Building A T-Shirt Cannon: Diy Robotics Guide

T-shirt cannons are a fun way to promote events and get crowds excited. They are also a great way to showcase student talent and promote STEM education. While most T-shirt cannons are simple, handheld devices, some ambitious people and organizations have created T-shirt cannon robots that can fire multiple shirts in quick succession. These robots, such as Team 254's Shockwave and The Robocubs' PROJECT: T-Shirt Cannon, showcase innovative engineering and design and have been used to promote their respective teams and sponsors at various events. In this discussion, we will explore the process of building a T-shirt cannon robot, including the required materials, assembly instructions, and potential challenges. We will also delve into the creative ways these machines have been utilized to engage and entertain audiences while sparking curiosity about robotics and technology.

Choosing the right materials

The materials you choose for your robotic T-shirt cannon will depend on your specific requirements, budget, and the availability of parts. Here are some key considerations for choosing the right materials:

PVC Pipes and Fittings

PVC pipes and fittings are essential for constructing the cannon's body, tanks, and barrels. For the main tank, consider using a 4" diameter PVC pipe that is 2 feet long. You will also need two 4" PVC caps and a 3" PVC cap. For the firing mechanism, use a combination of 3" and 1" PVC pipes with corresponding couplers, reducers, and adapters. Ensure you have the necessary PVC cement and primer for secure connections.

Air Compression and Delivery

To generate the required air pressure, you can use a bike pump valve or an air compressor adapter. A sprinkler valve, along with appropriate hoses and adapters, will help regulate and deliver the compressed air. Teflon tape is useful for creating airtight seals on threaded connections. Additionally, consider using a PSI gauge to monitor the air pressure in your system.

Electrical Components

If you opt for an electrically triggered firing mechanism, you will need a 9V battery setup, including battery clips, batteries, and wiring. You will also require switches—one that stays on and one that is momentary. Soldering skills and shrink tubing will come in handy for creating a neat and secure electrical assembly.

Fasteners and Adhesives

Duct tape can be a quick and convenient solution for attaching various components. However, for a more permanent and robust solution, consider using epoxy or glue. Epoxy is particularly useful for sealing any leaks that may occur in your air compression system.

Customisation and Finishing

To personalise and enhance the appearance of your cannon, consider using spray paint. You may also require materials like sandpaper, primer, and filler to prepare and smoothen the surface before painting. Additionally, 3D printing filaments can be used to create custom adapters or other unique design elements.

Remember to select materials that are safe, durable, and suitable for your intended use. Always follow safety guidelines and instructions provided by manufacturers when working with any tools or materials.

Drilling and epoxying

Drilling:

• Begin by taking one of the 4" caps and drilling a hole that is slightly larger than the bike valve. This hole should be just big enough to insert the bike valve snugly.
• Next, take the other 4" cap and drill a hole that allows you to screw in a nipple. Screwing the nipple into the elbow first will make it easier to screw into the PVC. Don't forget to use Teflon tape during this process.
• Now, grab the 3" cap and drill a hole that accommodates the hose adapter. You want the hole to be just large enough to screw in the adapter securely.

Epoxying:

• After inserting the bike valve, nipple, and hose adapter into their respective holes, it's time to seal them in place. Apply epoxy to the inside of the caps to seal any potential leaks that may not be visible.
• Once the epoxy on the inside has dried, repeat the process for the outside to ensure a robust seal.
• Moving on to the firing tank, you'll need to drill a hole for the PSI gauge. Use the same technique as before, screwing in the nipple and adapter and securing them with epoxy.
• Once the epoxy has set in the firing tank, solvent weld the 3" cap to finalise the assembly.
• To check for air leaks, fill the main tank with compressed air using a bike pump or compressor. If you discover any leaks, apply epoxy to seal them.
• Finally, you can use epoxy to secure the electrical components, such as the buttons and switches, in place.

Remember to work carefully and always follow safety precautions when working with power tools and epoxy.

Firing tank and barrel

For the firing tank and barrel, you will need the following:

• 1' section of 3" diameter PVC pipe
• 3" coupler
• 3" to 1.25" reducer
• 1.25" to 1" reducer
• 1" pipe (cut into two 5" sections)
• 1" slip to 1" threaded adapter
• PSI gauge
• 3" PVC cap
• Solvent weld

Start by taking the 1' section of 3" diameter PVC pipe and solvent weld the coupler to it. Next, solvent weld the 3" to 1.25" reducer to the coupler, followed by the 1.25" to 1" reducer. Cut two 5" sections of the 1" pipe and solvent weld them to the reducers. Solvent weld the 1" slip to 1" threaded adapter to the 1" diameter pipe, and repeat this step.

