Waste-Oil Forge and Foundry




This demonstrates how I made a basic setup for casting, and can also to some extent be used for blacksmithing.

Let me state a disclamer that I know almost nothing about blacksmithing and most of my knowledge thus far is from research and not experience. The processes and materials presented and resulting from the information I am sharing are potentialy lethal. Please consider this as a primer to get you interested and demonstrate how simple it is to make the necessairy items for forging and casting. Do, however, search elsewhere for more information before undertaking any projects.

some good places to start:

other instructables:



Step 1: Waste Oil Burner

For the burner you need 1 and 1/4 inch pipe fittings: two T's, two full-thread nipples, one 3" long nipple, two caps, a reducer that goes down to 3/4" and a 3 inch long 3/4" nipple.
Fit everything together as shown with a couple pipe wrenches except the top cap. Drill a hole for the oil line. Test it to make sure it's working the way you want it to. Then encase it in fire clay. (see next step)

For the oil line I've just used some 1/4 brass tubing I had but steel brake line would be better. I fitted this to a valve and the valve to a tube going to my oil container. So far my container is just a can with a copper coupling for a hose in the bottom.
For the forced air I took a small vaccuum and duct-taped a tube to the air exhaust, the tube is about 20" long. Then I use a pipe clamp to secure it to the burner. Eventually this will be replaced by a small squirrel-cage type blower.

To run the burner I first start a wood or sometimes charcoal fire in it. Just get some small chunks of wood and fill up the main section of the burner. Once it's burning well put the cap on and connect the blower, turn it on as low as you can. Turn the oil on to a very slow drip, it'll probablly get really smokey for a bit. If the flames go out back down the air input or throw in a couple more peices of wood. As the burner heats up try turning the blower on higher, work gradually until there is a steady bright yellow flame comming out of the blower. As the air is turned up you'll have to open the oil valve more. On a full blow oil will have to be streamed in steadily and excess will fill the bottom and leak out the air input. Just catch this with a cup and pour it back into the oil container.

Step 2: Furnace

The Furnace is really simple.

The bulk of this is fire clay. Other than that you just need something to contain it in and another can to leave space for the heating chamber.
I started out small with a coffee can and then went to a larger one made in a big popcorn tin.

Next you need fire clay. I don't live anywhere near a foundry or within an easy distance to get fire clay so I made my own. for this you need four things; portland cement, perlite, silica sand, and bentonite.
Just about any lumberyard or hardware store carys portland cement. Don't confuse this with ready-mix or even masonry, get the stuff that says PORTLAND CEMENT really big on the outside of the package.
Perlite is the white stuff in potting soil. It comes in a bag by itself, it can usually be found at walmart but can also be found at nurserys, lawn&garden places and hardware stores.
Pure silica sand is best but any fine sand will do. probablly the easiest to get is the bags of "play sand" you can find at walmart or building centers like home depot or lowes. A lot of tractor supply stores in the midwest carry it during the summer. If you can't find it or just don't want to pay for sand you could just get some from a dry riverbed and sift it (don't take sand from beaches).
Bentonite is what most cheap cat litter is made of. Just look at the label, it should say ingredients: bentonite, make sure it's not mixed with other things like fragrance. If you get cat litter you'll probablly have to find a way to grind and sift it. This takes a lot of time and effort. If you don't want to go through all the trouble just find somewhere online to buy it.

To make the masonry I go with a 1:1:1:1 ratio.

mix one part sand, bentonite, and perlite together, add a little water and mix throughly.
let it sit for 30 minutes.
add a little more water and mix again, let sit for 45 minutes.
add one part portland cement and enough water so everything is moist and sticks together, but not too much so it's runny. You want it just wet enough to cake easily in your hand and not crumble when you squeeze it.

First fill the bottom to the thinkness you want and pack it down. Then put the center can in and ram fire clay down around it. Once the clay dries a hole is drilled through the wall just above the bottom of the heating chamber and to one side so the heat from the burner tends to spin in the chamber. Then a lid will need to be made. Just use another tin about the same size in diameter, though it only needs to be about 3 inches thick and leave a 2 or 3 inch hole in the center. Once it is set remove the lid from the tin.

Step 3: Flask and Casting Bench

The casting bench is really just a box with legs that brings it up to a convient working height. On the inside of the box 2 or 3 inches from the top make horizontal cleats on the front and back. Cut two peices of wood to fit across these. The next thing needed is two boards big enough to cover the flask.
The flask itself is simpler than people make it out to be. Just make a box without a top or bottom and cut it in half. Then use some thin material to make an alighment peice on two sides of the flask. If you consistantly have problems with the sand falling out, attach a small strip of wood around the edges of the cope and drag where they meet.
Most home setups use greensand to cast in. This can be ordered or easily made without much expense by mixing sand and bentonite. An 11 to 1 mix of sand and benotnite, respectfully, (or approximately 8% bentonite) is suggested.

Step 4: Blacksmithing

I don't have a proper anvil, they're expensive. But I do have a peice of railroad that works pretty ok with small projects and a couple large chunks of steel. One is bolted to my workbench and the other I attach to a stump when working outside.

For work other than casting I made a rectangular furnace, using sheetmetal to form it and then filling it with fire clay. Both ends are open, which makes heating specific parts of long peices easier.

