Hole calc is a simple web application that allows you to calculate the diameter of a bore from the size of three cylindrical pin gages that fit into it, using Descartes' Theorem. This functionality is useful for machinists and anyone else who needs a semi-precision method of measuring bore diameters without dedicated tools. See the guide for more info on how to use hole calc.

The hole calc application is built with the Flask web application microframework. Flask-WTForms was used to build the calculator input forms. The source code for the flask app is contained in main.py, while Flask templates reside in the templates subdirectory.

The holecalc module contains the backend code that runs the geometry calculations for the application's main functionality. This module also contains a couple placeholder functions that need to be completed for future planned features (see TODO section below).

Hole calc is styled using Pure.css. The display font used for the menu and headings is Space Grotesk by Florian Karsten. The color scheme may be viewed here.

Hole calc is developed and tested using Python 3.8. A pipfile is included for dependency management with Pipenv.

The preferred way to build and deploy this application is via Docker, using the included Dockerfile. The base image used is tiangolo/meinheld-gunicorn-flask:python3.8 (docs).

Automated tests for the pytest framework are found in the tests subdirectory. Tests and linting with flake8 are run via GitHub action on every push to the master branch of this repository.

The following environment variables should be set during deployment:

• FLASK_ENV: Use 'development', 'testing', or 'production'. Defaults to 'development' if not set.
• SECRET_KEY: A secret key that will be used for securely signing the session cookie. Used for CSRF form validation. Not very important to guard against CSRF attacks currently, but this future proofs the app for potential added features.

• Hole calc is currently feature complete so there are no major pending TODOs. However, small improvements and optimizations are always possible. If you have a suggestion, check out the "Contributing" section below.

Bug reports, feature suggestions and code contributions are welcome. You may open an issue or pull request through GitHub or by contacting me directly through the contact information listed on my GitHub profile.

Hole calc is licensed according to the terms of the MIT license. See LICENSE.md for details.