Nerf compatible gun powered by rubber bands

thingiverse

This is a fully 3D printed Nerf compatible air gun powered by rubber bands. The strength of the gun depends on the number of rubber bands installed. White lithium grease is used to lubricate the inside of the chamber, and the gasket is printed in flexible filament (TPE 80A). Two small rubber bands (~7/8 inch) are needed for the trigger action and pull back effect, while two longer ones are required for the piston. The gun works surprisingly well, and its design is quite impressive. The rail should be compatible with Nerf accessories, but as the designer didn't have any on hand, it was designed against a scope from Thingiverse. This may not make it perfect, but it's still functional. # Printing All STLs are positioned for printing in the standard way. The explodedView.stl and fullView.stl files should not be printed. The cylinder and piston must be printed horizontally to give them strength and ensure they slide with the layers, not against them. The cylinder is printed without supports, but a few layers on the top may not stick perfectly. Cleaning these up before greasing doesn't affect the result. Supports are used for the piston, canonBack, pullerTab, rail, and handle. Inside the handle, only the minimum required supports are left in place; any others can be removed with Simplify3D. The retainerTab must slide smoothly into the canonBack without effort. If it needs force to slide, either sand it or scale it down slightly on the Z axis. If the pullerTab has issues screwing onto the piston, scaling it up 2-3% should resolve this problem. There are no threads in the screw holes; screws are pushed in instead. The gasket is printed in flexible filament (TPE 80A). # Parts You Need to Print To build this air gun, you'll need: * Piston * Cylinder * RetainerTab * PullerTab * CanonBack * Handle * Trigger * Rubber bands (~7/8 inch) * Long rubber bands * Gasket (TPE 80A) * Rail * Tentioners # Assembly ### Parts Preparation / Cleanup Before assembly, make sure the piston is inserted into the cylinder with its retainer slot facing upwards. Play with both parts to smooth and clean them. The retainer tab must move freely in its slot on the canonBack part. The piston arm should slide smoothly into the canonBack and retainerTab. Properly clean the screw/thread of the piston arm/pullerTab before assembly. ### Piston / Gasket Assembly Insert the gasket into its slot on the piston, making sure it sits correctly without being twisted. The thinnest part of the gasket should face back (piston screw side). Grease the gasket and the inside of the cylinder. This will directly affect the strength of the gun. ### Trigger Mechanism Assembly Insert two small rubber bands into the handle, keeping them in place with a screw through the back. Insert the trigger and secure it with another screw. Use a hook-like tool (dentist tool) to bring the rubber bands over the trigger arm in its slot. Pull one of the rubber bands and put it over the retainer tab hook. Slide the retainerTab into the canonBack in its slot. Insert the piston arm through the hole on the canonBack and the retainerTab. Insert the piston into the cylinder, then slide the back of the cylinder into place and push the front into the handle's slot. You may need some force; it's tight. Secure the cylinder to the handle with a screw. ### Putting It All Together Screw the pullerTab onto the piston arm. Insert the rail into the canonBack and attach the canonFront. Insert the tentioners in place, securing them to the canonBack with screws. If you want to be able to disassemble the gun later, make sure there's space between the screw and its socket for a nail. Do some tests to find your preferred rubber bands. The number/ strength of the rubber bands will directly affect the power of the gun but also how hard it is to pull the trigger. When you're happy with your rubber band setup, install the hideRubberBand parts, screw them into the canonBack, and enjoy your new toy! You can watch a quick video of the air gun in action: https://www.youtube.com/watch?v=n1S_KdSi4o4