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!