Introduction: Mini-Forge

A mini-forge is a fantastic tool to have around the shop. The mini-forge will allow you to make everything from jewelry to small pocket knives. It is an indispensable item for any shop where metal working will happen from time to time.

Bonus: Although not shown in this Instructable, this mini forge can be tilted on it's back and used to completely melt metals such as bronze and aluminum for molding purposes by adding a hardened steel kettle in the center.

Step 1: Watch the Video

Before you move on to the next steps, take a minute to watch our instructional video on making the mini-forge. This video has some neat tips and tricks that will make this Instructable easier to follow.

Step 2: Acquire the Components

You're going to need several items to complete this mini-forge. All of them can be obtained at your local big box home improvement center, or from Amazon.com.

1 Fire Brick
1 Aluminum Angle 1.5" x 1.5" x 24"
4 6" bolts, washers, and nuts

Note: A firebrick is made from a fireproof fiber material. This is not the same as a clay brick. A clay brick will be very hard to drill and work with, and will not withstand the heat of the mini forge. Firebricks are very light and easy to cut with regular tools.

Step 3: Cut the Brick and Drill the Holes

To get started, cut the fire brick into two separate but identical halves. (If you want a bigger forge see the notes at the end of this Instructable.)

In my case I used a standard 10" miter saw with a standard crosscut blade for woodworking installed. The fire brick is easy to cut and simple to work with. As always, wear a dust mask when cutting any materials in your workshop.

One brick will not get any holes. The other brick needs two holes in it. The first hole goes all the way through and needs to be between 1.5" and 3.5" depending on how big you want your forges mouth to be. Smaller forges heat faster, bigger forges work with bigger items. It's a trade off you'll need to make. The second hole goes through the side of the brick and connects with the larger hole. This hole should be the exact size of the nozzle of your propane or MAP torch.

Step 4: Add the Supports

Cut the angle down to the size of your brick halves plus about an inch. Then at each end drill a hole in the angle to allow a bolt to pass through.

Using the four six inch bolts, washers, and lock nuts, strap the two firebrick halves together, making sure the hole for your torch is on the left or right sides (not top or bottom).

Carefully tighten the bolts to make them snug, but no more. The firebrick will easily fracture if you over-tighten it. We're only looking to just hold the brick together and nothing more.

Step 5: Fire Up the Mini-Forge

If your torch has an arched neck you'll probably need to set your forge on a pedestal so that the torch will insert into the side hole correctly. If your torch has a straight neck you can just lay it on its side and set the forge on the a table. A cinder block makes a great pedestal.

Insert the torch into the forge about 1/2". Do not let the nozzle pass into the fire chamber as it will overheat and damage it. If you're torch has a lock on it, you can fire the torch up and set the lock to maintain the flow of fuel.

That's all there is to it! I purchased a set of 18" long needle-nose pliers to make holding items in the torch safe.

Some notes on the design:

1) Many have claimed the forge is unnecessary and items will get just as hot with the torch alone. This could be true if you are heating items that are longer than the forge or very thin. It is not true otherwise. The forge keeps a consistent heat on an item from all sides, which is why it is perfect for knife making and heat treating.

2) You can absolutely make this forge bigger by adding more layers to the forge. Just drill the center of on another brick and use longer bolts. This is an extremely common upgrade. Others have also added additional torches for more heat. Theoretically you could add an infinite amount of additional chamber bricks and torches if you needed to heat long rods for example.

If you enjoyed this project, you will probably like my others! Be sure to follow me here on Instructables! Also be sure to check out my website at TheGeekPub.com and my YouTube channel at YouTube.com/c/TheGeekPub!

Comments

author
ThothLoki (author)2017-04-30

Great job. Did you use k23 or k26 firebrick?

author
WayneEarl (author)2015-09-10

this is great!

