Chain & Sprocket
#25 and #35 chain, sprockets, even link counts, and why chain needs tensioning.
01
Chain & Sprocket
Chain carries big force over long distances, like a bike.
- #25 chain: 0.25 in pitch — strong and light, the FRC default.
- #35 chain: 0.375 in pitch — heavier, for high torque.
- Ratio = output sprocket teeth / input sprocket teeth.
FUSION 360 · SCREENSHOT
add → course-shots/1b-09/1.png
FIG 1
Chain Sizing
Measurements
- Pitch = link length
- Pitch length = pitch x links — keep it EVEN
- Clearance diameter = PD + pitch
Modeling
- AltSkripts Belt Generator handles chain too
- AltSkripts C-C Distance for sprocket spacing
- Origin reference first
Key idea
#25 for most things, #35 for heavy torque, even links always.
And plan for stretch.
Recap
CHAIN & SPROCKET
- #25 (0.25 in) default; #35 (0.375 in) heavy
- Keep link count even — no half-links
- Clearance dia = PD + pitch
- Chain stretches — tension 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.