How To Make Hex Dumbbells

If you’re looking for a cost-effective and customizable strength training solution, learning how to make hex dumbbells is a fantastic project. Manufacturing hexagonal dumbbells involves shaping metal or molding concrete into the distinctive six-sided form, but you can achieve similar results at home with simpler materials.

This guide provides clear, step-by-step instructions for two primary methods. Whether you’re a DIY enthusiast or just need some weights for your home gym, you can build durable hex dumbbells that meet your exact weight requirements.

We’ll cover the tools you need, material choices, and safety tips to ensure your project is a success.

Creating your own hex dumbbells is a straightforward process that centers on two main approaches: casting with concrete or fabricating with steel. The method you choose depends on your available tools, budget, and desired finish.

Concrete dumbbells are generally cheaper and easier for most people to make. Steel dumbbells are more durable and professional but require more specialized tools like a welder.

Below, we outline the core considerations before you start either project. Getting these basics right will make the entire build process smoother and safer.

Essential Tools And Materials

Gathering everything you need before you begin is crucial. Having your tools organized will prevent interruptions and help you work more efficiently.

Here is a basic list for both the concrete and steel methods. Some items, like safety gear, are non-negotiable for both.

Safety Gear: Safety glasses, heavy-duty gloves, dust mask (for concrete mixing), and hearing protection (for grinding/cutting metal).
Measuring Tools: Tape measure, calipers, a scale for weighing final products, and a level.
Basic Workshop Tools: Adjustable wrenches, clamps, a sturdy workbench, and a vise.
For Concrete Dumbbells: Hexagonal mold material (PVC pipe, wood forms), concrete mix, rebar or wire mesh, mixing bucket, trowel, and release agent (like cooking oil).
For Steel Dumbbells: Steel pipe or solid bar (for the handle), steel plate (for the heads), a welder and welding supplies, an angle grinder with cut-off and grinding discs, and a drill with metal bits.

Choosing Your Design And Weight

The classic hex dumbbell design features a cylindrical grip with two hexagonal plates fixed at each end. The hex shape prevents the dumbbell from rolling away when placed on the floor.

You must decide on the final weight for each dumbbell. This determines the amount of material you need. Remember to account for the weight of the handle itself in your calculations.

For concrete, you’ll need to calculate the volume of your mold and know the density of your concrete mix. For steel, you can calculate the weight of steel plates based on their thickness and diameter.

It’s a good idea to sketch your design with dimensions. This reference will be invaluable during the cutting and assembly phases.

Calculating Concrete Weight

Standard concrete has a density of about 150 pounds per cubic foot. To find the volume of a hexagonal prism (the head), you can use online calculators or the formula: Volume = (3√3 * s² * h) / 2, where ‘s’ is the length of one side and ‘h’ is the thickness.

For simplicity, create a test mold with your chosen dimensions, fill it with water, then pour that water into a measuring jug to find the liquid volume. This gives you a close estimate for your concrete volume.

Calculating Steel Weight

Steel weighs approximately 490 pounds per cubic foot. The weight of a steel plate can be estimated with this formula: Weight (lbs) = Thickness (inches) x Width (inches) x Length (inches) x 0.283.

For round plates turned into hexagons, calculate the weight as a circle first, then account for the small amount of material you’ll grind off to create the six sides.

Method One: Casting Concrete Hex Dumbbells

This method is excellent for beginners and yields very solid, functional weights. The key is in creating a strong mold and ensuring the handle is securely embedded.

Creating the Hexagonal Mold

You can construct a reusable mold from wood or use a section of thick-walled hexagonal PVC pipe. Wood molds offer more size flexibility, while PVC provides a smoother finish.

If using wood, cut six identical trapezoidal pieces and fasten them together with screws and glue to form a hexagonal tube. Seal the inside seams with silicone caulk to prevent concrete leakage and make demolding easier.

Apply a generous coat of release agent (cooking spray or commercial mold release) to the entire interior surface. This step is critical for getting your concrete block out intact.

Mixing, Pouring, and Setting the Concrete

Mix your concrete according to the package instructions. Aim for a thick, oatmeal-like consistency; too much water weakens the final product.
Pour concrete into your mold halfway. Insert your pre-cut rebar or wire mesh for reinforcement. This prevents the dumbbell head from cracking under stress.
Take your handle (a steel pipe, thick dowel, or even a pre-made dumbbell handle). Coat the section that will be inside the concrete with release agent as well.
Insert the handle into the wet concrete, centering it carefully. Use a level to ensure it is perfectly straight. Then, fill the mold the rest of the way with concrete.
Tap the sides of the mold vigorously with a rubber mallet to remove air bubbles. Smooth the top surface with a trowel.
Let the concrete cure for at least 48 hours in the mold. Keep it damp by covering it with plastic; this allows for proper curing and increases strength.
After curing, carefully disassemble the wooden mold or slide the concrete out of the PVC pipe. You may need to tap it gently. Allow the concrete to air-cure for another week before use.

Method Two: Fabricating Steel Hex Dumbbells

This method creates commercial-grade, permanent dumbbells. It requires metalworking skills and tools, particularly welding. Always prioritize safety when cutting and welding steel.

Cutting and Shaping the Steel Components

Begin by cutting your handle material to length. A standard dumbbell handle is about 5 to 6 inches long for a tight grip, but you can customize this.

