded some of the plans with material lists. Just don't have the money to make one though.
Being on what they call a fixed income really sucks! When I was working I had a take home twice what I am collecting.


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## TommyD (Feb 13, 2016)

Pyrometer, infrarad or with a sensing head.


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## Ironken (Feb 28, 2016)

My first post......We purchased my wife a heat treating furnace this week. She calls it a kiln for her glass projects.....silly girl. It measures 15" x 6" and is digitally controlled with multiple ramp up/down times along with hold times. It was less than $900 shipped.


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## gi_984 (Mar 13, 2016)

IR,
     What brand and model?


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## Ironken (Mar 13, 2016)

http://www.delphiglass.com/metal-clay/firing-tools/delphi-ez-pro-15-6-kiln

Price went up a bit....$964.95


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## Hawkeye (Mar 14, 2016)

Yeah, there should be lots of times it's not being used. You should be able to slip the odd tool into it.


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## Ironken (Mar 15, 2016)

Indeed, Hawkeye. That's a pretty sharp looking build you got there!


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## Hawkeye (Mar 16, 2016)

My only problem right now is that I can't think of anything to make that needs treating. That will come soon enough.


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## TOOLMASTER (Mar 16, 2016)

my electric bill is high enough...


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## Ironken (Mar 16, 2016)

Hawkeye, it's all about capability! You now have the capability to heat treat.


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