10kg Concrete Weight Plate Mold

I have designed the 10kg weight plate mold to be 350mm wide with a height of 48mm. The center hole is for standard bars (Approx 25mm diameter weight bar). NOTE This will not fit Olympic bars as they are wider. If you scale the center circle to be 51 - 52mm for the external diameter if you wish to fit the plate onto an Olympic bar (Olympic bars are 50mm). You will probably also need to raise the height of the walls and centre circle to fit the the concrete mix in.

The walls are a 60 degree slice of the circle so it can fit onto many printer beds. You need 6 parts in total. Then they can be bolted together.

Making the Plates

• Cut a MDF board to larger then the circle size and covered it in parcel tape so the concrete doesn't stick to the board.

• I then drew a circle of 350mm so I knew where to place the mold once bolted together.

• Bolted the 6 outer wall parts together using top and bottom holes. If you want drill them out wider to a larger bolt through. I used washers either side to help spread the load but not required.

• I measured 175mm from the center to the inside edge of where the outer wall part screws down to the board and screwed the wall down.

• Screw the center circle in the middle of the circle and place the top cap on. This is to stop concrete getting in there when you pour and level it.

• Silicon sealed the outer wall parts where it meets the MDF sheet to avoid the concrete mix seeping out under the mold.

• Silicon seal the outside edge of the center circle where it meets the board.

• Apply silicon sealant to the edges where the outer wall parts are bolted to each other to stop any water seeping through the join.

• The numbers and letters can be screwed to the bottom of the wooden board if you want the plates to have the weight imprinted on them. Remember to fit these in reverse so they look correct when the concrete plate is removed from the mold. The chamfered hole should be facing up when screwed to the MDF.

I have done some plates with rubbing some used vegetable oil on the MDF and plastic parts to stop the concrete sticking and I have done it without. In both cases the plates have formed ok and the molds have come out with minimal damage to them.

I used a pre mix bag of concrete called cemix nosteel. This has special fibers in it to create more strength then usual concrete. I recommend using this type. As the bags are 20kg (Mine all measured about 22kg so had plenty for adding more mix) I measured 10.3kg into a bucket and then mixed about 1.15L of water into the mix. This then dried to a dry weight of 10kg.

The first time I measured 10kg exactly of dry mix and used 1L of water as per the instructions on the bag, but these dried to a weight of 9.7kg, hence why I used 10.3kg of dry mix and slightly more water on the second set. You may need to tweak this ratio and weight for different manufacturers.  Its best to be heavier then the 10kg as you can always grind the excess off to get to the 10kg weight.

I then poured the mix into the mold a bit at a time so lessen the impact of it hitting the board and bowing the sides. Then I vibrated the mold to release any air bubbles and then used a flat edge to smooth the exposed top edge.

I left mine for about 3 days before unbolting the mold and removing the screws. Then I carefully removed the mold from the sides of the concrete plate. Removing it from the letters I just had to lever the plate up and it eventually popped off.  I then used a large socket to knock the center circle out from the top to the bottom (It has a slight 1mm taper inwards going from the the screw hole at the bottom to the top.)

Then I wrapped it in a damp towel for a further 5 to 7 days to fully strengthen.

Print Settings

Height 0.2mm

Material : PLA+ or PETG

Perimeters : 3 (Increase to make it stronger)

Infill : 20% Again increase if you want it stronger

No supports required

I used PLA+ and this kept the concrete in fine with no leakages. When I removed the mold form the concrete, I did break 3 of the 6 outer rim parts every time so maybe using PETG or more infill and more perimeter may stop this from happening.