I found a treasure trove of information regarding the care and feeding of an electric kiln/heat treating oven:
panaceabeachbum, your a true craftsman.. you make it look easy but I'm not fooled.. great job. Dont forget, you measuring air temperature not part temp, those radiant heaters overheat the part pretty easy if they are line of sight..
excellent point. maybe a diffuser plate or baffle to block the radiant heat ?Originally Posted by twistedneck
Another supplier of Kanthal A1 element wire:
They sell it in cut lenghts and by the pound.
Rich, can you confirm the wire diameter you used? The closest I've found is 17AWG which is .045"
I am almost positive I used 17ga, it measures .0445 so that sounds right, I bought 1 pound on ebay which is aprox 225 feet for $16 delivered, the company I posted the link for gets about $32-$36 a pound So far I have wount 4 elements at aprox 14 feet of wire each and there is still a bunch left so the 50 foot rolls in your link would be ideal to wind 2 elements and have a spare. The resistance wire comp also has a decent tech section which list feet per pound of various wires and resistance per inch ETC.
looking at ready made 110 volt elements I figured the element needed a resistance of 6.5 t0 7 ohms, two wired in series for 220 volt
Cool, you're earlier post said .047" which falls in between 16 and 17 gauge wire.
One more question, is your frame welded up solid?
Most of the commercially available kilns are designed so that they can be taken apart. Due to the fragile nature of the fire bricks, this seems like a good idea as it'll make it possible to replace damaged bricks as the need arises over time.
I just glued two bricks end to end, cut it to 11" long and dug out a channel that the receiver sits in. kiln elements are on the side walls so they dont over radiate the part.Originally Posted by flopshot
This also helps keep the heat in when you transfer it to the quench.
That's for sure, i have damaged brick corners already too. Not to mention the elements tend to wear out much faster if they have excess carbon, oil smoke, burning surfaces, degassing stainless pouches, etc.. Argon pumping through doesn't help matters because it wont add to the protected oxide layer. That's why i run my kiln w/o argon when possible. And i stopped pack carburizing because it made a black plume in my basement.Originally Posted by Tailgunner
We used gaseous nitrogen when I worked at Sierra.
Freedom is not free. Some will perish to preserve it for the many. Just as our Forefathers did before us, we must take up the battle and not waver. Victory is our only option.
Nitrogen will also eat these elements.. its somewhat of a reducing atomsphere too.