User:Garycookejr/rubberbandgun

Write problem/project Goal
Improve the design of the rubberband gun.

My First Task
Try to find a way to stabilize the wobbly parts on the gun and attach the motor that will drive it.

Summary of actual work over first weekend
I found the problem with the pulley mechanism of the gun that made it wobble and made a decision to replace the pulley mechanism.

Week1 Narrative
I took apart the pulley mechanism on the gun changed the order of the washers to make it spin more smoothly. In the process, I noted that the cylindrical piece of wood in the pulley mechanism is crooked and needs to be replaced. I then tested the gun with a drill attached to the pulley system, and the gun wobbled around excessively as the pulley mechanism turned. I also noted that, with the drill (whose flat bottom was level on the table) attached to the pulley system of the gun, only one of the gun's legs was touching the table, suggesting that either the entire gun itself is built crookedly, or the legs are not the same size.

My Second Task
I will replace the pulley mechanism of the gun.

Summary of actual work over second weekend
I cut a new cylindrical piece of wood for the drive shaft of the pulley mechanism and drilled a centered hole for the drill bit drive mechanism.

Week2 Narrative
I had a cylindrical piece of wood cut with the chop saw and attempted to drill a hole through the center of the end of the cylinder using a power drill with a bubble level taped to it and a vice to hold the wood. The hole did not turn out straight, so I turned to the drill press. I used a specialized tool to find the center of the circle on the other end of the cylinder, and I set up the drill press to drill through the marked center of the cylinder. To do this, I loosened the drill press table and tilted it vertically, using a level. I then tightened it and clamped the cylinder vertically onto it with C-clamps, still using the level to be sure it was still exactly vertical. I made sure the drill bit was positioned on center and used tape to mark where to stop drilling.

My Third task
I plan to find a simpler design for the drive shaft mechanism because even the wood cylinder I made sure I drilled through straight still wobbles a little when attached to the power drill.

Summary of actual work over third weekend
I attempted to redesign the pulley mechanism of the gun to simplify alignment issues by changing the drive shaft from a wooden cylinder to a metal rod.

Week3 Narrative
I tried out various new drive shaft designs including using the ball bearings of skateboard wheels attached by a long screw to serve as the drive shaft, having two screws drilled into both ends of a wooden cylinder to attach it as the drive shaft between two skateboard wheels, and using a printer spooling rod to connect the two skateboard wheels. Of the three, the printer spooling rod wobbled the least and was therefore the most efficient design. I then attempted to attach the skateboard wheels to the gun by drilling screws through the wood blocks on the side of the gun and through the wheels themselves. I tried drilling through a skateboard wheel by itself to see if they were at all penetrable, and it was, with much effort. I then tried drilling through the wood blocks on the side of the gun, but the drill could not get the screw through the entire block. I tried using a drill bit to drill a hole through the wood block to make it easier to drill a screw into it, but it did not make it any easier.

My Fourth task
I must get a working drive shaft attached to the gun so that it can at least function as a rubber band gun.

Summary of actual work over fourth weekend
I finally got a stable drive shaft attached to the gun.

Week4 Narrative
I got new wood blocks, drilled holes into them, aligned them, and got them screwed back onto the gun with a new drive shaft. It is just a simple metal rod going through the holes drilled in the wood. Though this does not reduce friction, the gun does not wobble anymore, which was our primary problem to solve and our only reason for taking the gun apart in the first place. I then wrapped a string around the main and drive shafts to test it with the drill. It spun well, no wobbling at all, but the string broke. A different way of wrapping the string is most likely the solution to this.

Complete Team Page
Team Page