Parametric Roller Coaster Track Generator

A powerful Python and OpenSCAD toolchain for generating 3D-printable roller coaster tracks. This tool accepts 3D coordinates (via CSV or algorithms), turns them into smooth track geometry, and intelligently slices the model into printable segments with interlocking connectors.

Features

• Parametric Geometry: Generates realistic track profiles with rails, crossties, and a spine.
• Intelligent Slicing: Automatically partitions long tracks into segments that fit your 3D printer's build volume.
• Interlocking Connectors: Automatically generates male/female connectors (pegs and sockets) with configurable tolerance for easy assembly.
• Banking & Orientation: Calculates correct banking and frame orientation vectors (Forward, Up, Right) for every point on the track.
• CSV Support: Import your own track designs from simple CSV files.
• Automated Rendering: Renders all segments to STL files in one command.

Prerequisites

1. OpenSCAD: This tool relies on OpenSCAD for 3D generation.
   • macOS: Install via brew install --cask openscad or download from openscad.org.
   • Windows/Linux: Install from openscad.org.
2. Python 3.11+
3. uv (Recommended): A fast Python package and project manager.

Installation

1. Clone the repository:

   git clone https://github.com/conceptcodes/rail-forge.git
   cd rail-forge

2. Initialize the environment:

   uv sync

Usage

The primary interface is generate.py.

1. Generate a Demo Track

If no input file is provided, the tool generates a demo helix/loop track.

uv run generate.py --render

2. Generate from CSV

You can provide a CSV file containing x, y, z coordinates.

# or use one of the example tracks
uv run generate.py tracks/left_turn.csv --scale 100 --render

3. Slicing for Your Printer

Use the --max-length argument to specify your printer's bed size (in mm). The tool will split the track into segments that fit.

# For a printer with a 256mm build plate
uv run generate.py tracks/helix.csv --scale 100 --max-length 250 --output-dir my_coaster --render

This will produce files named track_segment_01_of_XX.stl inside the my_coaster/ directory.

Command Line Arguments

Argument	Description	Default
file	Input CSV file (optional).	Demo Helix
--scale	Scale factor for input points.	1.0
--max-length	Maximum length of a track segment in mm.	250.0
--render	Automatically render STL files using OpenSCAD.	False
--openscad	Path to OpenSCAD executable.	openscad
--output-dir	Directory to save generated STL files.	.

CSV Format

Your CSV files should contain 3 columns (X, Y, Z). Headers are optional (the parser skips lines that aren't numeric).

0.0, 0.0, 0.0
10.0, 5.0, 2.0
20.0, 10.0, 5.0
...

See the tracks/ directory for examples:

• straight.csv: Basic straight track
• helix.csv: Unit-circle spiral (requires scaling)
• airtime_hill.csv: Parabolic hill
• left_turn.csv / right_turn.csv: 90-degree turns

Project Structure

This project is structured as a modular Python package:

generate.py           # CLI entry point
track.scad            # OpenSCAD geometry definition
spline_data.scad      # (generated) data file passed to OpenSCAD
tracks/               # Example CSV tracks
src/
│   └── roller_coaster/
│       ├── geometry.py   # Vector math & path generation algorithms
│       ├── track.py      # Slicing & partitioning logic
│       ├── io.py         # File I/O (CSV reading, SCAD writing)
│       └── render.py     # OpenSCAD process orchestration
└── pyproject.toml        # Project configuration

Customizing the Track Design

You can modify track.scad to change the aesthetic of the coaster:

• track_gauge: Width between rails.
• rail_diameter: Thickness of the rails.
• crosstie_spacing: Distance between ties.
• tolerance: Fit tolerance for connectors (default 0.2mm).