Automaton

The goal of our project was to print out and assemble 2-D pieces in order to make our own 3D automaton. My partner and I designed an Osprey to move up and down while its propellers spun by using cams, followers, and a hand crank. Its dimensions are approximately 25 by 25 by 30cm. This device can be assembled in less than 10 easy steps and it’s a great tool to learn about the conversion of rotational motion into linear motion, normal force and frictional force, and more. Download this fun automaton and let your inner-child soar!

Team project partner: c47s

How I Designed This

At the very start of the design process, we had a few ideas including a car that rocked side to side, as if it were traveling on a bumpy road. The tires of the car would rest on two cams that would move up and down in sync with the hand crank. Next, we discussed using lines of gears to shift cars forward and backward on a road. Another idea we had was a helicopter with a rotating propeller. That design was the closest to our final design because they both had a driving shaft connected to several cams and followers and one of the cams was responsible for not only the linear motion up and down, but the rotation of the propeller. We settled for a design that consisted of a 3D Osprey with a driving shaft that held three cams, two that rotated the two propellers, and the last to move the Osprey up and down. From the first model to the second one, we learned a few things. First, to create the friction required to spin the propeller, we needed to put sandpaper on the two outside cams, not just on the two round follower plates. Also, in our second model, we realized that we could save filament by creating gaps in the box. Lastly, we corrected the size of our round follower plates by making them smaller. In the first version, the round plates extended outside the width of the box, so we added a rectangular window for the plate to move up and down. However, we miscalculated how large the window had to be in the first version, so the window was not big enough for the full range of motion of the round plate, which restricted the change in height of the osprey. Lastly, after we printed our second version, we realized that the bagel-shaped pieces that secured the driving shaft to the box were very helpful to hold the driving shaft from moving left to right, instead of relying on the sturdiness of the box by making the end of the rod thinner.

Parts List

1 Box Top

2 Box Sides

1 Box Bottom

1 Crank Handle

1 Crank Plate

1 Driving Shaft

3 Cams

1 Square Follower Plate

1 Square Follower Shaft

2 Round Follower Plates

2 Round Follower Shafts

1 Osprey

2 Propellers

Step one

Glue sandpaper to the bottom of the round follower shafts and the outside of two of the cams. Don’t make the same mistake as us — be sure to leave one cam without sandpaper glued to the outside rim.

1 =

Step two

Attach the round driving shafts to the round follower plates and the square follower shaft to the rectangular follower plate.

2 =

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Step three

Fit the shafts (with the plates attached) through the corresponding holes in the top piece of the box.

3 =

Step four

Place the Osprey on the follower shafts. The round ones should go through the two holes at the ends of its wings, and the square one should go up its center. Push the square shaft just far enough to be flush with the top of the Osprey.

4 =

Step five

Add the two propellers to the tops of the round follower shafts.

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Step six

Push the cams onto the drive shaft. Each should be secured by a square section. The cam that does not have sandpaper should be located on the middle square section of the shaft.

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Step seven

Assemble the box: Add the sides to the bottom, put in the drive shaft, and then add the top, with Osprey and followers attached.

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Step eight

Add the crank handle to the crank plate.

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Step nine

Attach the newly created crank to the peg protruding from the side of the drive shaft that sticks out of the box.

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