Gear Basics
Gear ratios, diametral pitch, pitch diameter, and the center-to-center math that makes gears actually mesh.
01
How Gears Work
Meshing teeth pass motion between shafts.
- Different tooth counts change speed and torque.
- Gears only mesh if they share a tooth profile (same DP).
- The FRC standard is 20 DP.
FUSION 360 · SCREENSHOT
add → course-shots/1b-05/1.png
FIG 1
The Gear Math
Ratio & PD
- Ratio = driven teeth / driver teeth
- PD = teeth / DP (DP = 20)
- 7:1 = 7x torque, 1/7 speed
Spacing
- C2C = 0.5*PD1 + 0.5*PD2
- Constrain PD circles tangent to space them
- Use AltSkripts C-C Distance to check
Key idea
Constrain the pitch-diameter circles tangent and the gears mesh.
Space by PD, not by guessing.
Recap
GEAR BASICS
- Ratio = driven / driver; PD = teeth / DP (20)
- C2C = half PD1 + half PD2
- PD circles tangent = proper mesh
- Even gears flip direction, odd keep it
Your Task
Build this
- Model what this lesson covers in Fusion 360.
- Use the AltSkripts tools where they apply.
- Save it with a clear name.
How to submit
- In Fusion: Share → Public Link → Copy.
- Paste the link below.
- A coach reviews it in AltHub.