Introduction: Itty Bitty Mini Forge
Long time fans of blacksmithing, we delighted in having the Florida Artist Blacksmiths Association demo at our recent Gulf Coast MakerCon event in March. We were equally delighted to find a way to bring a little bit of the blacksmith arts into our suburban garage, when we came across this great video by NightHawkinLight, on how to make a Soup Can Forge. Intrigued, we looked around for some written step-by-step instructions and didn't see any, so we hope NightHawkinLight takes it as a compliment that we documented our little build and share it here, as perhaps a companion piece to his terrific how-to video, which we've included here and highly recommend you watch in its entirety first.
Our build time, start to finish: about an hour and a half, mostly 'cause we were klutzy with the fireproof lining mixture.
Step 1: Assemble Your Supplies
You'll need:
- A can - we used a 28 ounce crushed tomato can, sans the crushed tomatoes. We chose to leave the label on for a Warhol-esque effect.
- A block of wood
- A black iron pipe nipple - 1/2" x 2"
- Two L brackets
- A pair of wood screws to afix the brackets to the block of wood
- A pair of small metal screws with washers and nuts to afix the can to the L brackets
- A small bag of sand
- A box of plaster of Paris
- A gallon ziplock bag to mix the sand and plaster
- A standard propane torch with a spiral flame nozzle
- Some water
- Safety glasses
- Fire Extinguisher - just in case
Step 2: Prepare Can
Drill two holes, about a half inch in from either end of the can.
On the opposite side of the holes, about an inch from the back of the can, drill a 1/2 inch hole for the black iron pipe nipple, at a slightly downward angle.
Step 3: Fasten L Brackets to Wood Block
Measure out your brackets against the length of your can and where you drilled your bracket holes in the can.
Step 4: Affix Can to Brackets
Use metal screws with a washer and nut and fasten securely.
Step 5: Attach the Pipe Fitting
Just screw it in. It should all look like this.
badideasrus added useful tips in the comments, shared here:
"i like this. it's simple and easy. a note though! most of what i read indicates that the angle the pipe enters the forge is important. you want to aim the flow so that it lines up with the circular cross section, so that you get a spinning flow of fire. (bleh, so much harder to say with words what a picture would explain in seconds...)
"make the pipe tangent with the inner chamber, so that it flows round and round, instead of straight into. this keeps fuel inside longer, and supposedly makes the forge burn hotter (i think it keeps heat in too) http://www.habairon.org/images/propaneforge.jpg (this shows basically what i'm trying to say XP)"
Thank you badideasrus!
Step 6: Make & Pack Your Fireproof Lining
Mix equal part sand and plaster of Paris in a gallon Ziplock bag, with enough water to make a moist clay consistency. It's a little too crumbly in this photo, and not quite enough. This was actually the hardest part for us.
We used a 12 oz plastic cup for measuring and based on that would recommend 3 cups each of sand and plaster, and about 1- 1.5 cups of water.
You have to work pretty quickly because the stuff starts to set up fairly fast, and starts getting crumbly.
Pack the mixture in firmly, until the can is about 3/4 full, then dig out a 1.5 inch diameter cavity (we used a plastic spoon), leaving about 3/4" plaster/sand lining the can.* Carve a wider hollow towards the back (bottom) of the can, to create a better heat retention area.
Run a tool, or the back of your plastic spoon through the iron pipe nipple to clear out the plaster there. Wipe the outside of the whole thing clean with a wet paper towel, and then let it sit for a half hour.
*Alternatively (it occurred to us later), you can probably stuff the nipple with paper, and insert a toilet paper tube into the center of the can, or something similar, and pack the plaster in around that, then either remove it or let it burn when you turn on the torch.
Step 7: Fire It Up and Dry 'er Out!
Insert the propane torch nozzle into the pipe nipple and light 'er up! If the air holes on the nozzle are near the tip of the nozzle, make sure they're not covered. Your itty bitty forge will burn cold for about 10 min. or so, until the last of the moisture in the fireproof lining is burned off, and then you'll start seeing the classic red glow of a nice hot forge.
Step 8: Forge Away!
Now you can start doing some small scale metalsmithing and glass forging.
And those are whole new how-tos! We have some ideas and hope to share some of those back here soon.
Have fun! And thank you NightHawkinLight for getting us started!

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86 Comments
8 years ago
I ended up building one for my brother as a Christmas present. I accidentally put the nipple on the opposite side as instructed, but I hope it won't affect function. Even if it sits on the shelf, it looks pretty cool. I think I'll show him your knife instructable and he'll probably have a go at it.
Happy Holidays! Thanks for the gift idea.
Reply 8 years ago on Introduction
This is fantastic to hear! So glad you made one as a gift. :-) It shouldn't matter on the nipple placement, as long as it's still positioned in the back. I don't have a knife Instructable, but NightHawInLight does here: https://www.instructables.com/id/How-to-Make-a-Soup-Can-Forge/ Have fun, and thanks for sharing back your build! Happy Holidays!
7 years ago
I can't wait to try this. Thanks for the awesome ible.
8 years ago on Introduction
i will be making mine with a steel fire extinguisher tube that i cut in half how long should the can be to make it into a forge?
8 years ago on Introduction
Lots of folks have asked about "crucible" type versions of this build. Check out this new Beer Keg Metal Melting Furnace. It might be just the thing!
Reply 8 years ago on Introduction
You are too kind... The soup can forge is perfection. Simplicity and elegant design...
8 years ago
Will this work with a webbed flame?
Reply 8 years ago
Not sure. We use a basic old propane torch. Maybe with a bigger can?
Reply 8 years ago
Ok thanks I'll try it out and tell you how it goes
Reply 8 years ago on Introduction
Keep us posted! Thanks for Making it Forward! :-)
9 years ago
I will definitely look into it. I'm just starting the craft, and planned on making the old "railroad track" alternative. But assuming I can find the baby anvil, I'll likely, go for that. Thanks for the quick response!
Reply 9 years ago on Introduction
Tandy Leather has them... but you can probably find one cheaper with a bit of research. I use the head of a sledgehammer. I had a friend polish and smooth a side at his shop.
Reply 8 years ago on Introduction
http://t.harborfreight.com/catalogsearch/result?q=...
15lb is the one i use
8 years ago on Introduction
Can this be done by removing the block of wood and L-straps altogether? By say having it standing up straight for a crucible type setup? Or would it affect the heat distribution/propane tank
Reply 8 years ago on Introduction
Hi Zach - there was some discussion in the comments about trying this and I saw that someone gave it a shot but I don't know the results. In searching on "Crucible" I found some similar ideas: https://www.instructables.com/howto/crucible/ but I think you're right to suspect the effectiveness of the propane heating distribution system with the current set up. I'd be curious to hear if anyone's had any luck repurposing the mini-forge into a crucible.
8 years ago
If i were to buy a graphite crucible what size would i use in this setup? I plan on building two, one up right, for making ingots and melting/pouring into molds and one for forging like yours.
8 years ago on Introduction
I love it. Great job in the forge and the Instructable. I made one nearly identical to yours before I saw this.
I used a new empty latex paint can and a few pieces of fire proof ceramic blanket for the container. For the heat, I used a torch nozzle like yours. Only I attached it by a hose to a big white propane tank from the BBQ grill.
I got a little fariers anvil and set it up just like yours.
Awesome job.
Reply 8 years ago on Introduction
That's a great idea! How's it been working?
9 years ago on Introduction
How long does the propane last for powering this forge?
9 years ago
Thank you, @Amercian Ruin I'll look into it. The sledgehammer is very clever