ork2step — OpenRocket → STEP Converter

Convert .ork (OpenRocket) files into fully editable STEP solids for import into Autodesk Fusion 360, FreeCAD, SolidWorks, or any STEP-capable CAD tool.

Works on Windows, macOS, and Linux. The actual conversion (parsing the .ork file and building the CAD geometry) is plain Python and runs identically everywhere. The one Mac-only piece is the .command files / Desktop-icon install flow (step 3 under Option A below) — that's just a convenience launcher specific to macOS. On Windows or Linux, skip straight to step 4 under Option A (docker compose up --build, no OS-specific setup) or use Option B (manual Python + Node setup), which already has separate Windows/Linux instructions throughout.

Features

Capability	Detail
Nose cones	Ogive, conical, ellipsoid, parabolic, power-series, Haack, spherical — including shoulder geometry if the .ork specifies one
Body tubes	Outer diameter, length, wall thickness → hollow shell
Transitions	Fore/aft diameters, conical or shaped shoulder
Fin sets	Trapezoidal, elliptical, freeform (approximated as a bounding trapezoid); angular pattern; tab geometry
Motor mounts	Inner tube as hollow cylinder
Launch lugs	Hollow cylinder at attachment point
Centering rings	Thin annular disc between motor mount and body tube
Tube couplers	Internal sleeve joining two body tube sections
Bulkheads	Solid disc sealing off a body tube
Engine blocks	Ring seating the motor casing against the tube
Missing params	UI prompts for wall thickness when absent from .ork
Output	AP214-compliant STEP — opens natively in Fusion 360

Installation

Windows or Linux? Skip the "(macOS only)" step below — that's a convenience launcher for Mac and won't run on your OS. Go straight to Option A, step 4 (docker compose up --build, works everywhere) or Option B (manual setup — has separate instructions for each OS). Everything else on this page works the same across all three platforms.

There are two ways to run ork2step: Docker (easiest, works on any OS) or manual setup (Python + Node.js installed directly on your machine). Both are covered below — pick whichever suits you.

Option A — Docker (recommended)

Docker bundles every dependency into containers, so you don't need Python, Node.js, or any system libraries installed.

1. Install Docker Desktop

OS	Download
Windows	https://docs.docker.com/desktop/install/windows-install/
macOS	https://docs.docker.com/desktop/install/mac-install/
Linux	https://docs.docker.com/desktop/install/linux-install/

After installing, open Docker Desktop and wait for it to show "Engine running" in the bottom-left corner before continuing.

2. Download the project

Without Git — download the ZIP directly:

⬇ Download ork2step.zip

Once downloaded:

macOS: double-click the ZIP to extract, then open Terminal and cd into the folder
Windows: right-click → "Extract All", then open Command Prompt and cd into the folder
Linux: unzip ork2step.zip && cd ork2step

With Git:

git clone https://github.com/max-h-25/ork2step.git
cd ork2step

3. (macOS only) Set up the desktop icon

Windows and Linux users: this step doesn't apply to you — skip to step 4 below.

Open Terminal, paste this single line, and press Enter:

cd ~/Downloads/ork2step-main/ork2step && xattr -rd com.apple.quarantine . && chmod +x install.command start.command stop.command && ./install.command

If your folder is named something different (like ork2step 6), replace ork2step in the cd path above with the actual folder name.

This strips the macOS security block from all files and creates a clickable ork2step icon on your Desktop.

From then on, just double-click the Desktop icon to launch — it starts Docker automatically, waits for everything to be ready, and opens your browser to http://localhost:3000.

To stop the app, double-click stop.command in the project folder.

If macOS says it "could not verify" install.command is free of malware: That's normal Gatekeeper behavior for any script downloaded from the internet — not a sign anything's actually wrong. Right-clicking (or Ctrl-clicking) the file and choosing Open doesn't reliably bypass it. Instead, do it from Terminal: run the cd ... && ./install.command line above exactly as written. The xattr -rd com.apple.quarantine part strips the block before the script ever runs, so Gatekeeper won't stop it.

4. Start manually (any OS)

If you prefer the terminal, or you're on Windows/Linux:

docker compose up --build

The first run downloads base images and installs all dependencies — this takes 3–10 minutes. Subsequent starts are fast (under 10 seconds).

When you see:

frontend  | Local:   http://localhost:3000/
backend   | Application startup complete.

go to http://localhost:3000 in your browser.

To stop: press Ctrl+C, then docker compose down.

Apple Silicon (M1/M2/M3): the Dockerfiles are already configured for ARM64 — no extra steps needed.

Option B — Manual setup (Python + Node.js)

Use this if you prefer not to use Docker, or want to modify the code and see changes instantly.

Prerequisites

You need three things installed before starting. Check whether you already have them:

python --version    # needs 3.10 or higher
node --version      # needs 18 or higher
npm --version       # comes with Node — any recent version is fine

If any of those commands fail or return an old version, install/update:

Tool	Download
Python 3.10+	https://www.python.org/downloads/
Node.js 18+	https://nodejs.org/ (choose the LTS version)

Windows users: when installing Python, tick "Add Python to PATH" on the first screen of the installer, or commands below won't work.

1. Download the project

Without Git — download the ZIP directly:

⬇ Download ork2step.zip

Extract it, then open a terminal inside the ork2step folder.

With Git:

git clone https://github.com/max-h-25/ork2step.git
cd ork2step

2. Set up the Python backend

Open a terminal and run these commands one at a time:

cd backend

Create a virtual environment (keeps dependencies isolated from the rest of your system):

# macOS / Linux
python3 -m venv .venv
source .venv/bin/activate

# Windows (Command Prompt)
python -m venv .venv
.venv\Scripts\activate.bat

# Windows (PowerShell)
python -m venv .venv
.venv\Scripts\Activate.ps1

Your terminal prompt should now start with (.venv) — this means the virtual environment is active.

Install the Python dependencies:

pip install -r requirements.txt

This step installs CadQuery, which includes a pre-built geometry kernel (~200 MB). It may take a few minutes. If it fails, see the CadQuery troubleshooting section below.

Start the backend server:

uvicorn main:app --reload --port 8000

You should see:

INFO:     Uvicorn running on http://0.0.0.0:8000 (Press CTRL+C to quit)
INFO:     Application startup complete.

Leave this terminal open. The backend runs here while you use the app.

3. Set up the frontend

Open a second terminal (keep the first one running the backend).

cd ork2step/frontend   # or just `cd ../frontend` if you're still in backend/
npm install
npm run dev

You should see:

  VITE v5.x.x  ready in xxx ms

  ➜  Local:   http://localhost:3000/

4. Open the app

Go to http://localhost:3000 in your browser.

5. Stop the app

Press Ctrl+C in the frontend terminal to stop the frontend.
Press Ctrl+C in the backend terminal to stop the backend.

CadQuery installation issues

CadQuery wraps the OpenCASCADE geometry kernel, which has platform-specific requirements. Here's what to do if pip install -r requirements.txt fails:

On Apple Silicon (M1/M2/M3 Mac)

pip may not have a pre-built binary for ARM. Use conda instead:

# Install Miniconda if you don't have it:
# https://docs.conda.io/en/latest/miniconda.html

conda create -n ork2step python=3.11
conda activate ork2step
conda install -c cadquery -c conda-forge cadquery
pip install fastapi uvicorn python-multipart lxml pydantic

Then start the backend with the conda environment active:

uvicorn main:app --reload --port 8000

On Linux (missing system libraries)

sudo apt update
sudo apt install libgl1 libglu1-mesa libxrender1 libgomp1
pip install -r requirements.txt

On any platform — if pip install times out or errors

Try installing CadQuery separately first, then the rest:

pip install cadquery
pip install fastapi uvicorn python-multipart lxml pydantic

Verify everything is working

Once both backend and frontend are running, open your browser to http://localhost:3000 and upload the included test file:

examples/alpha_iii_example.ork

You should see the rocket parsed (Estes Alpha III, 4 components), then be able to click Generate STEP File and download a working .step file. If that works, your installation is complete.

Troubleshooting

Same error keeps happening no matter what you change

If you've edited a backend file, or restarted the app, and it still behaves like the old version — same bug, same error, no change at all — there's almost always an old backend process still running in the background, quietly answering requests instead of the one you just started. Python doesn't reload a file just because it changed on disk; the old process has to actually be killed.

This is especially likely if you ever closed a Terminal window/tab instead of properly using stop.command — closing the window doesn't reliably stop the backend process running underneath it, so it keeps running and keeps holding onto port 8000. (Windows/Linux users running the manual setup: this is equally likely if you closed a Command Prompt/PowerShell/terminal window instead of pressing Ctrl+C.)

