Electric furnace

T

Tomaz L.

Joined
Jan 20, 2005
Messages
24
A friend of mine suggested it might be possible to build an electric furnace for heat treating. It is an interesting idea but I'm not sure if it's feasible. I have some knowledge of electronics but I never tried anything like it before. Has anyone done anything similar and if so, were the results worth the invested effort and resources?
 
A lot of us old jewelers built our first burn out ovens for casting.They are essentially the exact same thing as a HT oven.Few of us ever built our second oven.A commercial oven is just a whole lot easier.What you need to make one is soft fire brick,a steel shell,and nichrome heating coils.The controller can be bought on Ebay.
While we are on the subject of HT oven ideas,one occurred to me recently while looking at a pottery kiln in a pawn shop.Why couldn't you turn it on it on its side,build some sort of kiln shelf in the center,brick up most of the front and make a small slit door to insert and remove the knives. Seems like it would be cheap to do.I can tell you from experience that using a pottery kiln upright is not practical.
 
I set up and installed a propane pottery kiln last year for some friends ...and the thing ran about $2700 all told. The kiln itself was about $1800 + shipping and by time you add up everything else ...the kiln minder, automatic safety shutoff, pyrometer (nice!), etc., etc., ...$$ ka-ching ka-ching $$. Not exactly 'cheap'. And it's only about the size of a wine barrel. You can get a heck of a heat treat oven for $2700. What kind of pottery kiln are you referring to? Not to mention that they're awful fragile ...just a very thin (very thin) skin of stainless steel over firebrick ...you'd likely damage it laying it on it's side without a custom support stand of some type
 
I built an oven with the help of the British tutorial but I changed things to fit my needs. My main use is carbon restoration involving small castings. I don't have to hold temperature very close so I used an infinite control hooked to a relay so the heating elements draw current through heavy contacts and not through the timer. I scrounged an analog gauge and thermocouple at a junk yard and the soft brick came from an old shell oven I tore apart about 20 years ago. As you see my childhood in a Scotch family has really stayed with me. One of the things I learned the hard way is that the brick should be stacked so the walls etc are 4 1/2" thick and not 2 1/4" thick. I run my oven from 1500 to 1600f for about 3 hr. when I do carbon restore and the outside temp of the steel shell runs as high as 600f . Now in an industrial building on a steel table this is not a problem but in a small workshop or garage it could be. I did not find the project hard at all with the help of the tutorial. I bet with a little scrounging the whole thing would only be a few hundred $ and think of the experence you would gain.
 
The bricks came from our investment casting shell oven that we ran at 2000f all day long and they were stacked the 4 1/2" way. We always used K21s and you could touch the outside of the bricks without getting burned. On my little electric oven I built I may not have noticed the out side heat except the 14 ga. steel covering shell turned a real pretty blue :D
I am working on a tempering oven that will be heated with an electric cartridge heater set in a thick aluminum block that I set in the roof of the oven -- I will let you all know how it works when I lite it up.
 
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