Instructables

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.

 
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Step 1: Assemble Your Supplies

Picture of 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

Picture of 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

Picture of Affix Can to Brackets

Use metal screws with a washer and nut and fasten securely.

Step 5: Attach the Pipe Fitting

Picture of Attach the Pipe Fitting

Just screw it in. It should all look like this.

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mist42nz2 months ago

what kind of temperature do you think you can get to?
I'd love to have something that could melt copper & brass for amulets.

GregC1 mist42nz1 month ago

no way in hell. built one to see for fun, useless. unless you just want to make some metal kinda hot and not really hot enough to forge anything bigger than a pencil.

EurekaFactory (author)  GregC11 month ago
Small can, small items; bigger can, bigger items. But "for fun" is what it's for. Probably need a more professional arrangement for melting copper and brass, but certainly worth tinkering with to try, I'd say. Really, though - it's just a tomato sauce can with a fireproof lining made of plaster of paris and sand, not a professional forge. It's a proof of concept experiment with some very rudimentary forging capability.
EurekaFactory (author)  mist42nz2 months ago

Hoping someone will have answers for the glass, copper and brass questions - We're curious, too! Just checked over in the Communities section, and in "Answers" and didn't see much on either of these topics, so definitely something worth exploring further.

I'm not sure about glass, but I have plenty of information on metals and their properties regarding casting and forging.

I have done casting, and I can tell you brass and copper both require high temperatures that this type of forge is not capable of achieving. You can melt aluminum and use it for amulets, but it sure won't look like brass or copper.

jscanlan mist42nz2 months ago

Try turning it on end and use a crucible I think that would work

I have made these before and they are a project doomed to futility. The lining will crumble in about 1 to 2 months if you use it with any excessive heat at all.Air pockets will form it after use (it cooks it, and the plaster of paris is actually what crumbles and overheats.)and the chemical composition just falls apart.

Appreciate the insight and experience. But we're not expecting sophisticated, or long term endurance from a spaghetti can forge. It's just a proof-of-concept, fun-to-tinker with project and we've learned a lot from it. It's obviously no substitute for a real forge nor is it intended to be. It's certainly been instructive though!
petawawa1 month ago
Would it work with a 19 0z can?
EurekaFactory (author)  petawawa1 month ago

Sure - but remember the smaller your can the smaller your furnace and the smaller work area you have.

DaveDoesThings made it!1 month ago

Works great! Tomorrow it's time to try a few mods to the interior shape, clean it up a bit, and make myself a spork!

(photo shows first burn, still not hot, was having issues with torch going out because of wind hitting the air holes, fixed, better/hotter now)

IMG_2071.JPG
EurekaFactory (author)  DaveDoesThings1 month ago

Awesome! Congrats!

jscanlan2 months ago

Would refractory mortar.be a better choise? I know plaster of paris and sand is cheap but a better quality material in the chamber might last longer and be easier to work.

it will work better, but it is quite costly. Having experience in casting and forging, I prefer Koawool, a flexible, high resistance insulation for furnaces.

ghost112 months ago
this will be a fun project to make. I've always wanted a forge but they are big and I just want one for fun.

Wow! Now your all set to be a ferrier for shetland ponies.

epicalien2 months ago
I love the tiny anvil
EurekaFactory (author)  epicalien2 months ago

I think we all do. What's not to love about a tiny anvil?! :-)

padbravo2 months ago

Glass?
someone could add info on that?

neffk padbravo2 months ago

Hot work is usually quite involved. I'd take a class on it, to try it out, without having to buy/make a lot of equipment.

eruger padbravo2 months ago

The only glass work that I am familiar with is neon tube-bending I did in art school, and watching the flame workers who make the little ornaments for tourists, but in both cases, a propane flame in the open was plenty hot enough, and anything more elaborate was used to heat a larger area more evenly. So this setup might be perfect if you want long graceful bends, and I think it may be good for blowing small bottles or such. For the very important annealing process that others mention here however, what you need is a kiln that starts out below the temperature where the glass starts to glow and then cools down slowly to room temp, usually overnight. That's usually done with electronic controls or some poor apprentice loosing sleep. People have also accomplished this with an oven and a fire that slowly cools as it burns through its fuel. Without annealing, glass that has been fine for months can practically explode if it's lightly tapped the wrong way.

padbravo eruger2 months ago

hahah! that is a good one! the "poor aprentice"! medieval times?

eruger padbravo2 months ago

You would be amazed at how primitive a lot of glass and metal crafts
still are, even in highly industrialized places! They are also some of
the last bastions of medieval-style apprenticeship! Like a bronze
foundry, where a 1st century roman craftsman would only need a day or
two to catch up with the improvements, and the new guy is still often
unpaid, or may even be paying for the privilege of learning on the job.

