Handheld 3:1/4:1 Planetary Gearbox

Design files for this project can be found hereParts have been designed to be 0.3mm larger. This should be taken taken into account when printing.

Here’s a gearbox that I made for testing purposes back when I was designing my improved filament extruder. Comprised of ten parts, this low-tolerance gearbox is spec’ed to have no backlash between the gears if properly printed. If the annular gear is held, the sun gear and carrier will rotate at a 4:1 ratio. If the carrier is held, the sun gear and annular gear will rotate at a 3:1 ratio. For more information on 3D printed gears and/or epicyclic (planetary) gearboxes, see the bottom of my post on the NEMA 17 gearbox project page.

Additional Parts

  • 3x 10mm M3 Bolts
  • 4x 16mm M3 Bolts
  • 7x M3 Nuts

Printing and Assembly Notes

  • 100% infill may cause parts to be too big, resulting in increased friction between parts
  • Layer height of 100 micron and print speeds of less than 50 mm/s is recommended
  • Batch printing all pieces at once is NOT recommended
  • Teflon lubrication should be applied between all moving parts
  • Retraction MUST be enabled for gears to be properly printed
  • Using my custom filament extruder and fan mount will result in higher quality prints
  • Simplify3D (v2.2.0) was used to slice the model for printing
    • My custom UM2 profile can be downloaded here
    • Other slicing engines may result in non-ideal prints!
  • Gears may be difficult to turn when first assembled, it takes a bit of time to break it in
  • Assembly is fairly easy and is left as an exercise to the reader