Gear Ratios

Subject Area: Technology, Engineering, Math

Learning Objectives: Students will be able to create a drivetrain and calculate the gear ratio.

Materials Needed: One computer, one Micro or Micro+ 3D printer, and one 250ft PLA 3D Ink filament spool per 2-5 students.

Brief Description: Students will print a platform, a crank, and a variety of gears. The gears are each labeled with their diameter. The Students can create a unique drivetrain and calculate the gear ratio.

To Prepare: Students will need a computer that has the M3D software on it. We recommend one printer per every 2-5 students. The Micro or Micro+ 3D printer will need to be plugged into both the wall and the computer. Each printer will need to have a 250ft spool of PLA feeding into the external port. A spool holder is also recommended.

If you need assistance with any of the above please see our guides at

Lesson Plan:

1. Students will go online to: and download the gear ratio models. 2. Students will open the M3D Software on a computer, upload the models, and print: 2 of each of the 4 gear sizes, 8 pegs, a crank, and the gear box board. 3. Once the models have printed, students should create a drivetrain by putting the gears onto the gear box. 4. After they have their drivetrain, students should measure the RPM of the last gear, the torque of the system, and the gear ratio.

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