SketchUp Plugin Involute Gear

Plugin Introduction

This is a powerful SketchUp involute gear generation plugin that supports parametric modeling of various gear types. This derivative work is based on Mark Jason Grundman’s SPGears_mjg.rb (Version 1.01) with significant modifications and enhancements, providing full-series gear design capabilities from micro drives to extra-large equipment.

Note: This blog post was translated from Chinese to English using AI. Please excuse any non-standard terminology.

The plugin’s interface language and code comments are in Chinese. You can use AI to translate them into English.

Plugin Interface Showcase

Below are the actual operation results of the plugin:

Circle Resolution: Sets the number of segments on the gear’s circumference. When your gear is too small, SketchUp doesn’t support circles with too many segments, so this is forcibly set.
Scale Factor: When the gear is too small, you can enlarge it using the scale factor to make it visible in SketchUp.
Video Demonstration

Core Features

1. Diverse Gear Types

External Gear: Standard involute cylindrical gear
Internal Gear: Internal ring gear design (recommended teeth ≥ 30)
Bevel Gear: Achieved through bevel angle parameter
Helical Gear: Achieved through helix angle parameter

2. Intelligent Parameter Validation System

The plugin has a built-in multi-layer parameter validation mechanism:

Layer 1: Automatic Application Type Recognition

Automatically determines the gear’s application type based on the input addendum circle radius:

Micro Drive (<10mm): Micro robots, precision instruments
Precision Instruments (10-50mm): Clocks, instruments, meters
Small Machinery (50-150mm): Small motors, home appliances
General Machinery (150-350mm): Machine tools, automotive transmissions
Heavy Machinery (350-1500mm): Construction equipment, mining machinery
Large Equipment (1500-5000mm): Wind power generation, marine propulsion
Extra-Large Equipment (>5000mm): Large mining machinery

Layer 2: Parameter Range Validation

Each application type has recommended parameter ranges:

Tooth Count Range: From 6 teeth (micro) to 300 teeth (extra-large)
Module Range: Standard series from 0.1mm to 100mm
Profile Shift Coefficient Range: Reasonable range recommended based on application type
Addendum/Dedendum Coefficient: Recommended combinations for different applications

Layer 3: Geometric Rationality Validation

Dedendum circle radius > 0
Addendum circle radius > Base circle radius
Tip thickness meets minimum material requirements
Undercut risk assessment

Layer 4: Intelligent Correction Suggestions

When parameters don’t match, automatically provides multiple correction options:

Adjust tooth count to match addendum circle radius
Adjust module to match addendum circle radius
Accept calculated value as recommended addendum circle radius
If parameters don’t match and you choose forced generation, it will still generate a gear matching the addendum circle radius

3. Material Database

Supports multiple gear materials with their minimum tip thickness requirements:

Hardened Steel (0.25): Heavy-duty, high-speed transmission
Tempered Steel (0.30): General machinery
Cast Iron (0.40): Low-cost, low-speed transmission
Bronze (0.35): Wear-resistant, suitable for worm gear drives
Plastic (0.50): Light-load, quiet operation, corrosion-resistant
Aluminum Alloy (0.45): Lightweight design

4. Advanced Geometric Features

Addendum/Dedendum Coefficient Combinations

Multiple standard combinations available (user input required):

Standard Combination (1.0/1.25): Balanced performance, general purpose
Short Tooth Combination (0.8/1.1): Increased strength, undercut prevention
Long Tooth Combination (1.2/1.35): Increased contact ratio, noise reduction
High-Strength Combination (0.75/1.15): Heavy-load applications

Intelligent Profile Shift Coefficient Handling

Automatically calculates minimum tooth count without undercut
Automatically adjusts reasonable profile shift coefficient range based on tooth count
Special restrictions for internal gear profile shift coefficient (≤0.5)
Automatic tip thickness calculation and validation

5. Additional Features

History recording support
Input parameter annotations
Source code includes comments and knowledge points for easy learning and modification

Included Files and Installation Methods

1. Plugin Source Code

Main Program: MySPGear.rb
Utility Tools: ToolModule.rb (required by the main program)

2. Installation Methods

Method 1: Using My “Plugin Tray”

Place the “main program” anywhere within the plugins folder, and place the “utility tools” in the plugins root directory. See my previous blog post for the “Plugin Tray” source code.

Method 2: Direct Installation (Without Plugin Tray)

If you don’t want to use my “Plugin Tray”, you need to place both the main program and utility tools in SketchUp’s plugins root directory, and modify the code as follows. It will then appear in your “Extensions” menu:

(1) Comment out all hot-reload related code:
  #require 'D:/MySketchUpPlugin/src/hot_reload.rb' 
  #HotReload.enable(__FILE__) if defined?(HotReload)

(2) Add at the beginning of the main program:
  require 'ToolModule.rb'

(3) Add at the end of the main program:
  #=============================================================================
  # Menu Registration
  #=============================================================================
  unless file_loaded?(__FILE__)
    # Get the Plugins menu (works correctly in both English and Chinese SketchUp)
    plugins_menu = UI.menu("Plugins")
    
    # Add separator (optional, for better menu appearance)
    plugins_menu.add_separator
    
    # Add menu item
    # When clicked, creates a MySPGear instance and calls the run method
    plugins_menu.add_item("My Involute Gear") {
      MySPGear.new.run
    }
    
    # Mark file as loaded to prevent duplicate menu entries
    file_loaded(__FILE__)
  end