johnwebbcole / bahtanov

A jscad bahtanov generator for small scopes.

bahtinov

A Bahtinov mask for small scopes.

Create a custom Bahtinov mask by clicking in here, and opening OpenJSCAD

What is a Bahtinov mask?

A Bahtinov mask is a focusing aid for astrophotography, invented by Pavel Bahtinov in 2005. Before this, a Hartman mask, or variations of, was often used to focus a telescope

You can get a mask for your telescope from different vendors now. This is quick and easy, but if you have multiple scopes, or have scopes that are smaller, it can be difficult to find them.

Online Generator

AstroJargon has a nice Bahtinov mask generator. It will create a SVG file that you can print on card stock and cut it out.


Or you can send the SVG off to be laser cut. These are nice for large scopes.


Small scopes

One issue for small scopes is that the slits in the mask are small, and using a hobby knife to cut them out is difficult. Also, the narrow paper slits do not stand up well to dew.

Laser cutting has similar issues with small slits, the plastic around the slits melts and warps. Using plywood or MDF works better.

Since I have a 3D printer, I decided to print some for my guide scopes.


Now you can print them out too. Use the link here to open the project in OpenJSCAD.

Development

The jscad project bahtinov uses gulp to create a dist/bahtinov.jscad file and watches your source for changes. You can drag the dist/bahtinov.jscad directory into the drop area on openjscad.org. Make sure you check Auto Reload and any time you save, gulp will recreate the dist/bahtinov.jscad file and your model should refresh.

jscad-utils

The example project uses jscad-utils. This is a set of utilities that make object creation and alignment easier. To remove it, npm uninstall --save jscad-utils.

Other libraries

You can search NPM for other jscad libraries. Installing them with NPM then running gulp should create a dist/bahtinov55.jscad will all dependencies injected into the file.

For example, to load a RaspberryPi jscad library and show a Raspberry Pi Model B, install jscad-raspberrypi using npm install --save jscad-raspberrypi. Then return a combined BPlus group from the main() function.

main()   
  util.init(CSG);

  return RaspberryPi.BPlus().combine();
}

// include:js
// endinject

Publishing

If you publish the dist/bahtinov.jscad file, you can open it directly in

<openjscad.org> by using the following URL: http://openjscad.org/# + the url to your file.</openjscad.org>

Gist

You can save your file to a github gist and append the url to the raw gist.

For example: http://openjscad.org/#https://gist.githubusercontent.com/johnwebbcole/43f2ef58532a204c694e5ada16888ecd/raw/d0972463f70222e6d4c6c6196a1c759bb3e2362a/snap.jscad

Pastebin

Or use pastebin like:

http://openjscad.org/#http://pastebin.com/raw/9CjvuhSi

License

ISC © John Cole