Brass knuckles, also called "iron fists", are small arms used in martial arts. While they are not immediately lethal like other offensive tools, they are still very dangerous and must be used responsibly. If you have the right tools, you can even build one at home.
Steps
Part 1 of 3: Project
Step 1. Find a reference image
Use the online search engine of your choice to find images of traditional brass knuckles; choose the best one and save it to study it.
- The photograph should clearly show the front of the weapon; it does not need to be to scale, but the outline should be well defined.
- If you have memorized the look of the brass knuckles you would like, you don't need to use a reference photo; you can then skip this step and move on to the next step if you wish.
Step 2. Draw a sketch on paper
Using the guide image you downloaded, take a regular sheet of paper and draw the brass knuckles you want to build. You need to draw a full-size project, suitable for your hand.
- For the hand of an average adult man, the distance between the base of the grip and that of the hole in the middle finger should be between 30 and 35 mm.
- Each finger hole should be 25-27mm in diameter; instead of making perfectly circular openings, shape them with a slightly oval shape.
- After drawing the brass knuckles, carefully cut it out; proceed along the outer perimeter and cut out the holes.
Step 3. Return the design to the metal
Fix the "stencil" with adhesive tape on the metal plate that you have decided to use and trace the outlines with a permanent marker.
- You can also draw the edges in pencil first; this way, you can correct any errors. However, you will then have to go over the drawing with a permanent marker.
- After transferring the design to the metal, you can remove the paper template.
- For this project it is recommended to use Avional AA2024 aluminum alloy or 7075 ergal alloy with a thickness of 7-12 mm; you can also opt for a brass plate (of the same thickness), but it is a more difficult metal to work with.
Part 2 of 3: Cutting
Step 1. Put on safety glasses
Before cutting the metal you need to put on glasses to repair the eyeballs.
Since you are working with a material that is hard to pierce, there is a risk that the drill bit will break midway through the process; if you are not wearing the protectors, the fragments could fly towards your eyes causing a serious injury
Step 2. Drill holes along the outline
Engage a 3mm bit on an electric drill and go over the entire perimeter of the weapon.
- Do this on every line you drew, including the finger holes.
- The holes should be close to each other but still well defined; as a general rule, do not leave a space greater than the radius of the hole (about 1.5 mm) between one and the other. Also, never overlap them, as the tip may lose grip.
- If possible, you should use a corded electric drill and not a cordless one as the latter tends to overheat and force you to take numerous breaks.
Step 3. Use an awl to detach the brass knuckles
Place the tip of a flat screwdriver in the spaces between the various holes and hit the handle with a hammer; continue in this way until the tip breaks the metal that keeps the weapon connected to the plate.
- You have to proceed in this way along the entire perimeter by breaking one at a time the small "bridges" between one hole and the other that you have previously obtained with the drill; don't forget the inner lines as well as the outer ones. You must use the screwdriver on both the front and back of the plate.
- This stage of the work requires a lot of time and physical strength.
- You can also use a hacksaw if you are able to control the blade along the curved lines; however, it is not a mandatory tool, you can do just fine with the screwdriver and hammer.
Step 4. Detach the sketched brass knuckles from the metal block
After breaking all the remaining flaps between holes, you should be able to remove the shape from the plate using only your hands.
- At the end of this step you should clearly see the shape of the weapon; the edges are very rough, handle them carefully.
- Recycle or otherwise reuse the scrap metal you no longer need for the rest of the project.
Part 3 of 3: Finishing
Step 1. Smooth the grooves
Use a Dremel-like rotary tool to smooth the rough edges of the weapon; engages a specific round tip for soft metals.
- If you observe the outline of the brass knuckles, you should notice the presence of sharp notches whose concave parts originate from the holes you made with the drill, while the outer edge is in correspondence with the "edges" that you broke with a hammer and screwdriver.
- Bring the tip of the Dremel over the protrusions of these notches and sand them until they are smooth and flush with the concave portions.
- If you encounter difficulties at this stage, hold the brass knuckles steady with a bench vise; insert a piece of paper or fabric between the jaws and the gun to prevent the metal from scratching.
Step 2. File the small details
When you've cleared most of the grooves, switch to metal files to make the edge even smoother.
- Use a circular section to sand the notches that are inside each finger hole, while a triangular section is more suitable to create indentations on the outer edge between one finger pocket and the other. The flat file is perfect for smoothing out the rest of the outline.
- Technically, you can avoid grinding the weapon with the Dremel as long as you use such files; however, without the support of a power tool, finishing takes a long time and this method is not recommended.
- Again, lock the weapon in a bench vise while filing the edges.
Step 3. Sand the brass knuckles
Even though the outline now has a much more rounded appearance after the filing step, you should still smooth it out further with sandpaper.
- You can do it by hand, you don't need a belt grinder or other power tool.
- Work respecting the phases. Start with the rougher sandpaper (60 or 80 grit) and smooth the edges until you are happy with the result; then move on to smoother and smoother sheets, until you reach 320 or 400 grit ones.
- If you like, you can put the finishing touches on with water-based sandpaper. This is an optional step and may not be necessary if the outline already looks very smooth.
Step 4. Polish the brass knuckles
Take a 00-grit steel wool scourer and rub all the metal with small circular motions; works on both sides of the weapon.
- You can also polish the edges, although this is not strictly necessary. During this phase, focus your energy and attention on the flat sides.
- When finished, the metal should be less dull and more shiny.
Step 5. Apply metal polish
Spray or spread it all over the piece, including edges and flat parts.
- You can use both a metal cleaner and a polish; in both cases, make sure it can be applied to the aluminum, to avoid accidentally damaging or blackening the material.
- Smear the product thoroughly on the metal. Continue buffing and scrubbing with a soft cloth until you have wiped away any moisture from the polish.
Step 6. Grab the weapon
At this point the brass knuckles are finished and ready to "wear". Slip it into your hand to make sure it fits your fingers and palm well.
- Your fingers should enter the holes smoothly and you should be able to close your hand into a fist without any discomfort.
- If the weapon is too large, you cannot make any changes, but if the holes are too narrow, you can try to widen them slightly according to the amount of metal present. For these touch ups you should file the metal with a Dremel or file instead of using a blade or awl.
Warnings
- Do not to use never the brass knuckles to injure another person or animal; this weapon is for display or self-defense purposes only.
- Be aware of the legal restrictions; in many countries the brass knuckle is considered an illegal weapon and you cannot even own it, in others it is only outlawed if used to commit a crime. Before building one, inform yourself about the current legislation.
