Introduction: Homemade Electric Kiln

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

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.

Comments

author
Sure+Hacksalot made it!(author)2014-12-09

Thank you for this Instructable - it was one of the key documentations I needed for making my own so that I could make my fiance's engagement ring (https://www.instructables.com/id/Casting-Rings-From-Startup-to-Finish/).

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author
Wolfgar77 made it!(author)2014-12-10

that is awesome! You are the first to post one! Do you have an instructable for your ring? That is a cool setting- did you make it out of Pmc clay?

author
Sure+Hacksalot made it!(author)2014-12-10

Yes, I detailed the ring making, kiln build, vacuum chamber construction, and the necessary step-by-step guide to all (see the link above). I actually ended up 3D printing the initial ring using a polyjet printer available at school and then converting it into wax using a rubber mold (the 3D printed parts didn't burn-out the best) before casting.

I would have had a much harder time with everything without your instructable!

author
Wolfgar77 made it!(author)2014-12-10

sorry, I didn't see the link:) - I love the PID controller! That is a nice upgrade-I'll have to add one to mine. I make jewelry also but I'm old school. I want to learn the lost wax casting so I'll be visiting your instructable often in the future. Congrats on your engagement!

author
desperate+dan made it!(author)2015-07-24

This is a great idea; but you have to do your sums, I was looking for a place to cast some gold, on a one off basis. Couldn't find anywhere so next choice was looking for second hand equipment with the idea that I could sell it on afterwards but there is very little available in the UK. So next idea was ok I'll make my own, what do I need, a kiln that will let me both burnout wax and melt gold. Perfect your kiln will do both. But if im not using a centrifugal casting system then I need a vacuum table for both the investment and pouring the metal that's ok I can build both.

Then I discovered casting houses! Yes their gold price is higher than Cookson or Rio grande but the overall extra cost is a fraction of the cost of building your kiln let alone the vacuum table!

So as much as I would like to cast the two items ill get a much better quality job done for less money with a casting house.

Dan

author
Sure+Hacksalot made it!(author)2014-12-10

We're on Hackaday!

http://hackaday.com/2014/12/10/casting-engagement-rings-or-other-small-metal-parts/

author
snipperdoodle made it!(author)2015-03-17

That is amazing. I used this kiln to make my fiance's engagement ring too but I didn't document it like you did. I will definitely be using your walk-through to improve my process for when I start making the wedding bands! Thanks!

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RobBBorger made it!(author)2014-01-05

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.

author
altomic made it!(author)2013-10-18

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 made it!(author)2013-10-04

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

author
Jugfet made it!(author)2013-10-03

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

author
Wolfgar77 made it!(author)2013-10-03

Thanks!

author
probablepossible made it!(author)2013-10-03

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.

author
mssadnblue made it!(author)2013-10-03

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!

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Wolfgar77 made it!(author)2013-10-03

You are more than welcome. I was in the same boat! Necessity is the mother of invention.

author
bonecholampworks made it!(author)2013-10-01

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!

author
Wolfgar77 made it!(author)2013-10-01

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!

author
ArpitK13 made it!(author)2017-03-15

In muffle furnace, the test sample is kept
away from any other element that can affect the result of the test such
as fuel of combustion, ash from burning, the smoke of burning.

http://newmeditech.com/products/lab-equipments-products/muffle-furnace/

author
JerryM108 made it!(author)2017-02-14

wolf; exciting challenge for me to get my kiln finished, but......

just wondering about the Kanthal coil. I must assume the coils overall length on my mandrel is 19 inches (not including the pigtails) correct? Also, as stated, the coil should be 3/8 inch, meaning the o.d. of the coil is 3/8"?

Thanks for your inspiring creativity!

author
Wolfgar77 made it!(author)2017-02-15

yes, to all of your questions. Just don't stretch it out too much when separating your coils or it will be too long. My outside diameter was a little bigger when I ended up making my own coil because my mandrel was 1/4" and the width of the wire pushed it up slightly over 3/8". I just filed my channels down a little and it fit fine. I think the last element I made was about 18 inches. You don't want to go much shorter than that or the kiln will heat up too fast with too little resistance. Please let me know if this helps and how your final kiln turns out!

author
JStuyfzand made it!(author)2015-10-29

Hello sir, I was wondering how much watts this furnace uses.

I am making a furnace myself and I can only use 1500-2000 watts due to my outlets having a max of 16A AND the group being connected to the living room and fridge.

So there are little amps left for me.

My furnace (Foundry) is 0.15 cubic feet, do you think this is enough to heat it up to Alluminium melting temperatures?

author
Wolfgar77 made it!(author)2017-01-06

Probably not. I'm not an electrician, but I have mine in the garage and I can barely run anything else on that circuit without tripping the breaker. On dedicated circuit you will have enough heat to melt aluminum though.

author
c0rv0 made it!(author)2016-02-28

this furnace itself is overkill for an aluminium furnace. Honestly you could make one out of a steel bucket hair dryer plaster of Paris and sand and melt aluminium with charcoal or modify it to use propane. Trust me, that kind of furnace could melt steel if the coals are hot enough

author
Wolfgar77 made it!(author)2016-04-05

yeah, well, tell me how well you can use metal clay, or glass enameling with that design and get back to me. This kiln has multiple applications besides melting aluminum.

author
JStuyfzand made it!(author)2016-04-08

The thing is, I need it to be electric!

