Homemade Electric Kiln

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I was frustrated with the price of electric burnout kilns for ceramics, metal annealing, glass enameling, and melting precious metals etc,. so I decided to build my own. Most kilns that run at these temperatures cost between $600 and $1200. With a little help from a guy at a ceramics store, I built one for about $120 (not including the power controller and pyrometer). This little electric kiln can get up to 2000 degrees F and is easy to make without any special tools besides a handheld router. I also wanted one that I could take apart and replace the element, since these are inexpensive.

Materials:
1. 8 x 10" bolts with nuts- 1/4" diameter
2. 7 x soft insulating fire bricks (4 1/2" x 9" x 2 1/2"- make sure they are soft)
3. About 7 feet of angle iron from Home Depot (this is the frame) (4 x 14" legs/corners, 2 x 9" floor supports)
4. One sheet of thin aluminum (for the door). At least a 9" by 9" square
5. One 3/8 inch x 19" coiled heating element (stretched to about 28") out of 16 gauge Kanthal wire. I had this wound for me at the local ceramics store. I recommend you wind your own or as a ceramic supplier in your area to wind one for you. In my other instructable, Electric Kiln -Top Loader, I give directions on how to wind your own.
6. One small hinge with screws
7. Fire proof pins (should come with element) or you can make these out of the Kanthal wire.
8. Short outdoor extension cord rated to at least 10 amps (cut down to about 6 feet)
9. Stand alone ICS kiln controller. Sundanceglass.com has one for $84.
10. 1" thick Kaowool- about 1 foot square

Tools:
1. Hand held router with 3/8 inch bit
2. Wrench
3. Needlenose pliers
4. Hacksaw
5. Wire cutters/stripper
6. Drill
7. Tin snips

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Step 1: Cutting the Channels

1. Pencil the channels in as a u-shape 3/8 inch wide. I left about an inch, to an inch and a half from the edge and the top of the "U" so the elements are not too close to the opening of the kiln.
2. Route out the channels with your router using a 3/8 inch bit.
3. You will need to cut one of your fire bricks down to a square 4 1/2" by 4 1/2" for the back and route out two straight channels. This will be the back wall.

Step 2: Putting in the Element

1. You'll need two bricks for the floor, as pictured.
2. The dimensions of the fire bricks are 4 1/2" x 9" x 2 1/2" - when you construct the firebrick box, the kiln will be too wide across (2 outside walls at 2 1/2" and your back wall is 4 1/2", for a total of 9 1/2"). To make the walls flush with the roof and floor (9") you will need to take out a 1/2". In the first pic you can see I shaved off a1/2" from the right side. Any saw can cut these bricks, they are very soft.
3. The element I started with was 24 inches long. Separate the coils of the element so that they aren't touching. If you are unsure of how to do this, then you can always ask the people at the ceramic store. This stretched my element out to 29 1/2 inches. My element cost me about $25.
4. You'll need to drill two holes out the back of the kiln so you can run the ends of the element out the back. These are drilled inside the top channel about 1" apart. Pick a drill bit slightly bigger than your element wire.
5. Thread the element into the channels as shown.
6. If the ceramics store gives you pins, I found it was better to use pliers and make little u-shaped pins out of them. You can push these into the fire brick about an inch apart to keep the elements in the channels. It doesn't seem important now, but when you start firing, the element will want to flex and move around. The pins will keep it fixed in the channels.
**update - There have been many questions about the element I used and where I purchased it. I had hoped people would ask questions from their local ceramics store and get answers there. That is where I had my element wound for me. I have learned a few things since then. The element is a type of NiCr wire called Kanthal. Most Kanthal is rated to about 2450 F. There are other element types if you need higher temperatures. Kanthal is used in low-fire/ceramic applications. Either find a ceramic supplier to help (as I did) or you can contact a place like Joppaglass.com and have an element made to your specifications. They will usually want to know the voltage of the power source, max amperage (my garage is 15 amp breaker) and the gauge of wire (I think mine is 16 gauge). The arbor (inside and outside diameter of the element) can be requested and you can get the element you want.

Step 3: Making the Frame.

1. The frame I designed, squeezes it all together. Cut four 14" lengths of the angle iron with your hacksaw for the corners.
2. Cut two 9" lengths for the bottom. These two pieces hold the floor and rest on two 10" bolts on the bottom.
3. Thread the bolts as shown--4 on top,4 on the bottom. Two of the bottom bolts hold up the floor, the rest just squeeze the whole project together to hold the bricks in place.
4. Remember to place two bricks on top for your roof. Also, you can see that I have the whole project off the floor by about 3 inches.
*Safety tip--never use this or any other kiln on a surface that isn't fireproof. I always have this on my concrete floor in the garage.

