Advice for a 120v DIY kiln?

J

James Hall

Joined
Sep 18, 2013
Messages
85
Hi guys,
A while ago I worked out a deal and got 12 firebricks, an element, infinite switch, and a thermocouple. I made a crude but functional kiln for a while, which seems to work with carbon steel. The thermocouple quit on me the other day, and while ordering a new one I figured I might as well shape this thing up a bit and hopefully get some more consistency out of it (and get it to heat up a tad faster). I found plans that look good to me, but I'd want to scale them down a bit for use with my current supplies and ever-shrinking budget. Does anybody have some advice on this type of thing? It would be greatly appreciated.

Plans in question: http://www.freewebs.com/knifemaking/HEAT TREATMENT FURNACEbackup2.pdf
 
That is a good build tutorial. Just remember that it was for 220VAC. You need to wire your setup accordingly for 115VAC. Your coil should be the right size, or it won't heat properly. If rebuilding it anyway, why not add PID control for more accurate HT.

I wonder why the TC died? They last a long time normally. Can you post a photo of the TC you used? It should be 8 gauge type K for best life.

A 115VAC kiln will heat slowly and only go so high, so don't expect a huge difference, but a tighter and more robust build is always a good thing. 220VAC would be a lot better - Is there 220VAC available in the shop or within 20 feet ( clothes dryer)?

BTW, it is virtually impossible to re-use the old heating coil in the new kiln. Get a new one.
 
Here's the TC.
hrS6a4x.jpg

I got all the parts from a glassblower, so I trusted that everything would work with the necessary temperatures. He actually gave me a 220 element, but the only outlet I have for it is outside. The 115 element is pretty much new, so I'm not too worried about it (or I'm just being stubborn).
 
That TC isn't really what you want for a HT oven. It will work, but is very light duty for something that will sit at 1500°F for long time. An 8 gauge Type K TC and reading unit would be far better.

Once a heating element gets fired, it becomes hardened. Any subsequent movement or bending can easily break it. Even if you got it re-installed in one piece, it would likely fail soon.
 
I ordered a heavier duty type K and digital readout that should arrive today. IIRC, the source on bending elements said to heat them with a torch to make them pliable. I think I'll try it, only because I'd be ordering a new element anyway. I appreciate the help, as always.
 
I got a welding extension cord 75' long to run to all corners of my shop, as I didn't run 220 plugs when I had the shop wired. I only wired 2 plugs for the welder and compressor. I will probably change a few circuits this year, as we used heavier guage wiring as I used to breed reptiles and carried high loads on the circuits.
 
LOL!

In all seriousness, I bred quite the variety of snakes and lizards. It was an interesting hobby.
 
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