Question for you - by using the aluminum support, rather then something iron (support with a higher melting point), does this limit the useage of the mini-forge?

author
TheGeekPub (author)WayneEarl2015-09-12

The outside temperature of the firebrick is room temperature. You could make the supports out of plastic.

author
ScottK29 (author)TheGeekPub2017-04-23

Plastic? Who would have thunk lol. great project. I am currently researching to maybe do this too. I want to make something lol

author
WayneEarl (author)TheGeekPub2015-09-12

That's pretty amazing! Had no idea. Thanks!

author
John T MacF Mood (author)2015-09-15

This is awesome, I have been looking for this very sort of project. I'm considering scaling it up. If our dear author has any ideas on scaling up to perhaps 2' square by 6" high, and temperature ranges possible within such an apparatus, at least one of us would be most grateful.

My objective is to get steel & iron objects to temperatures approaching 1800°F, for forging and reheating, reforging, much as the ancient craftsmen made the Katana blades for Samurai by layering and merging layer upon layer many times, and then tempering them. (I'm leaving off the Seppuku blades, not going there!) I would like to study and work with making culinary knives, as well as custom blades for outdoorsmen - or should I say outdoors-persons. Locally to me, I have a muse in the iron working field, and can pick his brain. The furnace part, I'd need THIS PROJECT... I grew up in Charleston, SC, famous in small part for it's Iron Worked gates and fences.

Thanks so very much, TheGeekPub . You nailed this one. Most excellent!

author

Wow. I'm honored! Thank you so much! If you do this project post some pictures here or on my facebook page so I can see what you made! Facebook.com./TheGeekPub

author

Sure will. I've got a lot of prep work to do this, and collecting parts. A year goes by, and I've made no progress.... It will take a little while longer.

author

In my youth, we would go down to the Fisherman's Terminal (Seattle) and buy scrap propellers which we would cut down to fit into a 4" diam 8" deep crucible. Our forge was what looked like a 6" diam 10" deep concrete pipe closed at one end with a hole in the side (essentially this project scaled up a bit). A fan and propane was our fuel source - we cast a whole lot of items but as far as I know the only piece still extant is a bronze scarab belt buckle. I am pretty sure that the forge was purchased as a set. We did everything in a sand box that was 4' by 4' by 1'. We made a couple of frames to pack damp sand into to make molds. The melting point of bronze is 1742 F, the melting point of copper is 1,984 F - we dropped a penny into crucible with liquid bronze and the penny never lost its shape so that shows the upper limit for this type of forge. We probably could have melted the penny if we had lid. Propeller bronze was really, really difficult to finish - it took forever to cut, polish, file or do anything with it.

author

Sorry to be late replying. Modern pennies are copper plated zinc, so you can check the dates of the pennies, and perhaps get the copper ones. Zinc melts at about 413°C, and begins to boil at 918°C. So careful, VERY careful using pennies.Fumes from melted or boiling zinc can kill you.

Pennies dated 1981 and earlier are copper, after, 1982, they began the copper plating of pennies made primarily of zinc. So be careful.

Some say it's OK to use coinage in metal work, and some disagree. it's a dicey proposition, as technically destroying any form of US Currency Is a federal offense They have bigger fish to fry.. But pennies, well, they don't prosecute it, generally.

author
Wilsknife (author)2015-09-29

Where did you find the fire brick used in this article?

author
TheGeekPub (author)Wilsknife2015-10-01

Amazon is my source.

author
elementman (author)2015-09-29

where did the fire brick come from.

did you get it off amazon?

author
TheGeekPub (author)elementman2015-10-01

Yes. Amazon is my source for these.

author
DirtGrader (author)2015-09-27

That looked like the drift for your Drill Press you heated hope you didn't beat it...Great Video and a very nice Clean looking Mini Forge... Thank You

author
mikem5906 (author)DirtGrader2015-09-28

Shhhh... Don't tell anyone.

author
John T MacF Mood (author)2015-09-15

Part of my inspiration was this video, and being brought up where I was with iron work all over the city, Charleston SC, some of it hundreds of years old.
"Raw Craft with Anthony Bourdain - Episode Four: Bob Kramer" on YouTube:
Kramer made a knife so beautiful, I was inspired to investigate the primary tools of his work. Bourdain credits Mr. Kramer as the best culinary, perhaps the best knifemaker in the world.... Your video is spot on, TheGeekPub!

author
ybaggi (author)2015-09-15


thanks, cool simple project.

Is this an aluminum silicate brick?

Grant Thompson from The King of Random YT channel has used them.

