DIY Blast Furnace on a Budget!




Introduction: DIY Blast Furnace on a Budget!

this is for a blast furnace, they can get really hot and melt metal, so they need firebrick, firebrick is expensive, about $4 each! so we made this for under 100 dollars and it works. this idea was needed because we needed something for melting metals in our forge (sorry, no instructable for that) and this one requires charcoal on bottom, and coal on top to get the best heat possible, shoutout to The King Of Random, they inspired this low budget project.

Step 1: Items for Making This

plaster of Paris 5 containers

play sand 60lbs

Menards bucket 3.5gal


55-gallon drum (or even a metal bucket)

handheld blower for air

1 in NOT STAINLESS STEEL metal pipe nipple (12in)

a screw thread to PVC adapter

1 in hole saw

a drain hose coupler 1in

crucible, or a fire extinguisher (use a recalled or empty one, NOT A NEW ONE or you waste money)

2 u bolts

sheer determination, (some was difficult)

Step 2: The Main Housing

so, the first step is we took the bucket and cut it 14 inches from the bottom with an angle grinder. and then sand the edge to not harm yourself by touching it! it will be sharp.

Step 3: Brick Mix

we will now be building the main chamber, where metal melts, the brick mix is here

3 buckets plaster of Paris

3 buckets sand

2 buckets water (any is fine)

and pour into cut drum


Step 4: Forming the Cavity

we are now forming the area will the heat will be contained to

we are now using this bucket and setting it in the mix to make the cavity, this bucket will get destroyed, but fill it with water to hold it into the mix,

let settle for 24 hours and harden

Step 5: Blower Assembly

this blower uses a vacuum to push air into the chamber and supercharge it, it is a handheld one with a bag on it, we remove the bag and it works great until we test with this entire assembly, it sounds like an AIR RAID SIREN (possible future project) because of the ripples in it, so that was an issue, we fixed it by partially blocking the airway and it stopped, but we could not get enough air in, so we made modifications, no tube at all, just blower to the coupler to the screw fitting to the burner, the burner is the metal nipple, do not get stainless steel, when it gets hot, it releases poisonous fumes, so be aware!

Step 6: Inner Chamber

Once it has officially been 24 hours, the bucket is ready to be removed, when removed ours, it had a problem, there was an air pocket in it! we fixed it by filling it in with a touch of brick mix from the lid mix, so it was all good, let it now sit out for another 24 hours to fully cure

Step 7: The Lid

we used the rest of the plaster and some more sand and water mix, just make it with 2 buckets of plaster instead, so we made it by taking a 5-gallon bucket, measuring up about 9 inches, you know the drill with the angle grinder and now we have a custom bigmouth bucket, you pour in the mix ingredients and mix with your hands until all globs are gone, then take your bad fire extinguisher and wrap it in press and seal or dish sealer and put it in the mix dead center, place your u bolts beside it and in between the side and the extinguisher and get the bottom bar buried, it will serve as an anchor, then let it sit for 24 hours, remove the fire extinguisher (when removing it we almost unscrewed it as it was pressurized !!! be careful) by twisting it out of place and then clean up the hole and let it be for another 24 hours to cure.

Step 8: Burner Hole

we took that hole saw and put it in the side and drilled, be careful as it can jump and break bits off, and after that, we inserted the nipple to hold the hole open in case it wasn't fully cured in the center! and supported it by the empty bucket the plaster arrived in!

Step 9: Full System Test!!!

we loaded it up with charcoal, connected the original burner assembly and turned it on, and lit it. it did not get enough air so we modified it to get more air and NOT sound like an air raid siren, and there is no tube just a blower to the coupler to screw the adapter to the burner. and it got nice and hot quickly! so it was a process, just be careful with this, it does have the ability to destroy and kill!!

Step 10: Admire Your Work and Take Photos

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    Reply 4 weeks ago

    yes. i am showing this to promote what I did, I will be converting it to propane because of effieincicy


    6 weeks ago

    Sounds like a cool and neat Idea for people who want a forge.


    Reply 6 weeks ago

    yes, we have a forge, a forge is a area to heat metal and pound it into shape,a blast furnace melts it to pour into molds, you can use a old muffin tray to make ingots


    Question 6 weeks ago on Step 5

    Also don't use galvanized steel, Zinc fumes are really bad, gives you flu like symptoms and can kill if higher concentrations.
    The plus side of galvanized is you can soak the parts in vinegar or other acidic solution to clean the zinc off.


    Answer 6 weeks ago

    yes, or use it outside while wearing your PPE, leather apron, gloves, mask/respertir/saftey glasses

    uncle reamus
    uncle reamus

    6 weeks ago

    Plaster of paris IS NOT a refractory. It is in fact a heat sink. It is actually robbing your heat. POP starts degrading at around 450* F, you need temps much high than that to melt metal. At best the POP will degrade quite quickly at worst it can spall, blowing out pieces of POP along with the charcoal inside.
    Please if you are going to melt metal do it safely and get the materials that are made for doing such. Just becuase someone on youtube does it, does not mean it is safe. Melting metals is no joke and should not be taken lightly. A slight slip up could lead to a long hospital visit or a trip to the morgue.


    Reply 6 weeks ago

    hello, we got the furnace to about 1,041 degrees, and it worked just fine, make the mix, pour it into a cake pan, and hold a blowtorch to it, and shoot a video. it will not allow lots of heat to escape, it worked well, we mixed lots of small air pockets, it is like reactory then, we also melt lead, it is dangerous but it is efficient.