Fix — do this whenever things seem "stuck":

macOS / Linux:

lsof -i :8000

This lists whatever's currently using port 8000, including its PID (process ID). Then:

kill -9 <PID>

Windows (Command Prompt or PowerShell):

netstat -ano | findstr :8000

The last column of the matching line is the PID. Then:

taskkill /PID <PID> /F

(swap in the actual number from the previous command, on either OS). Now restart the app fresh — Desktop icon (macOS), or ./start.command/docker compose up --build/uvicorn ... — and try again. It's safe to run these check commands any time; if nothing's running on that port, they just come back empty.

When to reach for this:

You edited main.py, ork_parser.py, or cad_builder.py directly
You're not sure whether an earlier run of the app is still around
A previous session's terminal got closed without stopping the backend properly
Generating a STEP file gives an error that doesn't match what the code currently does

macOS says a `.command` file "could not verify" it's malware-free

Covered above in step 3 of the Docker install — right-clicking and choosing Open isn't reliable for this; run it from Terminal instead so the xattr -rd com.apple.quarantine step can strip the block first.

A part is missing from the STEP output with no error shown

Check the parse summary shown after upload — any component type ork2step doesn't support yet (bulkheads and engine blocks are supported now; things like shock cords, parachutes, and multi-stage boosters/pods currently aren't) is listed under "Not yet supported — excluded from the STEP output" instead of just silently vanishing. If something's missing and isn't listed there, that's worth reporting as a bug rather than an expected gap.

Project Structure

ork2step/
├── backend/
│   ├── main.py          # FastAPI app — upload & generate endpoints
│   ├── ork_parser.py    # .ork XML parser → intermediate geometry model
│   ├── cad_builder.py   # CadQuery solid builder + STEP exporter
│   ├── requirements.txt
│   └── Dockerfile
├── frontend/
│   ├── src/
│   │   ├── App.jsx      # Full React UI
│   │   └── main.jsx
│   ├── index.html
│   ├── vite.config.js
│   ├── package.json
│   └── Dockerfile
├── examples/
│   └── alpha_iii_example.ork   # Minimal test file (raw XML)
├── ork2step.app/                # macOS-only — app bundle for the Desktop icon
├── install.command              # macOS-only — run once, creates Desktop icon
├── start.command                # macOS-only — start the app manually
├── stop.command                 # macOS-only — stop the app cleanly
├── docker-compose.yml
└── README.md

On Windows/Linux, ignore the four macOS-only entries above — you'll use docker compose up --build or the manual Python/Node setup instead, both covered earlier in this README.

Pipeline Overview

User uploads .ork
        │
        ▼
[ Upload Handler ]          POST /upload
        │  validates ZIP/XML structure
        ▼
[ OrkParser ]               ork_parser.py
        │  extracts: NoseCone, BodyTube, Transition, FinSet,
        │            MotorMount, LaunchLug, CenteringRing,
        │            TubeCoupler, Bulkhead, EngineBlock
        │  detects missing CAD params (wall thickness)
        ▼
[ Intermediate Model ]      Python dataclasses
        │  all dims in metres, component hierarchy preserved
        │  MissingParam list sent to UI
        ▼
  User fills missing params (if any)   POST /generate
        │
        ▼
[ CadBuilder ]              cad_builder.py
        │  NoseCone   → swept profile → revolve (solid of revolution)
        │  BodyTube   → annular extrusion
        │  Transition → revolved trapezoid
        │  FinSet     → extruded 2-D profile × N (angular pattern)
        │  MotorMount → annular extrusion
        │
        ▼
[ cq.Assembly ]             CadQuery assembly with named bodies
        │
        ▼
[ STEP exporter ]           assembly.save(..., exportType="STEP")
        │
        ▼
User downloads  rocket_name.step

API Reference

`POST /upload`

Body: multipart/form-data, field file = .ork file

Response (JSON):

{
  "session_id": "uuid",
  "rocket_name": "Estes Alpha III",
  "summary": "Rocket: Estes Alpha III\n  Stage 1:\n    NoseCone ...",
  "component_count": 5,
  "missing_params": [
    {
      "component_name": "Body Tube",
      "param_name": "thickness",
      "description": "Wall thickness",
      "unit": "mm",
      "default": 2.0
    }
  ]
}

`POST /generate`

Body (JSON):

{
  "session_id": "uuid",
  "param_overrides": {
    "Body Tube::thickness": 1.6,
    "Nose Cone::thickness": 3.2
  }
}

Response: Binary STEP file (application/octet-stream).