I like that but I am having a hard time (impossible) finding them in Europe.

do other firebricks also cut so easily?

cheers

author
colorfulkreations (author)2015-09-12

I like this tutorial because it gives me the opportunity to make an easy forge. I'm not useing it for metal though. I will use it for glass blowing applications,either way,very informative & easy to make..

author

This is exactly what I was thinking - small scale casting. I have currently converted my microwave to a small kiln (about 4.5" circumference by 1.5" depth); I can cast small things (currently, skulls, hello kitty, and free-form puddles).

author

If you go on amazon you can get 2 kilns,1-3" surface,and 1-5" surface for around $50 for both. I actually started out with a micro kiln&some of the little molds fit,then I went to a 6x6x4 kiln,now it's 11" octagonx13" high! Plus I started flameworking my own beads. I go to bazaar's & craft show's. My jewelry is on www.colorfulkreations.net. I still can't get the hebel,america's far behind in eco friendly building materials,but,our gov't now makes cereal co's list their sugar content! Stupid I know! Hahaha! It's a great country though,40million illegal's can't all be wrong!

author

Awesome! I hope to see some of your work!

author
ChrisB13 (author)2015-09-15

Great tutorial! You should probably mention how fire bricks come in two kinds.
Hard bricks get very hot on the outside and can withstand high temperatures but do not insulate.

Soft fire bricks are what you want here, they cut easily with a knife or saw and insulate as opposed to being used for structure.

If you want to make a large propane forge you generally want to make the structure out of hard fire brick then line the inside with soft fire brick or kaowool.

Also, if you intend to use a flux, you need a slab of hard firebrick "floor" that the flux can drip on as it will eat straight through soft fire brick. You really dont want molten borax dripping out of your forge :)

author
lennartinstructables (author)2015-09-15

Love this instructable! Cheers from Holland !

author
mdeblasi1 (author)2015-09-15

I have seen this very design used to make a mokume-gane kiln!
I know I never post Instructables, but I was planning to make an M.G. oven.
If I do I promise to post photos!

author
ClockworkKeys (author)2015-09-12

if you wanted to would you be able to use a thin piece of firebrick on the back, or none at all?

author
TheGeekPub (author)ClockworkKeys2015-09-12

Most certainly you could, but none at all would kind of defeat the purpose. Too thin and you'll burn yourself if you touch the forge.

author
gizmologist (author)2015-09-10

Very nice! It Just So Happens I have a bunch of surplus firebrick...

author
TheGeekPub (author)gizmologist2015-09-12

Send me a pick if you make one!

author
impied (author)2015-09-10

Super cool!

author
zucchero (author)2015-09-10

Very nice. But just a thought... If the hole of the torch is located at the top of the circle (instead of the middle as it is now) the hot air would move in circles and the heat inside of the forge would be more even. As it is now the propane hits directly the opposite wall and the heat concentrates on that point.

author
TheGeekPub (author)zucchero2015-09-10

That's a great idea. I might try this and make another one and see.

author
MidnightMaker (author)2015-09-09

Nice work!

author
TheGeekPub (author)MidnightMaker2015-09-09

Thanks!!!!

author
BeachsideHank (author)2015-09-08

A very practical piece of equipment for a small scale need, well done!

author
TheGeekPub (author)BeachsideHank2015-09-08

Thank you!!!

author
jbrauer (author)2015-09-08

If you haven't already heard of it, there is a product called ITC-100 that you can smear on the inside of your forge to improve the efficiency. It has some kind of infrared reflective properties that get you hotter, faster. I've used it, and it works, but it is expensive and has to be replaced.

I've built several forges. If you ever have the need to scale up, searching around for 'propane forge burner design' will come up with some inspirational little burners (made from plumbing parts) you can run off a 20-lb propane bottle.

author
TheGeekPub (author)jbrauer2015-09-08

I had not! I'll check it out!

About This Instructable

67,554views

1,413favorites

License:

Bio: I'm Mike, from The Geek Pub. I'm a maker. I love to make things. from woodworking to electronics. Follow along with me!
More by TheGeekPub:The Brain of MorbiusMinion-O-LanternsNinja Star
Add instructable to: