# Engineering Projects/StrandBeest/Howard Community College/fall2012/p2-550-SO

### Problem Statement

Build a crankshaft that allows the movement of a StrandBeest legs.

### Story

From all the information gathered from past projects we considered the building of a crankshaft as maximum priority for the beginning of this project. We watched videos and read information on how to build a crankshafts and the mechanism involving the legs of a strandbeest in order to understand their interaction for a successful reproduction of the system. When using the LEGO pieces to build the crankshaft, as the pieces are fixed at 90 degrees only 180 degrees sections of the crankshaft were able to be built. Since with the original size of the pieces used the crankshaft had too much extra space in between the pieces to hold the legs, we decided to place the pieces closer together and cut the parts that would affect the mobility of the design. After fixing the design flaws to the crankshaft with sections at 180 degrees, we, once again, read about the mechanism of stranbeest, but with a major focus on the function and maneuver of crankshaft in the system. As a result of all the collected information, we concluded that each crankshaft section must be located at a 120 degrees form the other in order for the strandbeest be able to walk. Since the manufactured produced LEGOs used for this design come set at 180 degrees, we decided to use other LEGO pieces, which rather than attaching to the one another we just simply can glue together using the help of hot glue. In the building of this second crankshaft we will be using some smaller pieces from those used in the first built crankshaft, as a way to decrease weight and stress to the legs of the strandbeest. Thus far we have decided to use prototype straw legs in order to do preliminary testing for the strandbeest. The final material to use in this project may or may not vary depending on the results from preliminary findings. In case that more weight is needed to be added to the straw less to release it's stress from the weight of the crankshaft, we figured that we could add some powdery substance, such as sand or flour, and seal the ends with hot glue. First however, the straw legs will be build without any addition of other materials. During this week we built a prototype crankshaft of the form and structure of the crankshaft to be build. This prototype served as a method for understanding the placement and position of the crankshaft pieces. After analyzing the reason as to why the crankshaft wouldn't work we realized that the pieces we use were straight pieces, therefore when moved at different angles their center will change with the piece. What we did was to link two LEGO pieces together and set them at 120 degrees, like this allowing the addition of a third piece without changing the center of the crankshaft. While looking for other pieces we came across a new piece that we haven't seen before and we believe it would be very beneficial in reducing the general weight of the crankshaft.

### Decision List

1. Gather information on crankshaft and strandBeest 1 2 3

2. Read tutorials from past projects on strandBeest 1 2 3 4

3. Investigate the working mechanisms of strandBeests 1 2 3 and crankshafts 1

4. Build a crankshaft made out of LEGO pieces 1

5. Test the crankshaft for work-ability and flaws in the design

6. Make the necessary repairs to the design

7. Determine a material to use for the legs of strandbeest

8. Closely analyze the mechanism of a strandbeest leg system 1 2 3 4 to determine the possibility of movement for an strandbeest with a crankshaft 180 degrees between sections

9. Redesign the crankshaft system to 120 degrees angles

10. Select the LEGO pieces going to be use in the rebuild of the crankshaft

11. Compile data on the different types of materials to use to build the legs of a strandbeest 1 2 3 4 5 6 7

12. Use LEGO piece to build a crankshaft of sections at 120 degrees

13. Build prototype strandbeest legs to test the crankshaft

14. Test the newly build crankshaft

15. Create a tutorial for building a crankshaft

### Material List

Crankshaft: LEGO pieces

StrandBeest Legs: Straws

N/A

### Time

Hours Per Week:

Team Work: ~ 2 hr/week (In Class), ~ 2 hr/week (Out Side Class)

Individual Work: ~ 4 hr/week (Out Side Class)

After 4 Weeks:

Total Team Work Hours: ~16 hr/4 week

Individual Hours: ~ 16 hr/4 week

3 Individuals Hours: 48 hr/4 week

Accumulated Project Hours: ~64 hr/ 4 week

### Tutorials

How to Build a Crankshaft Made of LEGO Pieces

180 Degrees

1. Select the LEGO pieces to be use in the building of the crankshaft

2. Put the pieces together accordingly to the section they are from

Ends of Crankshaft

Sections of Crankshaft

3. Connect all the sections respectively

4. Tighten the crankshaft and cut the additional pieces of materials

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120 Degrees

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### Next Steps

1. Build prototype straw legs to test the work-ability of the crankshaft

2. Select a material to make the strandbeest legs of that will withstand the weight of the crankshaft without bending