Step 4: Making the Door

1. With your tin snips, cut your aluminum sheet into the shape shown in the picture. The dimensions I used make a 6 inch door. The central square is 6" and the tabs are 1 1/2". (So start with square 9" by 9" and cut out the corners)

2. I used a sophisticated metal break to bend the metal (called my fingers and a scrap of wood). Bend the tabs up so you have 1/2" on the inside and the door itself is 1" thick.

3. Cut a 6" x 6" square of the 1" thick Kaowool and squeeze inside the metal as shown.

4. Attach the door with a small hinge. I pre-drilled some holes in the frame and used metal screws to screw it to the frame. I didn't put a latch on this. As an option you could by-pass this step and use another fire brick over the entrance.

Step 5: Connecting the Power

1. Cut an outdoor electrical cord(10 amp) down to 6 feet and keep the plug end. You don't want it too long.
2. Strip the wires and connect to the element wires coming out the back of the kiln. My element came with metal connectors and ceramic sleeves. The sleeves are optional. I have since used small bolts to attach the power. This separates the terminal wires from the copper wires of your power cord and the nuts and bolts act as a heat sink to keep your wires from getting too hot
3. You need to ground this by attaching the green wire to the frame. I just found a small metal screw and attached it to the frame.
4.
**update 1/5/2017: A lot of people have asked me about my green controller. This was from an old kiln and has no numbers or markings on it. I have done some research on the type of controller you will want. They are called stand alone ICS kiln controllers. I have found one at Sundanceglass.com (pic 2 and 3) and have ordered one for myself as a backup for my controller. This is an infinity switch which will turn the power off and on depending on the setting you use and will allow you to obtain an even temperature. Use a thermocouple and pyrometer to monitor your heat and then you will know what setting works for the temperature you are trying to reach. There are some people in the comments that have used PID controllers and they have Instructables on how to wire them up to your kiln. I think cost wise, it is about the same to order an ICS controller or a PID controller.

**Safety tip--Do Not plug this directly to a wall outlet. Also, do not touch the element wires when the kiln is on.


5. I ran a piece of flat iron across the back wall of the kiln so that the back wall has more stability. This is not essential. When I first made my kiln, the squeeze of the frame held the back wall in fine.

Step 6: Finished Kiln!

1. In the original incarnation of my kiln (1st pic) I drilled a hole in the top and mounted an old thermocouple/pyrometer on top of the kiln.
2. I have recently upgraded to a better thermocouple (Pic 2) and directly connected this to the analog temp. gauge on my controller. I was lucky and had one of these from an old kiln I broke. For accurate firing temperatures I recommend a K Type thermocouple with a digital pyrometer. Another option for ceramics or glass enameling would be to drill a viewing hole in the side and then buy a ceramic plug for it.
3. I have run this for many hours at various temperatures (3rd pic). I really have not experienced any problems except my element still wants to pop out of those channels. I"ll just have to keep an eye on them.

Please let me know what you think or questions you have.

**update Dec. 11 2014- I have run this kiln now for hundreds of hours (firing clay, PMC clay etc.) and found the max temperature to be 2300 F.

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5 People Made This Project!

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182 Discussions

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RobBBorger

5 years ago on Step 6

This is great!! Simple and functional. And very well explained, I have no doubt I can make this with your instructions. Thank you so much, I would never be able to afford one otherwise.

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altomic

6 years ago on Introduction

awesome. i want to make so I can blow glass. wondering how I could do it and bam -your instructable. thanks.

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rwlarkins

6 years ago on Step 6

Terrific!!. I have been trying to find an inexpensive kiln for copper enameling for years. Never could afford a store-bought one. Thanks. This appears to be fairly easy to build.

Robert Larkins

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Jugfet

6 years ago on Introduction

An excellent project and so simple!
I'll be assembling one of these soon for smelting Tin (Sn) ore.

1 reply

Thanks! I have been wanting to make -- not a high temp kiln, but a low temp oven for polymer clays, and this instructible gave me insight on how to construct it.

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mssadnblue

6 years ago on Step 6

Thank you so much for showing how to make a kiln! I have been wanting one forever but where I live they usually run $1500 and up -- way out of my budget. Now I will be able to build my own at a much more affordable price. Thanks!

