Team 50 Design Log Book MEMS 0024 Design Project 2: Big Machine
Table of Contents 1) Problem Statement............2 2) Idea Generation..........4 3) Input Requirements...........5 4) Output Requirements...........7 5) Preliminary Design......8 6) Final Design.13 7) Bill of Materials...17 1
Problem Statement The following is a description of the design requirements of segment 50 and, for completeness, the segments immediately before and after the design zone. A sketch of zone 50 on the schematic of the Big Machine s path is presented on the following page. The design area, zone 50, is located outside the door of Benedum 229 closest to the tutoring area and the bottom end of the ramp located around the back of the classroom. The design zone begins at the top of two stairs, turns right 90 degrees past the tutoring area on the left, and reaches a short hallway that approaches a descending staircase. Immediately outside of the doorway to room 229, a half-wall juts into the hallway, to which a railing for the two stairs is attached. Beyond this half-wall, a short ledge extends several feet until it reaches the stairs leading up to the tutoring area. The group before is responsible for zone 49, located at the bottom of the ramp descending toward the two stairs that mark the beginning of section 50. This zone passes two doorways as it approaches zone 50: the doors to rooms 229 on the left and 227 on the right, and the group in this zone is responsible for not obstructing those doorways with their machine. The group after, group 51, shares the area between the two stairs and the larger descending staircase, and is responsible for covering the stretch of hallway immediately in front of that staircase. This group has no special requirements, so it is also responsible for a Pitt theme. The machine to be designed (segment 50) must descend the two stairs and cross the intersection without blocking the intersection or interfering with the two doors previously mentioned. Additionally, it would probably be beneficial if the short railings on either side of the two stairs were not used in the design, so that they can still be used by people descending the stairs while the machine is set up. 2
The Design Zone (Zone 50) on the schematic of the Big Machine s Path: 3
Idea Generation The following list represents some possible mechanisms/design ideas that were generated in the process of addressing input and special requirements of the machine: Dominos topple over. A mannequin falls over. A spring-loaded gun or similar shooting mechanism is triggered. A speaker generates vibrations that trigger the next action. A hairdryer or fan turns on to blow something across the hallway/intersection. A ball rolls across the hallway/intersection. A catapult launches an object across the hallway/intersection. An airtight tube consisting of paper towel tubes held together with duct tape rises across the hallway/intersection. A fan or hairdryer is used at one end of the tube to blow a ping-pong ball through the tube to the other side of the hallway/intersection. A racecar or marble runs down a ramp such as a Hot Wheels track and jumps across the hallway into a bucket on the other side, or the racecar or marble simply rolls across the floor to reach the other side of the hallway and trigger the next action. An air track is set up at an angle with a car resting on the top end, but the angle is not steep enough for the car to move. The air track turns on, becoming frictionless, making the car slide down the track and trigger the next action. A mass falls into a bucket resting on a scale/balance beam, which pushes up on the other side. This side is attached to a vertical yardstick, which lifts up when the bucket is depressed and triggers the next action a yard above the lifted end of the scale. A mass falls into a bucket that is suspended by a cable. The cable pulls something some distance above the bucket that triggers the next action. Both this and the previous idea could make use of the half-wall outside the door to Benedum 229. 4
Input Requirements (A sketch of these input requirements is presented on the following page.) A ball, between 40 and 100 grams in mass and no more than 2 inches in diameter (for reference, a golf ball is 46 grams and 1.68 inches in diameter), must be deposited in a bucket (which is included in segment 50). The bucket will have an inside diameter between 5 and 6.5 inches, a height between 4 and 6 inches, and a handle on top that will have roughly the same radius as the opening of the bucket. Before segment 50 is triggered, the bucket will be suspended by its handle from the top of the half wall located directly outside the door to Benedum 229. In this configuration, the rim of the bucket will be 7 inches above the ground, the central axis of the bucket will be between 2.5 and 3.5 inches away from the half wall, and the plane of the handle will be parallel to the wall the bucket is touching. The bucket will be touching the side of the half wall closest to room 229, and the distance between the point of contact between the bucket and right edge of the wall will be approximately 1 inch. To prevent the bucket from moving too much when the ball is deposited inside, the ball must contact the bucket at a speed no greater than 18 inches per second. Lastly, there must be no obstructions between the bucket and the ground so that the bucket is able to fall freely to the ground when the ball is deposited inside. 5
Sketch of Input Requirements 6
Output Requirements A ball of approximately 150 grams will fall a distance of 28 inches measured from the ground. The drop site should be lined directly under the spot where the railing on the far wall of the steps to the tutoring area meets the design zone for team 51, measured about 4-5 inches from the wall. The ball must fall straight down where it will land on a platform (provided by team 51) and roll off to start the next segment of the machine. 7
