Cast a Metal Spinning Top That Spins for 7+ Minutes

I love spinning tops! When I need something to help me chill out and relax I grab a top and spin it. Over the past year, I have learned how to cast low temp alloy for the sole purpose of making my own tops. In this Instructable, I will show you how to cast your own metal top that has the possibility to spin for 7+ minutes. The performance and duration of your top will depend on how well it's cast and sanded.

Safety Advisory: Working with metal alloy is dangerous please wear proper safety equipment when casting and detailing: goggles, mask, boots, heat resistant gloves, apron, etc. Also, please use proper supervision when casting metal. If you choose to attempt this Instructable you are responsible for your own safety and materials.

Materials

• Cerrotru Alloy
• Easy Mold
• Corn Starch
• Petroleum Jelly
• 3D Printed Top
• Sulfur Free Modeling Clay
• Wooden Skewer
• Super Glue

Tools

• Do-It Mold Hot Pot 2
• Heat Resistant Gloves and Apron
• 600 - 1500 Fine-Grit Sand Paper
• 60 Grit Sand Paper
• Metal File
• Pliers
• Laser Thermometer
• Clamp
• Rubberbands
• Hobby Knife
• Something To Stir the Metal ( I used a thick piece of steel wire)
• LEGOs
• Plastic Nippers
• Silicone Ice Cube Tray

3D print the spinning top I designed in either PLA or ABS. This will act as our master for the mold-making process. I used an Ender 3 and PLA to print my top. Using 600 grit sandpaper sand down and rough spots on the top. You can find the top I designed here:

If you do not have a 3D printer check your local library, makerspace, or university. Many public libraries offer a 3D printing service. Where I live my public library offers a free 1 hour 3D printing service. The makerspace and university in my town offer a $5.00 per hour printing service. If you cannot find a place to print there are online services available. For example, Shapeways.

Using basic LEGO bricks and base create a structure around the top. Make sure there are at least 1 to 2 studs of extra space between the spinning top master and the walls. The structure should be at least twice as tall as the top. I made my box two bricks tall and ten studs wide. Once you are happy with the box remove the top and fill it with modeling clay 1 brick tall. Do your best to make the clay even and flat. Press the top with its tip facing up about halfway into the clay. Tip: Press the top slightly off-center to leave room for the funnel and exhaust holes. Use a skewer stick to tightly pack the clay around the top. Use the 3D-printed stem of the top to make registry holes in the clay at each corner of the box. These will help align the two-part mold evenly when put together. Using plastic nippers cut two bits of the skewer to make an exhaust and funnel hole. Press half of the skewer bit for the funnel hole in the top center of the clay. Press half of the second skewer bit into the clay at an angle to the left of the funnel hole. See pictures for reference.

Take Part B, the purple putty, and fill half the mold box. Remove it from the mold box and roll it into a ball. Create a ball from part A that is the same size. For accuracy, you can use a kitchen scale to compare weights. Make sure everything is set in your mold box. Easy Mold sets really fast once you mix A and B together, you have about 2.5 minutes to work with it before it becomes hardened. Quickly mix A and B together until it's a consistent color. Roll the putty into a ball and press it into the mold. For the best result, when adding putty to the box start with pressing it onto the spinning top then spreading it to the rest of the box. Make sure the putty fills every corner of the box. Lightly massage the center and each corner of the mold until it begins to stiffen. Let the mold dry for 25 minutes.

Once the first half of the mold cures. Remove it from the LEGO box. Clean off the flashing with a hobby knife. If a piece falls out of the mold replace it back into its cavity. Remove the clay from the box and replace it with the mold. The master and the skewer bits should be facing you. Rebuild the box with an extra layer of bricks. Make sure the top and skewer bits are secure. Cover the mold with a thin layer of petroleum jelly. The jelly acts as a mold release and keeps the two halves of the mold from sticking together. Repeat the process from the last step of measuring out the putty, mixing it, and pressing it into the mold. Let the mold cure for 25 minutes.

Once the second part of the mold is dry remove both parts from the box. Separate the two halves of the mold and remove the spinning top master and the skewer bits. Use a hobby knife to remove flashing. On the second half of the mold at the center of each end slice a thin line from the cavity to the edge. This creates vents so the heat from the melted metal can escape. Use the hobby knife again to widen the funnel hole. Lightly coat the cavity ends of each mold with corn starch. Note: Please wear a dust mask when working with cornstarch. Connect the two halves of the mold together and wrap rubber bands around them. Tip: do not wrap rubber bands too tight. You only need them to hold the mold together. Attach clamps to the bottom of the mold to stabilize it on your workspace. Spread a thin layer of cornstarch under your mold. This will help keep the liquid metal from sticking to your work surface in case some spills on it.

Note: Please wear heat resistant glove and apron, eye protection, and proper footwear when attempting this step. You will be working with liquid metal that is heated to 300F/ 148.889C.

Plugin your Hot Pot 2 and wait for it to heat up to 280 - 300F/ 137.778 - 148.889C. Once the melting point of the Cerrotru alloy is reached carefully place the metal alloy into the pot. Once the alloy melts into liquid use your laser thermometer to monitor it. The alloy is ready to pour once it reaches a temperature of 300F/148.899C. Carefully pour the liquid metal into the mold until it fills both the funnel and exhaust holes. Pour the remaining metal into a silicon ice cube tray. Do not use the tray for ice cube making after the metal has been poured into it. Monitor the mold with the laser thermometer. Once the mold reaches a temp of 70F/21.1C degrees carefully remove the casting.

Use pliers to remove the access metal left behind from the funnel and exhaust holes. Save this metal it can be used in your next casting project. Use a file and/or 60 grit sandpaper to remove flashing. Sand the top smooth using fine-grit sandpaper. Start with 600 grit and work your way up to 1500 grit. Once you are happy with your top's finish rinse it off in cool water and let it dry. Take the 3D printed stem and lightly rough up its bottom with the file or sandpaper. Once the top is dry superglue the stem in place. The stem should fit into the octagon hole at the center of the top. Let the glue set before spinning. Note: I chose not to use a metal stem to reduce weight at the center of the top for longer spin times.

Congratulations you've cast a metal spinning top!

Find a smooth surface. A bowl, mirror, plastic bucket lid, or Beyblade stadium will work for this top. For the best performance use a concave mirror. Firmly grasp the top's stem between your pointer finger and thumb. Place the spinning top's tip on the surface and give your fingers a smooth flick and our top will begin to spin. Do not drop spin this top, it will damage the tip and reduce performance. Do not spin on hard rough surfaces like rock or cement this will also wear down the tip.

Great job on completing this Instructable. If you make one of these tops I would love to see how it came out please post a pic in the comments. If you have questions please leave them in the comments too and I will do my best to respond ASAP.

Happy Spinning!