Casting Molds for 2.5lb, 5lb, and 10lb Concrete Olympic (2 inch) Weights

thingiverse

In unusual times, this makes perfect sense. Although concrete isn't ideal for making weights due to its relatively low density compared to iron or steel, it's incredibly heavy and can be a viable solution when gyms are closed and weightlifting equipment is in short supply. Here's a collection of models that you can use to cast your own Olympic-sized (2-in center) concrete weights in three different sizes: 2.5lb, 5lb, and 10lb. Each part consists of three main components: * The mold itself: + Floor: This is the base plate that you'll attach the walls to. + Walls: These are the side pieces that form the shape of your weight. + Center axis: A small plastic piece that serves as the center of your new weight, protecting your barbell from damage when adding or removing weights. * Optional overflow dam: A small piece that helps prevent concrete from overflowing into the center of your weight's axis. ## Casting Your Weight 1. Assemble your mold: * Attach the walls to each other using blue painter's tape on the outside edge. * Snap together any multiple parts of the floor by hand, or gently use a hammer if necessary. * Place the floor upside down over the wall assembly and attach it with tape. * Flip the mold over. 2. Secure the center axis in the center of the mold using a hammer to get it flat. 3. Insert the overflow dam (optional). 4. Prepare your concrete mixture and pour it into the mold, packing it firmly to ensure even distribution. 5. Wait for the recommended amount of time (usually around an hour). 6. Remove your new weight from the mold by: * Removing the tape holding the walls together. * Gently prying off each wall piece. * Carefully removing the floor from the weight. ## Getting an Accurate Weight You won't get extremely accurate weights, as factors like humidity can affect the weight of concrete. However, using the following pattern with CementAll rapid-set concrete, you can achieve a weight within two ounces: ### 2.5 lbs * Concrete Mix: 1060g * Water: 131g ### 5 lbs * Concrete Mix: 2119g * Water: 262g ### 10 lbs * Concrete Mix: 4239g * Water: 524g To calculate your own weight, use the following formula: ``` total_weight = target_weight * 1.05 concrete_weight = total_weight * 0.89 water_weight = total_weight * 0.11 ``` This formula aims for an 89:11 concrete-to-water ratio and slightly over-shoots the weight, knowing that some concrete will be lost during casting. ## Making Bigger Weights You can easily make bigger weights by: 1. Copying the Fusion 360 project for the 5lb weights. 2. Adjusting the diameter of the circle in the main sketch to match or slightly less than the standard diameter of weights at that weight. 3. Adjusting the position of the "Weight Ceiling" plane until the "mass" property of the "Concrete" body matches your desired weight. You may also need to adjust the height of the walls.