Hay all I am trying to build a Kiln (Heat treat oven) for my knife making so that I can temper my blades but I am no electrician and I need help figuring out how much resistance I need in the coil that will be heating the oven I'm going to be running it on 220v the oven inner chamber dimensions are 31,1/2 inches deep 8,1/2 inches wide and 6,1/2 inches tall the coil slot is 11 feet long the inner diameter of the coil I made is 9.5mm I wrapped the wire around a 3/8in metal rod and the kanthal wire is

• 16 AWG, Average wire diameter: 0.0508 in. (1.29032 mm), 0.324 Ohms/ft at 68°F
• ALLOY: Kanthal A-1 (22% Cr, 5.8% Al, Fe balance). Rated for temperatures up to 1400°C (2550°F).

I am going to be heating this oven up to 1500- 2000 degrees and I need it to hold temp as evenly as posable for as long as posable Thank you

 

You need to throw in some periods into that mile long sentence.

 

ok sorry, but can you help me with my problem?

 

You already have your heating wire & trough so it's too late for asking how much resistance you need. That is something you figure first, then design your oven to hold the required amount of heating wire.

Just going by what I've seen in other kiln's it looks like you don't have enough heating wire for the size of your oven so I'd do the math before going any further. Have you calculated how much heat you need to generate? The long narrow shape of your oven has a lot of exterior wall space compared to a square or round shaped kiln. If you search for "calculating heating wire for kiln" there are websites that will step you through the process.

Just quickly looking I've seen a recommendation of 1.3 watts per square cm of oven wall area but depending on the insulation you could get by with .6 to 1 watt per cm. Just quickly it looks like you have about 6'800 square cm of wall area. I hope you have a 40 amp circuit for your kiln.

 

I measured the wall surface in inches and it came out to 1,004 total surface space and I planned on running it on 220v not sure on the amp or how to check for that the breaker is a 50amp I use on my welder and the wire is made but not stretched or cut to length

 

If this is going to be running in a house your voltage will be 240v, not 220v. If you use 220 for any calculations it will throw off your numbers. 240 volts on a 50 amp circuit (40 amps continuous load) is 9600 watts. (240 x 40 = 9600)

You will need to figure out some type of control if you want to maintain a temperature. If you just connect the kiln to power without control the temperature will just continue to climb. (runaway heat) If you want to keep the temperature as close to your set point you will likely need a sophisticated controller.

 

After you run the calculations for your oven you'll have to see if you have enough wire length to get the wattage you need. I would not go too low on wattage. The oven will take longer to come up to temp and it's temp will take longer to recover after you open the lid. Extra horsepower is good so the oven can come up to temp quickly and the controller will have some extra headroom to work with.

 

 

Got it all finished and it works great, thanks for all the help you all didn't give. You really helped not at all!

 

Your welcome. Couldn't have done it without you.

 

I suppose we could change the name of the forum from "Do It Yourself" to "Do It For Me".