Planetary Gear Generator

Spur, helical and herringbone planetary gearboxes with carrier and housing, exported as millimetre SVG, DXF and STL, or built directly in Fusion 360.

English
Teeth
Find teeth for a ratio
    Stacked stages

    Each stage's carrier drives the next stage's sun, so the ratios multiply (4 × 4 × 4 = 64:1). All stages share the module and the ring, so the housing keeps one diameter.

    0 = same as stage 1. Each stage's planets get (Zr − Zs) / 2 teeth, so Zr − Zs must be even.

    High-ratio stage

    Stepped planets drive a second ring with a few more teeth. The ring is held, the sun drives, and the second ring is the output, for 30–300:1 in one stage.

    0 = automatic (Zp2 = Zp, Zr2 = Zr + N). Stage 2 takes its module from the shared centre distance and is always spur.

    Tooth form

    Planets and ring get x = −xs, so the centre distance stays standard.

    Advanced
    Helix & thickness

    β = 0 gives spur gears. Module is measured in the face plane.

    Bores

    D-flat is 10 % of Ø deep. Keyway follows DIN 6885. Hex is measured across flats.

    Carrier
    Ring & housing

    The ring is taller than the gears by the carrier thickness, so the carrier turns inside it and the cover bolts to its underside.

    Hold

    Key dimensions

    Ratios

    Design checks

      Export

      Everything SVG, DXF and STL for every part, the Fusion 360 data file and script, in one .zip.

      Build it in Fusion 360
      1. Script (full 3D): unzip, then in Fusion open Utilities → Add-Ins → Scripts and Add-Ins, click + next to My Scripts and choose the fusion/PlanetaryGears folder. Run it and pick the .json file. It builds every part as a solid body (helical and herringbone teeth included) and places the parts in mesh.
      2. SVG: Insert → Insert SVG on a sketch plane. The drawing is in millimetres, 1 unit = 1 mm, and the gear centre is the centre of the page.
      3. DXF: Insert → Insert DXF with units set to millimetres. Every arc is exact.
      4. Check the tip diameter in the sketch against the table above, then extrude. Bores and bolt holes are inner loops, so they cut through automatically.
      5. STL: each part sits on z = 0, ready to slice. The assembly STL shows the whole gearbox.