PLANETARY GEAR SYSTEMS

Fall 2019 - Spring 2020

I have always been fascinated with planetary gear systems, so in the summer of 2019, decided to try to make some on my own. I used Creo family tables along with equation-driven curves to create a single gear part that could be quickly and seamlessly translated into many various gear parts. I then used different instances of the family table parts to create my own systems. As an example, all of the gears are different instances of the same generic part with varying gear properties and the internal cut features toggled on or off. In order to develop multiple planetary gear systems, I also modeled a family table of cages to hold the model together along with a family table of supports (spinners) to synchronize the movement of multiple levels of gears. This is used in my open system design

 
 

Open Gear System

I first developed the above open planetary gear system. This system includes four different size gears with the geometry inherited from the common generic part. It also includes a transfer mechanism (spinner) to translate the motion of the first level to the second level and carry on the gear ratio. I experimented with different pressure angles and gear pitch diameters and trimmed a tiny bit of material from the outer perimeter to account for excess 3D printing filament being deposited. The gear geometry is all driven from involute gear equations as discussed above.

 

Planetary Gear Coaster - Small

With the test assembly completed and functional, I decided during the first couple weeks of Coronavirus to spend a weekend translating my theoretical design into something functional. I created two variations of the design, using family tables that would be able to hold either small coffee cups or much larger glasses and bowls. These new designs used different pressure angles to eliminate sharp corners in the gear teeth.

As mentioned above, all of the gears are driven from the same generic part with different values given for the pressure angle, the diameter, and the interior features turned on or off depending on the desired result. Additionally, the cuts in the body are relation-driven and have the same generic part. Many of these similarities are evident with close examination of the parts.

 

Planetary Gear Coaster - Large

This second variation of the planetary gear system coaster is similar in many aspects. Instead of just being a larger print, however, this system uses a different pitch and pressure angle, allowing for fewer teeth on the larger design. There is added clearance in the design of the teeth to account for some extra material in the 3D Printing process. Though this resulted in a less precise mesh, it still spins nicely

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©2020 by Trevor Henningson