Gear Generator App – Basic User Guide

Table of Content

What this app does?

This is a browser-based gear generator for involute gears. You can create:
  • External (spur/helical) gears
  • Internal gears
  • Racks
  • The app provides:
  • 2D profile preview (SVG)
  • Optional 3D preview
  • Exports: DXF (2D profile) and STEP (3D solid)
  • Note: STEP download requires access to the Premium version
Gear Generator

Gear Generator App UI

Involute Gear. Source: Wikipedia

What are involute gears?

An involute gear has tooth flanks shaped as an involute of a circle (the curve traced
by unwinding a taut string from a base circle). This geometry is popular because:

  • It’s tolerant of small center-distance errors while still transmitting motion smoothly.
  • It provides a (mostly) constant velocity ratio during meshing.
  • Standard tooling and design rules exist (module, pressure angle, addendum/dedendum, etc.).
  • Key circles you’ll see referenced:
  • Pitch circle (reference circle): where gears “theoretically” roll without slip.
  • Base circle: the circle the involute is generated from.
  • Tip (addendum) circle: outermost tooth tops.
  • Root (dedendum) circle: bottom of tooth spaces.
Gear Generator

Quick start

  • Choose the gear type: External Gear, Rack, or Internal Gear.
  • Set Teeth Count and Module.
  • Choose a Pressure Angle (20° is the most common default).
  • (Optional) Open Advanced Parameters for backlash/clearance/profile shift/hole.
  • Toggle 2D / 3D if you want a solid preview.
  • Export:
  • DXF for the 2D tooth profile
  • STEP for the 3D solid (uses Thickness, and Helix settings if applicable)
Gear Generator

Gear Generator App quick start

Reading the on-screen output

  • The app displays three computed diameters (when relevant):
  • Reference Diameter: pitch diameter (external/internal gears).
  • Tip Diameter: outside diameter (external) or inside tooth-top diameter (internal).
  • Root Diameter: root diameter (external) or inner root diameter (internal).
  • For racks, these are shown as N/A.
  • Tip: Hover over the question marks to preview the dimensions

UI controls and what each parameter means

Gear type selector

  • External Gear: standard gear where teeth point outward.
  • Internal Gear: ring gear where teeth point inward.
  • Rack: a straight gear (effectively an infinite-radius gear).
  • Notes:
  • For Internal Gear, the app enforces a higher minimum tooth count (to avoid invalid geometry).
  • For Rack, a center hole is not used.

View toggle

  • 2D / 3D toggle: switches between the 2D profile and a 3D solid preview.

Teeth Count

  • Teeth Count (integer): number of teeth on the gear.
  • Higher tooth count increases pitch diameter for a fixed module.
  • Very low tooth counts can undercut (depends on pressure angle and profile shift).

Module

  • Module (m) (mm/tooth): sets the overall tooth size.
  • Relationship (standard): pitch diameter d = m · z
  • Related quantity: circular pitch p = π · m
  • Practical meaning:
  • Bigger module → thicker teeth and larger gear for the same tooth count.

Pressure Angle

  • Pressure Angle (α) (degrees): the standard values are 14.5°, 20°, 25°.
  • Practical meaning:
  • Higher pressure angle generally increases tooth strength but increases radial forces.
  • 20° is the most common modern standard.

Thickness

  • Thickness (mm): the extrusion thickness used for 3D preview and STEP export.

Helix Angle

  • Helix Angle (degrees):
  • 0° → spur gear
  • > 0° → helical gear
  • Practical meaning:
  • Helical gears mesh more gradually (often smoother/quieter) but create axial thrust.

Helix Hand

  • Helix Hand (Left / Right): direction of the helix twist.
  • Practical meaning:
  • A mating helical gear typically uses the opposite hand (unless using crossed/helical arrangements).

Advanced Parameters

  • Open the Advanced Parameters section to access:

Backlash

  • Backlash (mm): intentional “gap” between mating tooth flanks.
  • Practical meaning:
  • Helps avoid binding from manufacturing tolerances, deflection, thermal expansion, etc.
  • Too much backlash increases play and positional error.

Clearance

  • Clearance (mm): extra space between the tip of one tooth and the root of the mating gear.
  • Practical meaning:
  • Prevents tip-root interference.
  • Commonly related to module in standard systems; the app limits extreme values.

Profile Shift

  • Profile Shift (x) (unitless, in fractions of module): shifts the tooth profile radially.
  • Practical meaning:
  • Can reduce undercut on low tooth counts, change tooth thickness at the pitch circle, and adjust center distance when used as a pair.
  • Positive shift generally increases tip/root radii (effect depends on gear type and conventions).

Center Hole Diameter

  • Center Hole Diameter (mm): diameter of the bore.
  • Set to 0 for no hole.
  • Notes:
  • For internal gear mode, this control may be disabled.

Display/preview tools

  • Preview Outline: overlays a “nominal” reference outline (uses clearance = 0 and backlash = 0) to compare against your current settings.
  • Reset View: resets pan/zoom for the 2D preview.

Export buttons

  • Download gear Profile (DXF format): exports the 2D profile suitable for laser/waterjet/CNC sketch import.
  • Download gear Profile (STEP format): exports a 3D solid (uses Thickness, Helix Angle/Hand, and other geometry inputs).

Practical tips

  • Start with 20° pressure angle, backlash = 0, clearance = 0, helix = 0 until the base shape looks right.
  • Add backlash and clearance once you know your manufacturing process and fit requirements.
  • If you plan to mesh two gears, ensure module and pressure angle match (and for helical gears also consider helix angle/hand and center distance).
Access the Gear Generator App

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