A rubber band machine gun!
Make the mini-version at home!Please add pictures of your version in the comments! If you see an improvement to make, let everyone know!
HOW IT WORKS
The rubber bands are arranged in rows (levels front to back) and stacks (layers of rubber bands on each peg).
As string unwinds, each pass around the cylinder slips off one stack of rubber bands that are held by the pegs. On the second pass, the sting slips off the layer of rubber bands attached just below the previous stack. When these stacks are depleted, the string progresses to the next row.
Each layer can be loaded by placing a layer of string around, then a layer of rubber bands and then a layer of string and more rubber bands. This is why the video shows the string wrapped several times at each row of pegs.
FIRING MECHANISM
Build the cylinders from paint rollers available at a home improvement store for a few dollars. Get one of the short kinds of roller and one of the long kinds of roller. Get PVC pipe that will slide onto both rollers and fit them snugly. Cut the pipe to cover the rollers.
Drill holes the width of the dowel rod that are spaced 1/4 inch apart all the way around. Cut the dowel rods so that they go into the tube (flush with the inside) and stick out 1/3 of an inch. Glue in the dowel rods using a hot glue gun and use a rag to wipe the glue smooth around the base (without burning yourself on the hot glue).
BUILD THE TRIGGER
Make the trigger from a button that you can press and stops when released. Sting a wire from the button to a battery, and another to the terminal on the motor. Connects the other terminal on the motor to the other side of the battery.Improve the design with a quieter motor so that you can hear the rubber bands hit the target.
BUILD THE STOCK
Glue sheets of cardboard in the mock up to make them 3/4 of an inch thick so that you can experiment with different shapes before you cut them out of the plywood. Make the handle/stock comfortable and stylish. Provide a part to glue accross the top of the handle to form a horizontal "T" to attach the paint roller handles later.
Once the cardboard handles are satisfactory, trace them onto the plywood and cut them out using a coping saw. Use wood glue to attach the wood togther and sand paper to take off corners/splinters. Glue the paint roller handles in at the top of the "T" with gorilla glue. Make sure that they are able to still turn freely and that they are held straight while the glue cures.
Use pipe clamps to mount the motor on the stock underneath a "T" arm near the short roller without touching it. Use a rubber band (or rubber bands tied together) to make a belt that the motor can use to drive the short roller. On the short roller, glue the end of the string and wrap a length that is long enough to encircle the positions on the big tube as the rubberr band ammunition is loaded. If the string is too short, tie two pieces together using a sheet bend or any knot that works.
PROJECTILE AMMO:
Experiment with different types of ammo. Buy rubbery surgical tubing and slice into rubber bands to get custom sizes. For really small versions, rubber bands from braces might do.
PARTS LIST:
Firing Mechanism:
2 paint rollers (one long and one short)
PVC pipe (to fit the two rollers)
Dowel rods (chopstick to pencil sized diameter)
String
Electronic Trigger Parts:
Motor (small but strong)
Button
Batteries (in battery holder)
Wire
Stock:
Small scraps of plywood
Wood Glue
TIPS:
If the PVC slips on the rollers, glue them in place with a hot glue gun.
If the motor runs in reverse, switch the wires to different sides of the batteries.
Use a finish on the wood if desired (follow package instructions).
WARNING:
Hot glue is hot. Sharp things are sharp. Always wear appropriate eye protection when near this device or working with tools. Read and follow all instructions that come with tools you use. Do not build this device if you are not wise enough or old enough to use the tools. Make sure that this rubber band gun does not look like a real gun because of the risks associated. Stay away from any fast moving parts. It is a good idea to make a housing to cover this part of the machine. Remember that the motor will get hot.