I'd say it's possible to get it hot enough for small rod glass, BUT..... You might need a similar annealing oven to slowly harden the object afterwards.. I've melted beer-bottle glass with a propane torch, but it usually shatters if allowed to cool too quickly.

Ah, I get it... if it gets cooled too quickly, it will fragment or something else...
Tks for the info...

They tend to fracture, as if when you put hot water into a cold glass, the inside will remain expanded, but the outside will cool in normal air temp.. and when the cooler outside shrinks, *CRACK!*.. and it tends to go continue right into the inner material. The beer-bottle example, if removed from the fire, and not allowing the fire to die-out around it, the glass will fracture, and split the entire point.. result, broken pieces. (this is why so many suggest using a camp fire, where it'll burn out slowly, but the coals will keep it warm, until they eventually burn out.)

Tks!

Hi! Glass needs to cool down very slowly, drinking glasses are kept in an oven for a full day after forming them. You might want some other form of oven to keep your glass-thingies really warm - maybe a potter's oven you can move into your workshop?

Tks for your answer... I did not know that fact about the "normal" glass on a regular kitchen glass... probably you work on that kind of industry?

Anyway... seems to be that this kind of workmanship uses a lot more patience that I have...

I a more on metalworking, and i wold like to star with molding and molten metal... maybe using this design as basis for a small furnace...
spark master2 months ago

Hi Neffk,

Could he use fire clay sold in Ace hardware etc? Unless you can find Castable refractory (here on LI it is not easily found).

I had to go to a masonry place to get it and it was a 50# bag. But for a tiny project like this, I think you could get it in small amounts... yep, amazon has something:

http://www.amazon.com/Castable-Refractory-Rocket-S...

Alternatively, you could buy/reclaim some fire brick. It'd be bigger, harder to make the frame for the bricks, and you'd have to drill a hole in one of them... it's kind of beyond the scope of your project. There's always the impulse to make things bigger and better, which sort of defeats the purpose of this cheap, quick, and safe forge, right?

tnetcenter neffk2 months ago

Try using a kiln brick. I recently saw a mini-forge created by drilling a chamber into a kiln brick, then drilling a hole for the torch nozzle. Use a dust mask when drilling the brick, kiln bricks use a silica material that would be real bad to breathe. You could be operational in a 1/2 hour or less.

Also, check YouTube - there are several videos on how to make slightly larger forges using coffee cans and so on. You can also use refractory wool (kinda like wall insulation - BUT not!) to line a small forge.

itwilliams332 months ago
Hi, I'm trying to create my own little black smithing shop/area. I have already obtained a forge but where did you get that conveniently small anvil?

That looks like an old farrier's anvil, for shooing horses and other light repairs around the farm do a search for 2lb anvil and should find something similar. Note: if it's a cast iron anvil, it's no good for working iron. Steel ones aren't as common or cheap though.

EurekaFactory (author)  itwilliams332 months ago

It's adorable, isn't it? It's also ancient. Been in the family a really long time and I have no idea where it came from. Did a little casual research out of curiosity and found that Tandy Leather sells 2 lb anvils for $16 - which is probably what ours was originally used for.

eruger2 months ago

As a sculptor, I would recommend against using the torch to dry the plaster mix. I would do nearly the opposite instead: using the cardboard tube inner roll and paper fitting plug, as the authors suggest they should have plus a cardboard or tin cover on the bottom, mix your sandy plaster a bit wetter than they suggest, just dry enough to keep the sand from settling. Slump it into the can and tap or vibrate the side to clear any bubbles. Once it starts to cool off, immerse the whole thing in water overnight. The heat produced by the plaster is from the chemical reaction which hardens it, and which consumes water. Soaking it will ensure that it has enough water to fully cure.

EurekaFactory (author)  eruger2 months ago

Hey this is great info, thank you!

baecker032 months ago

another idea... use a larger object such as a paint can and a smaller can to fit on the inside. use wire and the same cementing mixture or another to make a slightly larger forge. the current apparatus seems like it is just too small for any practical work, especially with glass. what you would end up doing, is fit the can into the paint can and somehow affix (drill holes and use wire + nails?) the can so that it is suspended within. I am suggesting using a method similar to how hanging ceilings are attached. after this step, pour the cementing mixture into the space created by the two cans and cure. somehow create an opening that is somewhat smaller than the paint can lid, as you want minimal heat loss. this way, you will have a forge that will hold slightly more material and will have reserve heat. the opening should ideally be near the bottom so that heat loss is minimized.

EurekaFactory (author)  baecker032 months ago

This is a cool idea! Got us back to thinking about the cardboard tube/insert idea, that would burn off on the first burn, leaving a space. We agree about making a smaller opening cover that would minimize heat loss, too.

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