Final Project--The building begins!

With our general goals in mind, we set to work building a model of our robot out of Lego.

Clara and I decided to divide and conquer, so she focused on trying to figure out the best popping mechanism for stage two while I focused on figuring out how to build a creep elevator for stage one.

After thinking about potential pully or cam mechanisms, Lyn showed us the wonder that is the linear gear, and we decided the best way to elevate our creep would be by using the linear gears and a gear train.

An early sketch with possible elevation ideas

Gear train preliminary sketch.. the caption is very necessary in this case.

As you might (or might not) be able to see from my scribbled notes, we were not sure if the gear train would have enough torque to lift the creep's platform.  The only way to find out was to build it and see, so we set to work.

I built this primary structure, then started working on the gear trains.  It took a while to figure out the correct gear ratio.  We needed a gear train that would allow for slow elevation without having too much torque. (We didn't want our creep to elevate too fast, since that would make him lose some of his creepiness.) Here is the process:

Linear gear track

Close up: Linear gears!

We started with mini gear trains..

Two mini gear trains

Attached them to the motor...

Put it all in a Lego box...

And tried out the structure for size!

The linear gear idea seemed like it would work, so it was time to go big and build a full-sized gear train:

Linear gear posts--one for each corner of our elevator-to-be

One of two gear trains

After attaching a motor between the two gear trains,  and a Lego bottom and top, our initial stage one mechanism was complete! Here are the gear trains in action (with the top of the Lego box removed):

Finally, after much trail and error and with fingers that had been slightly mangled by too much gear handling, it was time to test out the elevator!

In case you can't tell by my squeals of excitement, it worked!  We put a textbook on top to simulate the weight the elevator would need to carry, and it did a great job.

As you can see the four linear gear posts require a great amount of stabilization.  We planned to connect them to the sides of our creep box, which would require the box to have very accurate proportions.

Now that stage one existed, it was time to figure out how to connect it to stage two. 

After experimenting with various ratchet and spool mechanisms, Clara had the idea to use a scissor-like mechanism to lift our creep head.  She whipped up a lego version, and we attached it to the stage one base.  We were both very excited about this idea, because it seemed much simpler and more plausible than our previous stage two mechanism ideas had been.

Experimenting with ratchet idea

Scissor mechanism!

The scissor mechanism is connected to the motor on the right by two more of the same sort of pieces it is made out of--one the same size (lying flat on the top), and one slightly shorter (connected to the motor).  When the motor rotates, it causes a forward motion, which in turn activates the scissors.  The piece lying flat on the top is forced to go only in a forward motion, instead of possible up/down or side to side motion, by the little Lego stabilization box above.

We then tested the mechanism out with the motor, to see if it would work.

As you can see the mechanism worked, but lacked much stability.  We were not able to stabilize it using Lego, but planned to build our delrin structure so that it would be able to stabilize everything.  Additionally, we decided to double the scissor mechanism to give it some more power and stability.  We planned to attach the head to spring on top of a small (and very light) platform on the top of the scissor mechanisms.