Involute Gear

Involute Gear makes spur gears, racks and internal (ring) gears with true involute teeth, as a solid or as a flat 2D outline. Gears mesh correctly with other gears of the same Circular Pitch and Pressure Angle.

mechanical_gears

How to Use

  1. Open Included > Mechanical in the Library (or under Add to Bed) and add Involute Gear to the bed
  2. Choose the Gear Type and set the Tooth Count
  3. Set the Circular Pitch, which sets the size of the teeth (and so of the gear)

Parameters

  • Plane - The construction plane the gear is drawn on (default XY, flat on the bed)
  • Output - 3D (default) makes a solid gear; 2D makes its flat outline

Features

  • Gear Type - External (default, an ordinary gear with teeth on the outside), Rack (a straight bar with teeth) or Internal (a ring with teeth on the inside, for a smaller gear to run in)
  • Height - How thick the gear is, in mm (default 5). Shown only for 3D output
  • Tooth Count - Number of teeth (default 30; the slider runs 4 to 60)
  • Circular Pitch - The distance from one tooth to the next along the pitch circle: its circumference divided by the number of teeth, in mm (default 8; the slider runs 3 to 30). It sets the size of the teeth and so of the gear
  • Center Hole Diameter - The diameter of the shaft hole, in mm (default 4; 0 for no hole). External gears only
  • Outer Edge Width - Internal gears only. How wide the ring outside the teeth is, in mm (default 4)
  • Inner Gear Tooth Count - Internal gears only. The tooth count of the gear that will run inside (default 8), needed to cut the inside teeth correctly. It must be at least 4 less than Tooth Count

Advanced

  • Pressure Angle - The angle of the tooth contact surface, in degrees (default 20; common values are 14.5, 20 and 25). All meshing gears must use the same pressure angle
  • Clearance - The smallest gap between the tip of a tooth and the bottom of the space it meshes into, in mm (default 0.05)
  • Backlash - The smallest gap between meshing teeth, in mm (default 0.05)

Gear Data (Read Only)

Not shown for a Rack.

  • Pitch Radius - The radius where gears mesh with each other
  • Outer Diameter - The diameter to the tips of the teeth

Tips

  • Two gears will mesh correctly when they have the same Circular Pitch and Pressure Angle
  • Use the Pitch Radius values to correctly space meshing gears – the distance between gear centers should equal the sum of their pitch radii
  • Raise Backlash if meshing gears are too tight to turn freely
  • For a flat gear profile to use with path operations such as Linear Extrude, set Output to 2D
  • Cycloidal Gear - A cycloidal speed reducer, for large reductions in one compact stage
  • Threads - Create threaded features