Projects / Gear Ratio Lab
Gear Ratio Lab
Build a laser-cut 3mm birch plywood gear train with measurable torque / speed tradeoff: count teeth, compute ratio, drive with a hand crank or low-RPM motor, and lift a known mass on a drum.
$7 Mechanisms
Digital guide + cut files + BOM + code · Parts sourced separately · Ages 8–14 with adult help
GearsInvolute spur gears, m 2, 20° (15/30/45T)
Structure3mm birch frame
ExperimentMass lift / tach
Build time3–6 hours
Skill levelIntermediate
Ages8+
Pack contents
- True involute 15/30/45T gears, frame with simple, idler and compound (i = 9) layouts, drum SVGs
- Mesh + experiment protocol guide
- First-principles: ratio, torque, module/pitch
- Optional tach sketch
- Verified BOM (~$16–71 hardware)
Typical hardware cost
Default structure is laser-cut birch plywood with real fasteners and hobby electronics you can source—honest BOM, not mystery modules.
- ~$16–71 in typical parts (makerspace cut toward the low end; mail-order toward the high end)
- Digital pack price ≠ hardware
The $7 pack is the digital guide + cut files + BOM + lessons + code, plus printable Builder's Corner build journal pages. Hardware is sourced separately — see Where to get kit materials. Buy with Stripe is live below.
Questions? Email us at lance.haney@gmail.com.
Pricing
- Home / Personal license $7
- Classroom license $29 — 1 teacher, up to 30 studentsOne $29 Classroom license covers one group of up to 30 students. Each additional group needs another license.
- Build materials available at cost + 10% — email for a quote
Learning outcomes
- Compute gear ratio from tooth counts
- Predict ideal ω and τ relationships
- Assemble a simple pair, an idler train and a true compound train (i = 9) on fixed centres
- Discuss friction, backlash, and ideal ≠ measured