Next, cut your steel plate into squares or circles slightly larger than your desired hexagon size. You will grind these into hexagons later.

Mark the center of each plate and drill a hole just large enough for your handle to fit through snugly. A drill press is ideal for getting a straight, clean hole.

Use an angle grinder with a cut-off wheel to rough out the hexagonal shape from your plates. Then, switch to a grinding disc to smooth the edges and perfect the six flat sides. Always wear your safety glasses and gloves during this process.

Welding the Assembly Together

Proper welding is what makes the dumbbell safe. If you are not an experienced welder, seek help from someone who is. A poor weld can fail during use and cause injury.

Slide one hex plate onto the handle, pushing it flush against your pre-marked stopping point or a welded collar. The handle should protrude about 1 to 1.5 inches on each side for the plates.
Secure the assembly in a vise, ensuring everything is square. Tack-weld the plate in place at two or three points.
Remove it from the vise and complete a full weld around the joint where the plate meets the handle. Use a strong weld bead to ensure a solid connection.
Repeat the process for the second hex plate on the opposite end of the handle. Double-check that both plates are parallel to each other.
Let the metal cool completely. Then, use your angle grinder to clean up the weld beads, making the joint smooth and neat. You can leave a rustic look or grind it flush for a professional appearance.

Finishing And Protecting Your Dumbbells

A good finish protects your dumbbells from rust (for steel) or chipping (for concrete) and improves their look and feel.

Finishing Concrete Dumbbells

Once fully cured, you can sand down any rough spots on the concrete with coarse-grit sandpaper. Wipe away all dust.

Apply a concrete sealer with a brush. This will protect the surface from moisture and wear. For a colored finish, you can mix concrete dye into the wet mix or paint the cured dumbbell with a durable outdoor paint.

Finishing Steel Dumbbells

After grinding, remove all rust, scale, and oil from the steel using a wire brush or sandpaper. Wipe it down with a degreaser like acetone.

Apply a primer designed for metal. Once the primer is dry, apply your choice of enamel or rust-resistant spray paint. For the handle, consider using a textured paint or athletic tape for a better grip.

Some people prefer a bare metal look. If so, you must regularly oil the steel to prevent rust from forming, especially if you sweat on them.

Safety Checks And Quality Assurance

Before you start lifting with your homemade equipment, you must perform thorough safety inspections. This is not a step you can skip.

Visual Inspection: Look for large cracks in concrete or cracks in welds on steel. Check for significant chips or deformities.
Weight Verification: Use a reliable scale to weigh each dumbbell. Ensure they are a matched pair if you made two.
Handle Integrity Test: For concrete, try to gently twist the handle. It should not move at all. For steel, tap the welds with a hammer; they should sound solid, not produce a dull thud.
Load Test: Start by using the dumbbell for light exercises over a soft surface like grass or a mat. Gradually increase the load over several sessions to test its durability under real use.

Never use a dumbbell that fails any of these checks. It’s better to remake it than risk an accident.

Troubleshooting Common Issues

Even with careful planning, you might encounter some problems. Here are solutions to frequent issues.

Concrete Won’t Release From Mold

This usually means you didn’t use enough release agent. Try tapping the mold more firmly on all sides. You can also try to carefully pry it apart if it’s a wooden mold. For future casts, be more generous with the cooking spray or oil.

Weld Looks Weak or Bubbly

A poor weld often indicates incorrect welder settings, dirty metal, or lack of skill. Grind the bad weld away completely and re-weld it. Ensure the metal is clean and shiny before you start, and practice your technique on scrap pieces first.

Dumbbell Heads Are Not Aligned

Misaligned heads can throw off your balance during exercise. For steel dumbbells, you may need to cut the weld and reposition the plate. For concrete, it’s harder to fix, so careful placement during the pour is essential. Using a level and clamps can help immensely.

Frequently Asked Questions

What Is The Cheapest Way To Make Hex Dumbbells?

The concrete method is almost always the most affordable. The primary costs are a bag of concrete mix, some scrap wood or PVC for molds, and a piece of pipe for the handle. You can often source these materials for very little money.

Can I Use Plastic For The Hex Heads Instead?

While you could mold plastic, it is not recommended for weight plates. Filling plastic with sand or concrete can work for lighter weights, but plastic is not as dense as metal or solid concrete, so the dumbbells would be very large for a given weight. It also may crack under repeated impact.

How Do I Make Adjustable Hex Dumbbells?

Making truly adjustable hex dumbbells like commercial versions is complex. A simpler approach is to create multiple pairs at different fixed weights. Another idea is to make a single handle with a locking collar system and several pairs of interchangeable hex plates, though this requires precise machining.

What Is The Best Material For The Handle Grip?

For steel handles, knurling (a textured pattern) provides the best grip but requires a metal lathe. A good alternative is to wrap the handle with high-quality athletic tape or use a textured rubber spray paint. For concrete dumbbells, using a steel pipe handle and adding a rubber grip sleeve is effective.

How Long Do Homemade Concrete Dumbbells Last?

With proper reinforcement (rebar), good quality concrete mix, and a protective sealer, homemade concrete dumbbells can last for many years in a home gym. Avoid dropping them directly onto hard surfaces from height, as this can cause them to chip or crack over time. Storing them in a dry place also extends there lifespan.