Herringbone gear train

A line of meshing chevron gears — the thrust-free gear train.

This is the chevron sibling of the gear train: a line of herringbone gears, each two opposite-hand helical halves so its axial thrust cancels, spaced at the correct centre distance so the train meshes. The chevron hand alternates down the train (external helicals only mesh opposite-hand), and each gear is phased so the teeth interlock while staying a separate printable body.

Find teeth for a ratio works here as on the gear train: it proposes tooth lists for the ratio you type, checks each for printing at this train’s own settings, and Apply writes one into the teeth as a single step.

1. Open the Generate panel from the left sidebar and choose Herringbone train (under Gears & drives).
2. The chevron gears drop in spaced to mesh. The parameters open in the Properties panel, where you set them.
3. Enter the tooth count of each gear, in mesh order (two or more).
4. Set the shared module, pressure angle, helix angle, thickness, and bore.
5. To get a particular ratio, open Find teeth for a ratio under the parameters, type the ratio (or an input and output speed), and Apply one of the tooth lists it proposes. Undo puts the old teeth back.