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I Forge Iron

Building my own tempering oven?


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I just replaced my pellet stove, and looking at the old one...enameled cast iron...it occurred to me that it would make a sexy tempering oven.

The only problem is I've never built an oven, or even messed much with electronics.  Very roughly I figured I'd:

1) Rip out all the guts, basically leaving a cast iron body with a door.  I might have to weld on a back plate before I'm done.

2) Put some kind of heating element/coil/flux capacitor in there somewhere, with a steel plate to catch and distribute radiant heat.

3) Add some sort of power switch and controller to the heating element.

4) Hang a thermometer in it, or use a probe and external readout.

 

How hard does this sound?  Do I want to add insulation?  What kind of heating element would I use?  How hard to incorporate something like this to both control and display temperature?

What am I totally overlooking?

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1/  You need some sort of framework to hold the insulation in place. It might be suitable for that. 

2/ There are plenty of suitable elements available. I'd probably use rod-type elements and mount them to the back of a plate to distribute the heat.

3/ Something like the linked controller, switching an SSR, would handle the power control.

4/ Use either an RTD (Pt100), or a thermocouple with a suitable temperature range, that will work with your chosen PID controller.

For your unnumbered questions:

How hard it will be depends a lot on what skills and experience you have at your disposal. 

You will need insulation and it will need to rated for the top end of your intended temperature range.

I'd use a straight rod heater element rated for whatever power supply you have available. You should not need high power if you have reasonable insulation. It seems they either don't exist across the pond (which seems most unlikely) or are called something different Stateside: searching for "straight rod heater" on Amazon.co.uk brings up lots of hits, but on Amazon.com I get none that are useful. They'll bend when new, but seem to go brittle once they've been through a heat cycle or two so reusing old ones may be difficult.

It's very easy if you know what you are doing. It's not too difficult to research it online, though you'll see quite a lot of complete drivel in with the pearls of wisdom. You need to be able to tell the difference.

The best advice I can give on controllers is always the same: DOWNLOAD and READ the manual, from a readily-accessible, non-password-protected website. Only buy if, when you have read the manual at least a couple of times, it makes sense. Do not assume that it "must" be easy and will all make sense once you have it in front of you.

The reason for the download from a readily-accessible website is so that you can ask for help on a forum with a link to the manual. Someone who understands process controllers has a pretty good chance of helping, even if they have never seen your controller. No link, no chance of help.If the manual is not online, buy a different controller.

 

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