define the problem
generating concepts
gantt chart
Preliminary sketches
Develop a solution
final sketch
construct and test a prototype
The building process for this project was mostly stress-free. Our original idea was to have a set of gears, and wheel and axle system, and a pulley system. But as we were building the machine, we realized that it would not work out the way that we hoped. So instead of gears, a wheel and axle system and a pulley system, we opted for gears, a chain and sprocket system, and a pulley system. The back part of the machine was used to hold the machine together. Building this structure was the easiest part of the entire build. Once we had the machine completely built, we then realized that we had another issue. Because our machine was built on one side of a platform, the machine wobbled do to the instability. So in order to fix that, we attached some heavy pieces of VEX equipment to the other end to balance out the weight.
evaluate the solution
MODIFICATIONS
Gears, wheel and axle, and pulley system -----> gears, chain and sprocket, and pulley system
Using two gears -----> four gears ------> two gears
Machine built on one side of the platform ------> heavy pieces of VEX equipment to balance out the weight
Gears, wheel and axle, and pulley system -----> gears, chain and sprocket, and pulley system
Using two gears -----> four gears ------> two gears
Machine built on one side of the platform ------> heavy pieces of VEX equipment to balance out the weight
present the solution
Final design
final calculations
1st Simple Machine : Gears
Gear Ratio = Diameter(out) / Diameter(in)
Gear Ratio = 3.5 inches / 2.5 inches
Gear Ratio = 1.4
2nd Simple Machine : Chain and Sprocket
Mechanical Advantage = Diameter(out) / Diameter(in)
MA = 4 inches / 3.25 inches
MA = 1.23
3rd Simple Machine : Pulley System
MA = Number of strands opposing the force of the load
MA = 1
Total Mechanical Advantage
Gear Ratio (1) x Gear Ratio (2) x Gear Ratio (3)
1.4 x 1.23 x 1 = 1.722
Gear Ratio = Diameter(out) / Diameter(in)
Gear Ratio = 3.5 inches / 2.5 inches
Gear Ratio = 1.4
2nd Simple Machine : Chain and Sprocket
Mechanical Advantage = Diameter(out) / Diameter(in)
MA = 4 inches / 3.25 inches
MA = 1.23
3rd Simple Machine : Pulley System
MA = Number of strands opposing the force of the load
MA = 1
Total Mechanical Advantage
Gear Ratio (1) x Gear Ratio (2) x Gear Ratio (3)
1.4 x 1.23 x 1 = 1.722
Conclusion questions
1. For which mechanism was it the easiest to determine the mechanical advantage or drive ratio? Why was it the easiest?
I believe that determining the mechanical advantage for the pullet system was the easiest. The formula for determining pulley mechanical advantage is the number of strands in the system that oppose the force of the load. There was only one strand in the pulley system and it opposed the load. Therefore, the mechanical advantage for the pulley system section of the compound machine was 1.
2. For what mechanism was it the most difficult to determine the mechanical advantage or drive ratio? Why was it the most difficult?
I believe that determining the mechanical advantage for the gears was more difficult. There are many different ways to calculate the gear ratio, (number of teeth, diameter, velocity and torque) but my group and I decided to calculate it by the diameters of the gears. The input gear, Gear A, measured at 2.5 inches. the output gear, Gear B, measured at 3.5 inches. The formula for gear ratio is the output diameter / the input diameter. 3.5 inches /2.5 inches = 1.4. Although this calculation required more work than when finding the mechanical advantage for the pulley, this calculation was not super difficult to figure out.
3. At what value would you estimate the input and output forces of your compound machine? How did you arrive at your estimated values?
The input value for the compound machine is a human input. Therefore, the input can easily be manipulated and changed. I estimate that the input value for my compound machine is about .75 - 1.00 of a pound. It takes a good amount of effort to turn the wheel that turns the gears. The input value can be anywhere in this range. This is just an estimate, so the input value could be more or less, but I chose this range because that is about how much effort force my team and I have been using throughout this process.
The output force of the compound machine can be anywhere from 1.2915 - 1.722 pounds. When one is calculating the mechanical advantage of an entire system, they must multiply all of the individuals mechanical advantages for each of the different systems together. I estimated that the human input force can be anywhere from .75 - 1.00 of a pound. The total mechanical advantage for the machine is 1.722. I multiplied .75 x 1.722 = 1.2915. 1 x 1.722 = 1.722.
4. What modifications could you make to your compound machine to make it more mechanically efficient?
The machine completes the task (raising a ping pong ball 2 feet) but it moves very slowly. In order to increase speed and mechanical advantage, we could change Gear A to a bigger gear so that we would need less input force. By doing this, the machine would require less input force and the output force would increase. The ping pong ball would rise faster.
I believe that determining the mechanical advantage for the pullet system was the easiest. The formula for determining pulley mechanical advantage is the number of strands in the system that oppose the force of the load. There was only one strand in the pulley system and it opposed the load. Therefore, the mechanical advantage for the pulley system section of the compound machine was 1.
2. For what mechanism was it the most difficult to determine the mechanical advantage or drive ratio? Why was it the most difficult?
I believe that determining the mechanical advantage for the gears was more difficult. There are many different ways to calculate the gear ratio, (number of teeth, diameter, velocity and torque) but my group and I decided to calculate it by the diameters of the gears. The input gear, Gear A, measured at 2.5 inches. the output gear, Gear B, measured at 3.5 inches. The formula for gear ratio is the output diameter / the input diameter. 3.5 inches /2.5 inches = 1.4. Although this calculation required more work than when finding the mechanical advantage for the pulley, this calculation was not super difficult to figure out.
3. At what value would you estimate the input and output forces of your compound machine? How did you arrive at your estimated values?
The input value for the compound machine is a human input. Therefore, the input can easily be manipulated and changed. I estimate that the input value for my compound machine is about .75 - 1.00 of a pound. It takes a good amount of effort to turn the wheel that turns the gears. The input value can be anywhere in this range. This is just an estimate, so the input value could be more or less, but I chose this range because that is about how much effort force my team and I have been using throughout this process.
The output force of the compound machine can be anywhere from 1.2915 - 1.722 pounds. When one is calculating the mechanical advantage of an entire system, they must multiply all of the individuals mechanical advantages for each of the different systems together. I estimated that the human input force can be anywhere from .75 - 1.00 of a pound. The total mechanical advantage for the machine is 1.722. I multiplied .75 x 1.722 = 1.2915. 1 x 1.722 = 1.722.
4. What modifications could you make to your compound machine to make it more mechanically efficient?
The machine completes the task (raising a ping pong ball 2 feet) but it moves very slowly. In order to increase speed and mechanical advantage, we could change Gear A to a bigger gear so that we would need less input force. By doing this, the machine would require less input force and the output force would increase. The ping pong ball would rise faster.