Introduction: Coffee Can Forge

Picture of Coffee Can Forge

I know that this isn't an original idea, but it is something I have wanted to do for a long time. Given I don't really have the space for a real forge I thought this would be a good place to start some metal-crafting.

Things you will need:

Coffee can (I used a small one)

Couple of bolts, washers and nuts too.

Drill and bit to make hole the size of your bolts (also a step bit to make the hole for the torch.)

Scrap piece of metal for base

Plaster of Paris

Sand ( I cannot stress enough the importance of sand)

*I am going to assume that all of you on this site are competent human beings and do not need to be reminded to wear your PPE (Personal Protective Equipment) i.e. safety glasses and such. Then again we should never underestimate the power of the idiot to slip in here and do something foolish. So......... Wear the proper safety equipment and use your tools safely. PSA over.

Step 1: Attaching Coffee Can to Base

Picture of Attaching Coffee Can to Base

You will need a base to keep your coffee can upright while heating. Find a piece of scrap that is big enough to support the can plus 5 pounds. I recommend some channel or square tubing.

Decide where you want your holes on the coffee can and mark that distance on your base. Drill the holes to accommodate the bolts you will be using. I used 1/4" no need to go nuts here.

Once the holes are drilled, attach the can to the base with the bolt heads inside the can. I used lock washers, because I didn't want to have to worry about the bolts coming out of the base and making a hot melty mess.

Step 2: Adding the Torch Port

Picture of Adding the Torch Port

I used a 1/2" pipe for the torch port.

To accommodate the 1/2" pipe I used a step bit to drill through the coffee can.

Just thread the pipe in and mark where you will need to cut it off. I only left about a 1/2" inside the can and 1/4" outside.

Now the hard part is over.

Step 3: Plaster the Inner Walls.

Picture of Plaster the Inner Walls.

To plaster the inner walls I used a ratio of 1/2 Plaster and 1/2 sand with just enough water to get a good mixture (about the consistency of play-doh.) Line the bottom and inner walls with about 1/2" of mixture. Try to smooth it out as much as possible. Clear the torch port of any plaster debris and you are done.

If you got the mixture right, there is no need to wait. You can insert the propane (I used MAP) into the torch port and heat away. It will take a while for the plaster to cure, but when it does it will get red hot.

Remember to use heat protection when using this thing it is small but very functional. Also the can will still get hot. I am thinking of adding some fiber insulation around it. Good luck and be safe!

Comments

Joe_M (author)2015-02-08

I would like to see it in action, and what you make with it. I wonder how big it can be and still use the map gas torch. I also wonder if there is a cheaper way to heat it, as map gas can be expensive , depending on how long it takes to complete a a singe job. Please post your first project so I can see it in operation. Thanks for sharing.

Lithim. (author)Joe_M2016-12-05

i upsized the design to a 10 litre steel bucket and it works great! Of course i ditched map gas and made it a bintōchan (japanese charcoal) heated forge

janetty16 (author)Joe_M2015-02-14

Joe,

You asked and I have delivered!

https://www.instructables.com/id/Tempering-a-knife-...

You can also see the modification I made to the front of the forge.

brentreissman (author)2015-02-08

DO NOT USE A GALVANIZED STEEL CAN. These can cause poisoning if not insulated well. Also i recommend spending the extra money to get refractory cement.

Lithim. (author)brentreissman2016-12-05

i upsized the heck out of this design and used a 10L galvanised steel bucket and ive never caught metal fume fever, i just use alot more of the sand plaster stuff for insulation (i only need a small area because i use it as a blacksmiths forge, and this basically just holds burning bintōchan)

janharm (author)brentreissman2015-02-25

..Why not? I can't see much harm in that, since it is a very, very tiny bit of Zinc- which is not a very poisonous metal at all.

brentreissman (author)janharm2015-02-25

because its not just zinc. I use zinc for casting and its not bad, but if galvanized steel becomes too hot gaseous zinc oxide can come off and THAT can cause zinc poisoning. Please look up zinc oxide poisoning. I don't want to see anyone get sick (you'll recover, but it sucks)

Ravenstine (author)brentreissman2015-05-30

I also could be wrong but I believe that coffee cans are tin-plated and not galvanized. I say this because I've used plenty of steel cans to make forges and have never had zinc fumes from them. I have, on the other hand, had zinc fumes from pipe nipple. Even if it were galvanized, it's such a small amount that you'd have to be in an enclosed space(which is stupid) in order to breathe in enough for it to be a problem.