Now you need to choose which one will be the barrel and which will be the firing tank. Take your firing tank and drill a hole for the PSI gauge, using the same technique as before with the nipple and adapter. Screw in and epoxy, measuring so that the gauge is on the appropriate side of the gun. Once the epoxy has set, solvent weld the 3" cap to the firing tank.

The barrel is now complete. You can screw off the barrel to change its size and shoot different projectiles such as potatoes, golf balls, or tennis balls. For firing t-shirts, load the main tank with 100 PSI and the firing tank with 40 PSI.

Additional Steps:

Now that you have completed the firing tank and barrel, you can move on to the next steps:

• Firing Mechanism: You can use an electrical solenoid built into the valve or follow the technique described by crispyjones. For the electrical method, you will need 9V battery clips, 9V batteries, shrink tubing, wire, and switches. Solder according to the diagram and position the switches comfortably. Use epoxy or glue to secure the buttons.
• Attaching the Two Halves: Use duct tape or any other suitable adhesive to attach the two halves of the cannon together.
• Checking for Air Leaks: Fill the main tank with compressed air and seal any leaks with epoxy.
• Testing: Before testing, ensure that you have taken all necessary safety precautions. Cover all holes in the center green solenoid/sprinkler module and fill the cannons with air to ensure they hold pressure. Then, try testing with a payload, starting with something light and small. Shoot at around 30 PSI and gradually increase to 70 PSI if all is functioning correctly.

Firing mechanism

There are two ways to fire your T-shirt cannon: using the electrical solenoid built into the valve or following a technique by crispyjones. Here, we will provide instructions for the electrical side.

You will need the following parts:

• 9V battery clip x3
• 9V battery x3
• Shrink tubing
• Wire
• Two switches, one that stays on and one that is momentary

Now, follow these steps:

• Solder according to the diagram.
• Position the switches on the gun so that it is most comfortable for you.
• Use epoxy or glue to secure the buttons.
• Screw the barrel and firing tank into the sprinkler valve, using Teflon tape on the threading.
• Complete the valve assembly by screwing the other nipple to the elbow, the valve to the nipple, and the hose adapter to the valve, using Teflon tape.
• Insert the hose onto the adapters, tightening using the hose clamps.

Additional Tips

• You can use whatever you want to attach the two halves of the cannon together, such as duct tape.
• To check for air leaks, fill the main tank with compressed air via a bike pump or compressor. Seal any leaks with epoxy.
• The barrel can be screwed off to change the size and shoot other projectiles such as potatoes, golf balls, or tennis balls. For shooting T-shirts, load the main tank with 100 PSI and then fill the firing tank with 40 PSI.

Attaching the two halves

Now that you have the two halves of your cannon ready, it's time to join them securely. This step is crucial, as it will ensure the cannon's structural integrity and prevent air leaks. Here's a detailed guide on how to attach the two halves:

• Prepare the surfaces: Before attaching the two halves, ensure that the surfaces to be joined are clean and dry. Use a solvent to wipe down the areas where the halves will meet. This will remove any dirt, grease, or residue that might interfere with the adhesion.
• Choose your adhesive: Several options are available for adhering the two halves together. One common method is to use PVC cement, which is designed specifically for bonding PVC pipes and fittings. Apply the cement evenly to both surfaces, following the manufacturer's instructions. Another option is to use silicone or epoxy, which can provide a strong and durable bond.
• Apply the adhesive: Carefully apply your chosen adhesive to the mating surfaces of both halves. Ensure that you are working in a well-ventilated area and follow the safety instructions on the product label. Wear gloves and eye protection to avoid any contact with your skin or eyes.
• Clamp and leave to dry: Once the adhesive has been applied, carefully align the two halves and secure them in place with clamps or similar tools. This will ensure that the bond is strong and that the halves don't shift during the curing process. Leave the assembly to dry for the recommended amount of time, which can vary depending on the adhesive used.
• Check for leaks: After the adhesive has cured, remove the clamps and inspect your work. Ensure that the two halves are securely attached and that there are no gaps or cracks in the joint. Fill any small voids or imperfections with additional adhesive and allow it to cure.
• Test for air tightness: To ensure that your cannon is airtight, perform a pressure test. Fill the main tank with compressed air using a bike pump or air compressor. Carefully seal any openings, including the barrel and any valves. Use a pressure gauge to monitor the air pressure inside the tank. If the pressure drops over time, it indicates a leak, and you may need to apply additional adhesive or epoxy to seal it.
• Optional reinforcement: For added strength and durability, consider reinforcing the joint between the two halves. This can be done by wrapping the joint with duct tape or similar high-strength tape. Ensure that the tape adheres well to the surface and overlaps slightly onto each half, creating a strong, continuous bond.

By carefully following these steps, you can effectively attach the two halves of your T-shirt cannon, ensuring a secure and airtight seal. Remember to work safely and always wear the appropriate protective gear when handling adhesives and compressed air.

Frequently asked questions