Subsystem Overview Structure
With three other students, we designed and built a mechanical structure depicting a man looking for the Loch Ness Monster in the Scottish Highlands. Designed in SolidWorks, we achieved the motion of a man in search of the disappearing Loch Ness Monster. We utilized a four bar linkage, cam and cam follower, and gearbox complete with bevel gears and pulleys.
The structure contains a few subassemblies and components to the sculpture. Below is a plywood base cut from ShopBot. At the top of the plywood base is the gearbox powered by a motor hidden inside the base. The gear box has pieces made from a mill and lathe, while other parts such as the boat and the Loch Ness Monster are 3D printed. |
Personal Contribution
For this project, my SolidWorks design contributions were:
- boat and cam follower
- mounting brackets for the boat and finishing touches of the waves
- binoculars for the man (before switching to a spyglass)
- L brackets for the four bar linkage
- machined the clock-cage posts using a lathe
- drilled 1/64" holes in shafts for spring pins using a mill
- 3D printed and fit boat
- sheet metal L brackets
- helped assemble gearbox
Base
Gearbox
Above is the gearbox complete with plastic gears, bevel gears, and belts and pulleys. There are four gears, two pulleys, one belt, and a set of two bevel gears. The gearbox transfers power across our sculpture to the man and boat, and Loch Ness monster. The gearbox is made of two clock-cage plates held with five lathed aluminum clock-cage posts. The bottom of the gearbox contains two pulleys connected by a belt in our final assembly. A motor is attached to a shaft behind the pulley on the left, and as the motor spins, spins both the shafts on the right and the left. The shaft on the right connects to a set of bevel gears and rotate the motion from the horizontal direction to the vertical direction which power Nessie.
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Four Bar Linkage
On one side of the U frame is the second of the set of bevel gears which allows the shaft to turn the four bar linkage. On the other side of the frame is the four bar linkage, which sticks into and supports the weight of Nessie. The four bar linkage is laser cut out of delrin and assembled on D-shafts. The first image with the four bar is our initial design with a U shaped frame. However, the sheet metal had trouble bending at a 90 degree angle with the small distance between so we designed a frame consisting of two L brackets. This provided the 90 degree angle needed for the shafts to pass through both sides of the frame parallel to the bottom of the frame.
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Cam and Cam Follower
One the long aluminum rod from the gear box sits the cam. The objective of the cam is to for the cam follower to slowly raise and lower the boat as it follows the rotating cam producing a rocking movement, giving the illusion of a boat in calm waters. Our cam is a milled piece with a 1.7 inch diameter. From the top view, you can see the cam has a through cut of two different sized circles. The larger circle, 0.6 inch diameter, allows an adaptor to sit in the cam that connects to a D-shaft running through the smaller circle with a diameter of 0.25 inches.
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