Globoid worm gearbox (20:1) with ball bearings (backdrivable)

This work is inspired by RollerDrive by Sankyo-Seisakusho.

BOM:

• 683 ball bearing (3x7x3) - 20 pcs
• 608 ball bearing (8x22x7)- 4 pcs
• M3x10 screw - 20 pcs
• M3 nut - 20 pcs
• M4x10 screw - 4 pcs
• M4 nut - 4 pcs

Driving the gearbox:

• by a hand
• by an electric motor (BLDC, stepper, DC, etc.):
  • there is a 6 mm hex shaft on the one end of worm
  • and 5 mm hole (with 4.5 mm flat) on the other side

GM3408H BLDC motor is used in the demo video.

The gearbox is back-drivable, please note that print quality is very important for this feature.

The design had been done completely in FreeCAD Part Design and Part workbenches (and Assembly3), without using any scripting. I used the LinkDaily branch.