For his Hackaday Prize entry, [Matt] is building a small kiln for melting metals and firing clay. He’s making this kiln out of materials anyone can acquire — dirt and a bit of nichrome wire.
Most kiln builds you’ll find on the Internet use fancy refractory bricks and other materials you may not have in your back yard. [Matt]’s project is entirely DIY, and starts with a large pile of dirt and rocks. Aftter shaking off the sifted dirt, washing the rocks, straining off the gravel, getting rid of the sand, and siphoning off the water, [Matt] has a big bag of wet clay. This clay is mixed with perlite, an insulating, refractory material, molded into bricks, and fired. The result is a brick that looks good enough to be made into a kiln.
[Matt] has already put a lot of work into the calculations required to figure out the heat transfer of this kiln. At best, this kiln is going to take 14 hours to get up to temperature. That’s incredibly slow, but then again, this kiln will be electric, and will only use 1500 Watts. That’s nothing compared to a commercial electric kiln, but it is a build [Matt] designed himself without any outside help, using only parts he can easily acquire. In any event, this is an excellent project for the Hackaday Prize.
16 thoughts on “Hackaday Prize Entry: An Open Source Kiln”
That is so cool! For now, I will stick with sac-crete and a bucket.
Trouble is, kilns aren’t meant to be cool, they’re meant to get hot.
Now he just need to check these bricks for low Fe2O3 and high Al2O3. Otherwise to the 21kWh electricity bill will have to add the nicrome replacement cost and hassle every few uses at temperatures for firing clay.
Some practical heating wire info here:
[S] is correct the iron acts like a flux, this is why, generally speaking, the red clays are earthenware and fire at a a lower temperature. So far the project is mostly a howto for making bricks, there is no real kiln happening, however the diagram indicates that he is going about it the wrong way around, literally. You want to build a bell shaped structure in a steel frame that you can raise and lower with a overhead winch. This design holds heat much better. Also with the bricks try having a gradient in the blend so that the inner, hot, face is as high as possible in the lightweight material and there is more clay on the outer face where the greater structural strength is required.
Here we just use chamotte clay, sometimes mixed with cement. It’s common material here because many people use traditional furnaces for heating and some even for cooking. Besides, people used to make clay or brick kilns long before HaD prizes. like in bronze age, so [Matt] is doing nothing new or complex…
Very true and you only need that open top design if you are dealing with hot gases and can’t make a cross flow design.
This technology goes back to our very beginnings, and we will never do it with as much competence and efficiency as achieved thousands of years ago.
Watch; “How Beer Saved the World”.
That’s a bold claim.
I think modern ceramics, even just mundane ones, give the best artisans (pick a century) a run for their money. The exotic ones have potential to truly be the future for many things.
Slip casting is still in use and well understood today.
I disagree – spend a couple of hours watching the backbreaking day-long work of iron-age style smelting to produce a single implement, then compare:
Comparing a pottery kiln to forging metal?
Smelting Magnetite via Fine Straw, Termite Clay Limestone Deposits and Hardwood Charcoal. Damn Epic! Thank you for the fine vid link.
Don’t most clays and ceramics have a preferred heat profile? 14 hours with one 1500W (15A outlet in the US) element is a cool project but how useful is it? You’re not going to be turning out projects at any real frequency after you factor in cooling time.
Most places where you could make a living off of being the local potter are probably going to be better served by a gas or even charcoal fired kiln. A methane digester could supply gas in places where propane / natural gas aren’t practical; loads of places already use them for cooking.
This is an awful amount of effort to avoid spending $150 or so on fire bricks. I happen to have a small hobby kiln that is also around 1500w, with a steel enclosure and hinge-down front door, which I bought at Goodwill for $15 because they didn’t know what it was 20 years ago. Its interior is about half the size of the OP diagram but it gets to temperature in about 4.5 hours.
I was thinking the same. Doing it yourself is fun, but sometimes you just need to realize you get easier and probably better results if you just source some appropriate resources. Even with the right materials it is quite a project to get right and properly tuned.
This seems to strongly suggest that ‘any old dirt’ can be used to make refractory ceramics. The clay content varies a lot from place to place. This could be a total waste of time if you start with low clay soil/dirt. Why not just buy some clay from somebody who has already dug it up from a clay deposit? I’d rather avoid doing work for its own sake.
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