Tutorials and resources for 3D printing and 3D modeling enthusiasts

# Instant Straight & Helical Gear Calculator

This calculator allows you to create a pair of perfectly meshing involute gears instantly! Enter your standard gear parameters (module, number of teeth, profile shifts), press a button, copy and paste the generated Python script to Blender, and your two gear outlines are ready! Turning them into full-bodied straight, helical or herringbone gears is a piece of cake. The calculator will also check the generated outlines for overlaps, and advise you to use a positive profile shift if an overlap does occur.

The outlines of two meshing involute gears can be fully defined by the number of teeth on both gears, module, profile shift and pressure angle. A positive profile shift is required for the gears with 18 teeth or fewer to avoid an overlap with the outline of the other gear. If the specified profile shift is insufficient, the calculator displays a warning.

The calculator generates a Python script that creates both gear outlines based on the aforementioned parameters.

For a helical gear, the desired Helix Angle (β) and Gear Width (W) must also be specified for the calculator to compute the twist angles for both gears. These angles can be used with Blender's Simple Deform modifier (Twist) to instantly turn straight gears into helical (or herringbone) ones.

The optional Extra Tip Vertex Position parameter (v), if set to a non-zero value, creates an extra vertex on each side of all the teeth close to the tooth tip, as shown below. This allows the Subdivision Surface modifier to be applied to the gears while preserving the geometry of the tooth. Without this extra vertex, the modifier makes the tooth tips too rounded. The closer this value to 1, the closer the extra vertex is to the tooth tip. Normally, a value between 0.9 and 0.99 should be used.

 v = 0 v = 0.9

Basic Dimensions
ParameterSymbolGear 1Gear 2
Modulem
Pressure Angle (°)α
Number of Teethz
Profile Shiftx
Helix Angle (°)β
Gear WidthW
Extra Tip Vertex Positionv
Twist angle (°)φ
Blender 2.8+