Imagineering

In my junior year engineering class we read a book called 'Is There an Engineer Inside You?"  (yeah there is cuz I ate one. haha.) Up until this point, all I really knew was that I liked art and science and design things that are cool and pretty and that I LOVE Disney. While reading this book, all my interests magically came together when I discovered a field call Imagineering. Imagineering is combination of 'imagination' and 'engineering', a word coined by Walt Disney. Imagineers are engineers, architects, landscape designers, master planners, and artists. I think it would be super awesome to work for Disney and design themes parks and resorts. 

So as I was scouring the internet for cool ways to learn more about imagineering, I found some awesome blogs (that I may talk about later) and some books that I wanted get. And then I remembered that Wellesley has a library! With books! (duh) I searched through the cataloge for Imagineering or Disney and found a few books. This is one is Animated Architecture by Derek Walker. I found so much interesting thing in this book at every few minutes I found my self interrupting my room mate's studying to say "Hey did you know...!" I realized that I kinda wanted to write this stuff down. So I took notes. On a book. That wasn't assigned. But its such a cool book! Its essentially (so far) about the designing of EPCOT and what Walt Disney wanted it to become.

Original 1980's Rendering of the Epcot Center

Lego Car

We began by playing with our lego car and today we really began to focus. We had a preliminary set up for our car that looked like this:

We used the big red gear to reduce the speed quickly. This would also increase torque. Using one big gear instead of more little gears would eliminate unnecessary friction. The only problem with the big gear is that we have to maneuver our axles. As you can see, we have a mini axle to the right so that the gears though but don't interfere. We timed this across the table with out the weight and it came out to about 11 seconds for one yard- pretty slow. I think it had a 1:81 ratio. 

In our next iteration we got rid of the red gear. We tried putting the gears at an angle (instead of only putting axles on a horizontal plane moving them up and down) but it didn't really work. We also tried to keep the car balanced by having the axles run all the way across. This would better support the gears and prevent them from wiggling.  This one was able to go one yard in about 6 seconds, so that was quite an improvement. 
This design has a 1:27 reduction ratio and was our final design. It took about 8-10 seconds to run the course with the weight. After completing this we experimented. We tried reducing the gears more by adding another 1:3 ration to the end of the gear box. This slowed our car down by about a second and a half. 

Final Car:

Wrap up:

The higher gear ratios (smaller numbers along the y axis) (probably not the best way to graph this but...)  tended to have higher times.

Eve found her Wall-E!

Mechanism

Converting Rotational motion to Linear Motion
(after looking at the videos, I'm pretty sure the Boston Museum of Science has a whole wall of these mechanisms...)

Slotted Connecting Rod
These are what are on elliptical machines. The rod moves in and out and linear-ish and while the little nob part moves in a circle. 


Reciprocating Rectilinear Motion
The bar at the bottom goes back and forth (linear). A perpendicular piece rocks side to side. That connects to a nub on the circular gear. It seems to slow down at the top and speed up at the bottom of the gear's motion. 

Rotary into Rectilinear Motion
This one is pretty cool because it looks like the components are playing game or they are in an assembly line or something. In the top, 2 nubs are attached to the circle and they spin. The hit the prongs coming out of the other parts and knock them away. 
In the bottom one, the triangle spins in the center and the prongs hit the corners of the surrounding piece moving it from side to side. This moves the whole axis left and right.

Learning About Gears

Today in class began learning about mechanisms with a focus on gears. 

So we are going to be mainly working with gears

So say you have a gear with 8 teeth and a gear with 24 gears. For every one turn of the 8 tooth gear, the 24 gear turns 1/3 of the total distance. 

Another thing to take into consideration is friction- the more gears in a gear box the more friction that that will be created. 

Windlass Part 2

So Anya and I had our windlass design essentially finalized. We started by constructing a cardboard model to test how pieces would fit together. Everything looked good and we got the design approved to we moved on to drawing out our designs on SolidWorks. 

After finishing all the pieces and assembling them, we had it checked by the professors. We realized (we their help) that the washers that we had hoped would fit snuggly would probably fall out. We designed a couple versions of these exterior 'washers' that would keep the rotating interior piece from falling out. At first it was a larger circle to cover the inner one, but then we made a C-clip shaped one to save material (also it was easier to piano wire later). We also added the hole and 2 little prongs on each side of the spool to guide the string. 

Evolution of the Spool 

Here we widened the spool after realizing it wouldn't be able 

to span the table with hthese

  These are the pieces that were heavily reliant on the thickness of the delrin (4.970 mm). The tight fit is what would have held them together

 Interior Washer

We ended up keeping the notch part that would be cut out as scrap from the delrin as a 

plug to keep the spool in place.

 All our original pieces

 Attempting to fit in the clip

Finally we were ready to print. We sent and out pieces to the laser print, printed them, and assembled. We noticed that the pieces were not fitting properly  the base was wobbly and didn't fit properly with the other pieces. We check the delrin and realized that it our pieces were printed on the wrong thickness. We realized that part of this problem was also that the notches were long enough and that was part of the wobbling- the top part of the base could not reach the table. In order to conserve material, we adjusted the length of the notch on only the bottom base piece. We reprinted the parts that we need- some parts such as the base took into account the thickness but other such as the spool were independent of the thickness of the delrin. We put the Windlass together (without fastenings  to make sure everything fit. At this point we wrapped of the day but returned later to finish. All we really had to do was piano wire the clips to each other through the washer. (Ideally this would have been a magical tight fit but the laser cutter melts a certain amount of the plastic and we would have to experiment with sizing and such.)

And the we were finished! We tested it out and it worked! Anya took a video on her phone as proof that it worked. We were a little worried about the spool- it started to bend a tiny bit, and then more and more after each test so we left it alone. In our original plan we did say we wanted to double layer the spool, but we saw it as unnecessary at this point and it would have wasted material. Another problem was that the spool moves in and out so the handle sometimes hits the base piece. We did think about this happening and tried to avoid it but I guess our calculations weren't perfect. The other change I would have made was to add a horizontal base. Our windlass has essentially 3 major components that move independently from each other, so it wobbled a lot as we cranked it. I would have connected the to base pieces in some way that would keep them grounded but not get in the way of the bottle.

In the end our windlass worked and I am very happy with out design!