Is this going to work?

R

Roger

Well-Known Member
I'm building my own oven, did it before as a 110V unit and it worked ok. But I would like a quicker heat-up time and putting the oven itself together is not too difficult. Same with cutting the channels for the coils and the physical part of wiring the PID, SSR plug and a fuse. But to make sure everything will work on a USA 220VAC circuit can someone with more experience than I or some technical knowledge take a look at my very crude drawing and see if the final product will actually heat up without burning down the shop? Thanks.Untitled.jpg
 
I'm not 100% certain, but I believe that the power must run from source to the SSR, and the PID must be wired into it's own power source. I have quench tanks setup with two 110v water heater elements, and I had to run two seperate power sorces to make it work.....one to the SSR then to the "appliance".....the PID required a second power connnection to 110V to operate. At first I tried it the way you're thinking, and it fried the PID. I learned that a PID will handle the Voltage it's rated for, but anything more then 1-2amps and you fry the circuitry.
 
PID I'll use has 90-220V input to it for operation and 3-32V output for control of the SSR. I'm concerned that using the 'relay' in the SSR might not work breaking the N for the two heating coils. I'll also have an off/on switch and main fuse with a K thermocouple in the oven to control the PID.
 
Wiring.jpg
This would be better:
 
Thanks Rudy that thread answers a lot, I now understand what Ed was saying. Thanks everyone.
 
Roger,
You might look at this-http://www.bladeforums.com/forums/showthread.php/985651-Heat-Treat-Oven-Wiring-Schematic-Future-Sticky
It is for a 240 oven.
Fred
 
That is a good schematic for PID controlled oven. Using PID control with SSR will give an oven MUCH better control than the typical SetPro controller.

Ken H>
 
I finished my oven recently. Bought the elements at budgetcastingsupply.com . I used the following element: #7103: 240 Vac Kanthal Heating Element - 2300 °F Max. 1ea CN76000 PID and 2ea NTD2425 Crydom relays. Picked up both the PID and relays on ebay for less than $50. Picked up a high temp K type thermocouple for about $15 bucks.

My oven space is 5in wide x 4.5in high x 17.5in deep. It will heat to 1500F in less than 5min.

I would add that you should incorporate an open-door shut off switch to the elements. If you bump those 220v elements in your haste to quench you might get a very unhealthy surprise. Many of the online schematics don't show one. I have 4 switches 1) main power 2) relays 3) fans over relays 4) door switch.

What a great project that was. Here is the schematic I used.

Heat Treat Oven Wiring.jpg
 
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Thanks for all the input. I fired up my 220V oven last night for the first time and set all the parameters in the PID. Heats up very quickly (10 min or less to 1550) and maintains the heat (+-) 5*. I'm happy, thanks again for the input.

Now for another question. My shop is a small building behind my big shop that's about 100' from the house. Would it be possible to use the heat treat oven to temper as long as it would maintain the lower heat? Can you temper two or three blades at the same time" It would keep the wifey happier. :1:
 
The only problem you will encounter with using your heat treat oven to temper is getting it to cool down in time. Mine can take quite a while to cool down and most hardening/tempering recipes that I have read about strongly suggest getting the blade into the tempering oven asap.

When it is cooling down, you have to let it stabilize at the lower number for 15min or so as you will have hot spots.

Another point to consider is that with 220v coils now in a space built for 110v, they will be a significant radiant heat source. Meaning you may need to give the oven a bit of extra time to stabilize at temp. When I begin a session, I set the oven for 1200F and let it sit for 30min. Then I proceed with my carbon steel recipe.

Enjoy and be safe!
 
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