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Wolfgar77 made it!(author)2016-04-08

I am in the same situation with my electric. You could make the coil shorter ( like 16 inches and stretched to about 29) and that way it won't draw more power. Keep in mind it will heat up faster. This was made to run on 110V. Just make sure you use a variable control and then you can control the amount current coming through and also the temperature.

author
Xnight made it!(author)2016-04-07

I wonder if I could use the components from a heating gun (element + circuit board), remove the thermal fuse, and plug it directly to a wall outlet? The element is 1500W.

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Wolfgar77 made it!(author)2017-01-06

if your coil is too short it will heat up too fast and the temperature will be hard to control. It may just heat up and burn out the coil. You definitely don't want to plug it directly into a wall outlet. Get a controller.

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Sunnyent1373 made it!(author)2016-09-12

I'm trying to build a furnace to burnout gold, and silver will this kiln be able to do that?

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Wolfgar77 made it!(author)2017-01-06

It should, yes

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thebrasscog made it!(author)2016-10-20

Could you use a Yeeco AC 110V 4000W SCR Voltage Regulator Speed Control Driver Dimming Dimmer Thermostat Governing Temperature Governor Fan Motor Controller instead of a variable controller

author
Wolfgar77 made it!(author)2017-01-06

No, I don't think so. I have since done some asking around. What you really want is either a PID controller (read some of the comments above) or an Infinity Control Switch (ICS kiln controller). Sundanceglass.com has one for sale.

author
ParagonShepard made it!(author)2015-06-18

How are people terminating the Kanthal wire? I am not seeing ceramic terminators that isolate the electrical wire from the kanthal wire. obviously you want steel between the copper and kanthal. Does anyone have recommendations?

Thank you!

author
Wolfgar77 made it!(author)2017-01-06

I updated the instructions to include an easier way to do this. There are brass connectors you can buy from some of the ceramics suppliers. I just used some steel bolts with two nuts to separate the wires.

author
JoeE40 made it!(author)2016-11-07

I just finished building this kiln. I bought two silicone-insulated wires (which can withstand up to 600 F), stripped about two inches of each, joined them with a screw terminal thingy from the hardware store, then wrapped everything in several layers of fiberglass for (electrical) insulation. The idea was to create a sort of air-cooled bridge.

I don't know if you really need to go that far; the silicone insulation may be enough on its own to withstand the heat. But since this was my first time building a kiln I decided I'd err on the safe side (and maybe redo it later).

author
imakestuff97 made it!(author)2016-08-31

I use copper split bolt connectors as recommended in this book. https://www.amazon.com/Electric-construction-potters-Robert-Fournier/dp/0442301340

author
Wolfgar77 made it!(author)2015-10-26

The ceramics store gave me steel crimps. I found that they heat up the copper wire too much though, so I recently added a screw and nut to the connector to dissipate the heat. I will update the instruct able with a picture soon.

author
JoeH22 made it!(author)2016-09-03

Thank you for posting this - I would like to build one, but have questions about the PID - SSR - Thermocouple type needed. Have searched ebay - amazon and the likes and find lots of units and youtube videos on what has been used for kilns and other applications (all units mentioned seem to no longer be available), but cannot determine exactly what I need to purchase for a 2000 deg metallurgy kiln similar to yours. Also found video on winding Kanthal wire and sources, knowledge and so I feel confident to make an element. Any suggestions would be greatly appreciated.

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Wolfgar77 made it!(author)2017-01-06

Hi again--i will post a new instructable soon on my next kiln that has instructions on how to wind an element. It is real easy though.

author
Wolfgar77 made it!(author)2016-12-04

Mine is a K-type thermocouple. I don't have a PID controller on mine, so i cant help you there. Look at some of the links in tge comments. Others have put pid controllers on theirs.

author
RDeUslar made it!(author)2016-08-12

Hi! thanks for the instructable i've just finished mine and i'll post photos one is all finished, i have a question though what gauge is the aluminum door, i didn't found any on Home Depot here in Mexico, so i went to a specialized sheet metal store, i found that they have many gauges of the sheet and since it's aluminum i was wondering which of these will work better for the door.

author
BenjaminD92 made it!(author)2016-12-03

Thanks so much for these amazing instructions. But I'm a bit unsure that aluminium is the correct material for the door. Surely aluminium has too loo low a melting point (660C), whereas this kiln goes up to 1000C. Why isn't the door melting?

author
Wolfgar77 made it!(author)2016-12-03

Because it is insulated with Kaowool. Lol

author
Wolfgar77 made it!(author)2016-08-15

Hi, I'm not really sure the gauge on the door. I'm guessing about 22 or 24. It doesn't really matter as long as you can bend it with your fingers. Too thick and you will need a metal brake to form it.

Hope that helps.

author
RDeUslar made it!(author)2016-08-15

It sure does! At least I have a reference, thank you very much again!

author
imakestuff97 made it!(author)2016-08-31

Great instructable! There is an out of print book available which goes into a lot of depth for those interested. https://www.amazon.com/Electric-construction-potte...

I use a Bartlett Controller and solid state relays. I also used copper split bolt connectors where the elements connect to the electrical cord. I purchase my element wire from Duralite.

author
dougstrickland made it!(author)2016-06-19

I'm curious about your router. Where did you get it?

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Wolfgar77 made it!(author)2016-08-15

Home Depot

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dougstrickland made it!(author)2016-08-15

Is it the DeWalt?

author
Wolfgar77 made it!(author)2016-08-16

Ryobi

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