Preliminary Design Description To trigger the machine, weight will be added to a bucket suspended by a cable, as described in the input requirements. That weight (provided by team 49) will probably consist of a single golf ball or several marbles. That cable will be attached to a lever (e.g., a yardstick) whose fulcrum rests at some point on top of the half wall described in the problem statement. The other end of the lever will be attached to a counterweight such that the lever is tilted toward the side of the counterweight before the machine is initiated. When the weight is added to the bucket, the cable will pull that side of the lever and release a golf ball that was previously held in place by the side of the lever attached to the counterweight. The golf ball will travel down a V-shaped track toward the base of the wall and land in a small basket sitting on the switch on a surge protector, which will be plugged into the outlet in the tutoring area. A blow dryer will be plugged into the surge protector, and the cord of the blow dryer will run from the base of the half-wall back up to the top. The end of the blow dryer will be pointed upwards and will attach to a tube made of paper towel rolls connected with duct tape (or the tube might consist of some other accessible material). This tube will act as a bridge over the hallway and will be supported from the ground (e.g., with garbage cans, rakes, shovels, etc.). The tube/bridge will be high enough so that people can safely walk underneath it as they climb the stairs to the tutoring area. Before the blow dryer is turned on, a ping pong ball will be resting inside the tube on top of the blow dryer s end. A small door near the bottom of the tube will allow the ping pong ball to be placed easily inside during setup of the machine. When the switch on the surge protector is flipped and the blow dryer turns on, the ping pong ball will be blown to the top of the tube, where it will then roll/be blown to the other side of the hallway through the tube. When the ping pong ball reaches the far side of the hallway, it will fall through the tube and hit a golf ball (or a Hot Wheels car) that is resting in the horizontal end of the tube. The golf ball (or Hot Wheels car) will then roll down a track connected under the railing, gaining momentum. When the golf ball (or Hot Wheels car) reaches the end of the track, it will hit a baseball that will be balanced on a platform at the end of the track. The track will be pointed slightly upwards at the end, so the golf ball (or Hot Wheels car) will roll backwards after hitting the baseball and remain on the track. When hit, the baseball will be dropped off the platform and fall to the ground directly underneath the bottommost railing support (as specified by team 51), starting the next segment. 8
Top View of Complete Design 9
Sketch of Input Design 10
Sketch of Output Design 11
Note to reader: After further consideration of the preliminary design, it was determined that a more detailed plan of the PVC system was needed. The following sketch presents an intermediate version between the preliminary and final designs. Notable design changes include changing the position of the blow dryer (supported above the ground instead of on the table so that the ping pong ball does not have as far to travel upwards) and specifying the supports to used. In the sketch below, the left support is made from K nex, the center support is made from lumber and PVC, and the right support is made from the PVC itself. 12
Final Design Lever and Switch Mechanism 13
Blow Dryer and PVC System 14
Output System 15
Description Note to reader: The final design is in many ways the same or very similar to the preliminary design; that is, few changes needed to be made once the construction and testing stage began. The following is a brief summary of the final design. 1. Several marbles, provided by Group 49, fall into a bucket to start the machine segment. 2. That bucket is connected to one side of a lever, and the other side is attached to a stopper and counterweight that releases a golf ball when the lever is activated. 3. The golf ball, sitting on a short ramp on the edge of a table, is free to fall off the table into a cup when the stopper on the lever moves upward. 4. The force of the golf ball falling into the cup triggers the switch on a power strip via a system of paint sticks that transfers that force from the cup to the switch. 5. The power strip turns on a blow dryer raised four feet above the table that the golf ball rolled off of. 6. The blow dryer blows a ping pong ball through a PVC tube, up over the stairway and down the wall on the other side. 7. When the ping pong ball reaches the other end of the PVC tube, it hits a golf ball perched on the edge of a ramp. 8. The golf ball rolls down the ramp and knocks a baseball into Group 51 s segment. * No part of this design involved the use of any liquids, explosives, flames, or projectiles, and nothing was mounted to the walls or adhered to floors. Video The video of the machine segment can be found at this link: https://www.youtube.com/watch?v=ceejj9b-7si&feature=youtu.be 16
Bill of Materials Material Quantity Dimensions PVC pipe 3 10 ft x 1.5 in PVC short 90 degree elbow 1 1.5 in PVC long 90 degree elbow 2 1.5 in PVC 45 degree elbow 1 1.5 in PVC tee coupling 2 1.5 in PVC cap 1 1.5 in PVC male adapter 1 1.5 in lumber 2 2 x 4 screws 16 3 in cardboard cereal boxes 3 baseball 2 golf ball 2 Pitt ping pong ball 1 40 mm diameter blow dryer 1 paint sticks 3 12 in yardstick 1 36 in bucket 1 power strip 1 extension cords 2 bungee cord 1 2 ft clamp 1 2 in paper cup 1 17
Pink Pearl erasers 4 thumb tacks 12 rubber mat K nex masking tape string 2.5 square feet a lot a lot several feet staples 10-20 18