I made some really ugly, but simple, tongs by riveting two peices of flat bar together then heating the end and twisting it.

I got a small sledge hammer because somebody threw it out when the handle broke. I just made a new one, free tools.

There were some big timbers on public land I found while out for a hike. They had been through a fire (conviently annealed) and I salvaged some of the steel fittings off of them.

When you're creative about materials things get cheaper.

Step 5: Casting

I'm still working on this. When I get a process down that works I'll post it.

here are the fundamentals..

How to set up the flask:
The sand should be moist enough to squeeze in your hand and retain it's shape, bounce it in your hand and it shouldn't crumble.
place the bottom (or drag) upside-down on one of the boards, put the item to be cast in the middle of the drag and fill it up with sand. Sift sand that will go immediatly around the pattern and don't worry so much about the rest. Use a rammer, or I've found that a small rubber mallet will work in a pinch, and pack sand tightly around the pattern. It takes a while to get a feel for how much pressure to use, but eventually you'll get the hang of it. Once the drag's compacted scrape off any sand that sicks up over the top edge. Place the other board on top of the drag and with both hands holding it securly flip it over. remove the top board and dust on parting powder. I've read that coal dust works great but it's a lot easier for me to get talcum powder (baby powder, talcum or corn starch can be used) Then put the cope (or top) in place. Pack sand onto the pattern just as you did for the drag. Then cut vent holes above the pattern by pushing a wire, anything from a coat hanger to a knitting needle will do, down through the sand until it touches the pattern. Next cut the sprue, or pouring hole, with a peice of thin brass or steel tubing about 3/4 of an inch in diameter. Now lift the cope off of the drag and set it on it's side, you'll know right here if you've done a good enough job ramming the sand. Once the two are seperated cut the gate, or runner, from the sprue to the patter. A simple tool to use is a spoon, making the channel about 3/4 of an inch wide and about 1/4 of an inch deep. Carefully lift the pattern out of the drag and then place the cope back into position. Pour the metal in a small stream and to one side of the sprue to let air escape and so it doesn't hit the bottom hard enough to loosen the sand. Give your casting time to cool off, then seperate the flask and take out your new part. Cut off the excess from the vent holes and sprue and stick them in a bucket for future use. Sand down your casting and you're good to go.



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    47 Discussions

    the first couple runs were with oil I'd changed out of my truck, after that I just got some from a local recycling center. I'd suggest going to an auto shop though, the recycling center dumped all sorts of stuff into their waste oil tank.

    infinitely better, it burns hotter and cleaner. The idea of a waste-oil burner is that it uses something that otherwise would be waste and costs virtually nothing to operate. If you don't mind paying for all of your fuel though, I'd suggest propane.


    Reply 1 year ago

    Probably not. The burner is made of steel and its not melting so no


    its best to use vegetable oil over motor oil because motor oil burns to give off toxic chemicals and this can be absorbed by your metal and change its composition and properties and not to mention the health risks


    Reply 9 years ago on Introduction

     Anybody who would inhale the fumes from burning oil should not be allowed to handle sharp tools or have matches or a lighter.


    Question 1 year ago

    Can you post a diagram of the burner? Your explaining was sort of vague


    8 years ago on Step 2

    I'm making a furnace of a different design but with the same mixture for the refactory. So, I sat around with some friends and pounded out a gallon of cat litter, that was fun. But the perlite I have comes in small pellets, should i grind those up as well, or will they dissolve in the water?

    3 replies

    Reply 3 years ago

    do not use this refractory.
    fire clay is a clay, not a mixture.
    dont use portland cement, foundrys get hot and portland justcrumbles away at high temperatures and might explode.
    use pure fireclay and mix it with styrofoam beads 1-3, this will insulate, coat this layer with furnace cement and fire clay 1-2, this should be fine.
    visit alloyavenue.com for a helpful community.


    6 years ago on Introduction

    I'm not quite clear on how the oil burner works. seems like the oil just drips into the tee's. Does it burn there, or is it blown into the furnace and ignited there? or what?

    1 reply

    7 years ago on Introduction

    I'm interested in making this but have an important safety question:

    How can you unsure the fire doesn't ever run backwards up the oil line to the oil can?

    Ex, what if the line gets clogged? Would the flame move backwards?

    Or, what if you use up the last of your fuel, leaving the oil line coated in oil and filled with air? Why wouldn't combustion continue up the oil line into the tank, causing a potential disaster?

    Thanks for your help.

    1 reply

    The short answer it that it requires so much energy to effectively burn waste oil that you're never going to get an instance of blowback, the line outside the combustion chamber simply should never get hot enough to ignite the oil within it. That said, of course it is within the realm of possibilities as it is gravity fed which allows the passage of air if the oil container should run dry. There are measures you can take to prevent potential disaster however. The most obvious is simply never set up your operation within 20 feet of anything you wouldn't mind catching on fire. secondly use a small container to feed your burner so that, should this unlikely even occur, you need only to cover the container and stop your air supply to extinguish any flames. Thirdly, regulate the flow of oil with a valve. should you be so absent minded that your line runs dry you need only to close the valve closest to the combustion chamber to prevent any hot gasses traveling up the line.

    If you do not have the attention span to prevent your oil reservoir from running completely empty, you're probably not qualified to to attempt anything for which a furnace is required in the first place. Do the world a favor and find another hobby.