Ravenstine (author)brentreissman2015-05-30

Just pre-burn off the zinc plating before serious use. The dangers of zinc poisoning from this sort of thing are vastly over-stated anyway; fume fever also isn't permanent. Very elementary precautions(ventilation, mask, etc) prevent this sort of thing anyway.

JacobA5 (author)2015-02-10

I'm just spitballin' here, but what about cutting out a "window" in the bottom of the can and adding a swing door on it so you could make larger pieces? Also, if you can add threaded insert where the torch attaches, I imagine it would be just as easy to connect a hose for the liquigas of your choice. Very cool concept jannetty16!

janetty16 (author)JacobA52015-02-10

Do whatever you want to make it yours. that is why i keep coming back here. sometimes someone's design is just the spur i need to make s project sit my specific situation. just don't stop crafting.

tyeargin (author)janetty162015-11-26

my thoughts also

ToggleSwitch (author)JacobA52015-06-03

Although this could be a great idea making a "window" could let a lot of the heat out but if your need is heating longer pieces then maybe you could try connecting two cans for the forge

johnnybravoesq (author)2015-08-11

How large a can will this work with using a standard propane/butane mix torch?

janetty16 (author)johnnybravoesq2015-08-12

I'm not sure
I had to enclose the end somewhat to get the temperature up to a desired level

SparkySolar (author)2015-02-18

Wicked cool

jpretorius (author)2015-02-13

intrested

throbscottle (author)2015-02-08

Would this be any good for melting aluminium for making little castings?

janetty16 (author)throbscottle2015-02-09

I don't see why not. I think aluminum melts around 600 C I haven't measured how got this gets.i simply use it to harden temper knives I have made.

amberrayh (author)2015-02-05

Be safe is right! Have you seen this video?

https://www.youtube.com/watch?v=A796N_YZTm8

Wear a face shield, gloves, apron, whatever you can get your hands on... that being said. Great 'ible! I hope we see many more from you in the future!

janetty16 (author)amberrayh2015-02-05

I have now! Wow. They are so lucky they didn't get seriously hurt. I cant imagine what molten metal on the skin would feel like. Yikes!

smc wall (author)janetty162015-02-09

When molten metal hit me, I didn't feel anything because I was in shock, then a few seconds later, the pain came

wb7ptr (author)2015-02-09

I can see a lot of uses for this thing, but the PSA is definitely called for. A lot of idiots out there. Also, be careful about fire hazards and using it around flammable or explosive substances. It's supposed to be a functional useful forge, not a bomb!

granthams (author)2015-02-08

Are you mixing your sand/plaster by weight or volume? Castable refractory isn't that expensive and is available from home centers, fireplace installers, etc. On my furnaces Alsey hi-cast has served me well and doesn't break down quickly like home brew mixes.

janetty16 (author)granthams2015-02-08

Volume. Good tip on the refractory cement. However, I think of mine as a somewhat disposable model. It really is no trouble to make (I made mine in less than an hour) or knock out the plaster and reapply (this step took less than five minutes).

trknust (author)2015-02-08

What you need to go outside of this is Kaowool. This is very similar to fiberglass insulation only it is made out of ceramic instead of glass. It is what we use inside the forges we use for blacksmithing, and knifemaking.

janetty16 (author)trknust2015-02-08

Thanks for the top. I'm not to keen on fiber glass. I'll check it out.

redmarkonthewall (author)2015-02-06

To increase the maximum temperature our forge could obtain I would've fashioned the plaster mix in such a way that the opening was around half the size.. Also consider making a cover for the opening to really help intensify the heat. Otherwise a pretty good forge.

That's a great idea and I've already done it. I noticed when I was heating up a knife that I couldn't get the knife to lose its magnetism even with map gas. So fashioned a small steel plate and plastered it on the end with about a 2 inch hole in the middle. Now I think map gas might be a bit too much. The can gets very hot using this method and really needs to be insulated. I may post some pictures of my modifications later.

Krienert (author)janetty162015-02-08

You also might consider purchasing fiberglass matt (the loose weave commonly available at auto part stores) and chopping it into small bits with gloves and a sharp utility knife. Then mix this into the sand plaster mix. It will greatly reduce fracturing!

SallyG1 (author)2015-02-07

awesome little bitty forge! I want one!

vonronge (author)2015-02-07

Nice! Expensive to heat by volume but for small projects this is great!

coledotson0548 made it! (author)2015-02-06

I made a coffee can forge but I needed a longer cylinder. I joined two cans and added a few more inches of plaster/sand mixture to concentrate more heat and insulate a bit more. But like you said, the can still gets a little warm! lol

eugenekaub (author)2015-02-05

Excellent line. Never underestimate the power of an idiot.

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