OpenSCAD BOSL2 Involute Gear Pair example
Advanced geometry
Lesson 22 of 22
Use actual involute gears with matching tooth module, calculated center distance, and the correct rotation ratio.
Try changing:
driver_teethdriven_teethtooth_moduledriver_anglethicknessshaft_diameterbacklashHigh compile complexity. Loads bundled BOSL2 and constructs involute profiles; use draft quality while changing counts.
How this model works
BOSL2's spur_gear constructs real involute teeth, not decorative radial blocks. Both gears use the same module and 20-degree pressure angle. With profile_shift explicitly zero and at least 18 teeth, their center distance is module times the sum of tooth counts divided by two; gear_dist computes that placement. BOSL2 places a tooth on positive Y, so the rotations align one driver's tooth with a driven gap on the line of centers. The driven angle changes by minus driver_angle times driver_teeth / driven_teeth. Backlash reduces tooth thickness for running clearance, but does not certify fit, durability, lubrication, or load capacity. The gears are separate parts with no supporting shafts or bearings.
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Make it your own
Set 20 driver teeth and 40 driven teeth. Advance driver_angle by 60 degrees and verify the driven gear moves 30 degrees in the opposite direction. Keep tooth_module and pressure angle common to both gears, and test a small printed pair before choosing working clearances.
Change one parameter at a time and inspect the result. Use the workspace reset action to return to this lesson’s original model.