1 reply

Awesome Ible!!!

Expensive store bought kilns have the same problem with the elements popping out - they heat up, expand, and voila, out they pop! (so don't take it personally!)
My paragon kilns have metal staples that hold the elements into the channels - they often come loose and need to be pushed back in, I believe they're just steel - would that work?

Also, for around your door - perhaps a woodstove gasket would work? I've used it instead of foil as a gasket, works great, cheap as hell.

Either way, nice job. Looks a helluva lot nicer than my waffle iron kiln!

1 reply

Thanks- your waffle iron kiln is a great idea and one of the first ones I looked at before building this. I almost built your waffle iron kiln but for some of my projects I was afraid it might be too small. Thanks for some of my original inspiration!

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Ohregano

Question 12 days ago

Could regular fire bricks be used on the top and bottom? Using soft fire bricks on the sides and back.

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gantz4u

23 days ago

Thanks for sharing this. I'm thinking about modifying my store bought kiln to increase it's depth with additional fire clay bricks and heating elements. According to the specs of my store bought kiln the max. temp. is 2350F, So this home made model looks effective in regards to temp. My kiln has a insulation brick thickness of 2.5 inches for the roof and walls of the kiln. The heating element coils are spaced 2 inches apart, starting 2 inches from the floor and ending 2 inches from the ceiling and reaches the max. temp. of 2350F in 2hrs 47min. Since the coils are recessed into the bricks walls, there's 1.5 inches of brick insulation thickness left in these recessed regions. The rotary switch is rated at 120v 15 amps. I think this switch is over rated and the 2 heating elements provide resistance down to around 11 amp of current. The taps off this dial switch are a power in COM and + with a light daisy chained into these taps to indicate on or off and an L1 and L2 tap to provide power to 2 heating elements. Considering the 2 heating elements other 2 legs are wired in series, I assume the 2 legs off of the Dial switch leading to the 2 heating elements are a + and -; and assume the current runs into the top coils right leg, out of the top coils left leg into the bottom coils left leg and back out of its right leg to the switch. My plan is to find an appropriate manual dial switch to run an additional set of 2 heating elements in the original manner and then double the walls height capacity from 4.5 to 9 inches. to modify the kiln. Basically just copying everything thats going on onto the lids lip, running the kilns 2 dials in mirror settings, and unbolting the lid and rebolting onto the new "top". The model is an older paragon firefly manual model (vs digital). Perhaps Some of these stats would help others in kiln design for DIY projects.

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kevincrater

2 months ago

How would you change this to make it deeper, just a longer wire? And more brick?

Awesome design btw, thanks

1 reply
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Wolfgar77kevincrater

Reply 2 months ago

Yes, I would measure the extra distance and just add another brick. Keep in mind that with 120V, your longer coil will take longer to heat up and reach the temp you want...but it should work.

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Uchennayah

2 months ago

Hello I am interested in making this kind of Oven for my burn out during casting and metal smithing. However I will want it to be a gas fire kiln. Please what adjustments can I make to produce a gas fired kiln instead. Thank you.

1 reply
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Wolfgar77Uchennayah

Reply 2 months ago

Sorry, I can’t advise you on that build....

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AlishbaK1

1 year ago

There are many considerations to take into account before you buy a kiln. Buying a kiln is a major expenditure; take the steps to ensure that you will be happy with your purchase for years to come. If you are an active potter, you may even decide you need more than one kiln.There are lots of benefits to having a kiln, and lots of times, you just need to make sure you know how to use it. One of the best kilns that you can get is the Rapidfire Pro Electric Kiln with Digital controller. visit below link for more details.

https://spinningpots.com/the-best-pottery-tools-an...

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Wolfgar77AlishbaK1

Reply 1 year ago

I think you are missing the point of what Instructables is. This is a site of people that like to make things and not buy them off the shelf. The point of this Instructable is that kilns, like the one in your post, cost $500-$1000. You can build one yourself for fraction of that cost!

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FranklinM23

1 year ago on Step 5

Fantastic! I acquired an old home-made kiln without a controller and was completely befuddled on how to handle the electrical part. Your guide and ideas and links for the paragon controller and pyrometer served me well and the guide on how to wire was priceless. I know I sound amazed but you saved me $500. for a new kiln. I was afraid to fix this old one until I read your guide. Thank You!

1 reply