`GET /health`

Returns {"status": "ok"}.

Nose Cone Geometry

Each nose shape is a true solid of revolution — not a mesh. The profile is sampled at 80 points and passed to CadQuery's spline → revolve pipeline.

Shape	Formula `r(t)`, `t ∈ [0,1]`
Conical	`R·t`
Ogive	Tangent-ogive: `√(ρ²–(L–x)²) – (ρ–R)`, `ρ=(R²+L²)/2R`
Ellipsoid	`R·√(1–(1–t)²)`
Parabolic	`R·(2t – k·t²)/(2–k)`
Power-series	`R·tⁿ`
Haack (Von Kármán)	`R·√((θ–sin2θ/2+C·sin³θ)/π)`

Fusion 360 Import

Open Fusion 360.
File → Open → Upload to Current Project → select the .step file.
Each rocket component arrives as a separate solid body in the Bodies folder.
Use Modify → Shell to adjust wall thicknesses interactively.
Use Assemble → Joint or As-Built Joint to constrain parts.

All geometry is parametric (B-rep solids), so you can edit sketches, extrusions, and revolves directly. No mesh conversion required.

Known Limitations

Issue	Workaround
Freeform fins (spline outline)	Approximated as a bounding trapezoid (root/tip chord, span, sweep taken from the outline's extremes) — not an exact match to the curved outline. Edit further in Fusion 360 if needed.
Shock cords, parachutes	Not modelled — these don't produce CAD geometry; listed under "not yet supported" in the parse summary instead of silently vanishing
Multi-stage boosters and pods	Not yet supported — the parser currently only reads top-level stages, not nested parallel stages/pods. This is a bigger architectural change, not just a new shape.
Launch lug radial position	Placed at origin; move in Fusion 360 assembly
Very old .ork (pre-1.5)	May use a different XML schema — open a GitHub issue
Component names	Different OpenRocket versions serialize the name field as either `<name>` or the abbreviated `<n>` — the parser checks both, but if you hit a file where a name still doesn't come through right, that's worth reporting

Extending

Add a new component type: implement _parse_<tag> in OrkParser and _build_<type> in CadBuilder. The dispatch tables in both classes are the only places that need updating.

Switch to FreeCAD backend: replace cad_builder.py with a FreeCAD Part API implementation — the Rocket dataclass model is CAD-tool-agnostic.

License

MIT — use freely, attribution appreciated.

Navigation Menu

Repository files navigation

ork2step — OpenRocket → STEP Converter

Features

Installation

Option A — Docker (recommended)

1. Install Docker Desktop

2. Download the project

3. (macOS only) Set up the desktop icon

4. Start manually (any OS)

Option B — Manual setup (Python + Node.js)

Prerequisites

1. Download the project

2. Set up the Python backend

3. Set up the frontend

4. Open the app

5. Stop the app

CadQuery installation issues

Verify everything is working

Troubleshooting

Same error keeps happening no matter what you change

macOS says a `.command` file "could not verify" it's malware-free

A part is missing from the STEP output with no error shown

Project Structure

Pipeline Overview

API Reference

`POST /upload`

`POST /generate`

`GET /health`

Nose Cone Geometry

Fusion 360 Import

Known Limitations

Extending

License

About

Releases

Packages

Contributors

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Name		Name	Last commit message	Last commit date
ork2step		ork2step
README.md		README.md

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Repository files navigation

ork2step — OpenRocket → STEP Converter

Features

Installation

Option A — Docker (recommended)

1. Install Docker Desktop

2. Download the project

3. (macOS only) Set up the desktop icon

4. Start manually (any OS)

Option B — Manual setup (Python + Node.js)

Prerequisites

1. Download the project

2. Set up the Python backend

3. Set up the frontend

4. Open the app

5. Stop the app

CadQuery installation issues

Verify everything is working

Troubleshooting

Same error keeps happening no matter what you change

macOS says a .command file "could not verify" it's malware-free

A part is missing from the STEP output with no error shown

Project Structure

Pipeline Overview

API Reference

POST /upload

POST /generate

GET /health

Nose Cone Geometry

Fusion 360 Import

Known Limitations

Extending

License

About

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Resources

Stars

Watchers

Forks

Releases

Packages

Contributors

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macOS says a `.command` file "could not verify" it's malware-free

`POST /upload`

`POST /generate`

`GET /health`