Explosive Combustrion Projectile Gun

This Alcohol Combustion Gun can be very dangerous if used incorrectly, so be careful.  

This gun operates by igniting rubbing alcohol to create an explosive rush of air which propels a projectile 200+ feet, (I have measured the distance). The potato cannon inspired this gun. But I thought that instead of using PVC pipe and a potato, I would use a 3D printed combustion chamber and bullet. The ignition source is a piezo grill lighter. You will need to buy one here, or one similar. I have also included fusion 360 modeling files so that you can edit or remix the design. Have fun and be safe! 

Print Instructions:

The following print instructions are recommended for the strength of the 3D printed parts, as the gun possibly could explode if the parts were too weak. The settings below should be well qualified.

Combustion Chamber:

• Material: PETG, (PETG is more heat resistive than PLA. PLA can work, but warping may occur).
• Walls: 3
• Infill: 30%
• Supports: Yes, will need supports for the handle

Combustion Chamber's Lid:

• Material: PETG
• Walls: 3
• Infill: 20%
• Supports: Yes

Projectile:

Note: 3D print the Test Bullet Tolerances file to see which bullet will work the best with the chamber diameter. I found that the 0.5 mm projectile worked the best for my print.

• Material: PLA or PETG
• Walls: 20
• Infill: None, (filled with perimeters)
• Supports: None

Barrel Extension:

Note: The barrel extension may help a little with range, but not significantly from my observations. Also, you can print multiple barrels and stack them on top of each other.

• Material: PETG
• Walls: 3
• Infill: 30%
• Supports: None

Assembling Instructions:

You will need:

• A hot glue gun
• Some wire, (thin enough that two wires can fit through the ignition hole).
• A wire stripper
• A peizo grill lighter, (Link, or one similar).

1. Cut two wires so that they reach both the igniter and the ignition hole.
2. Strip both the wires.
3. Hot glue the two wire's insulation so that the ends touch the leads of the igniter.
4. Hot glue the igniter to it's place on the handle
5. Run the wires through the ignition hole and hot glue them in place

I hope that made sense :)

Pictures:

You will need to create your own push rode to push the bullet to the end of the barrel. I just used a full sized pencil. I might add a push rod to this model in the future.

Happy Printing!