CNC Router Cut CD Ninja Stars (Including GCode and CAD files)!

cd ninja star and "shuriken"Behold, the CNC cut CD ninja star!  At one point I believed I had invented the CD ninja star, but a quick search of Google proved me very wrong.  As far as I can tell though, this is the first one that is cut with a CNC router, so maybe that’s something.

The picture to the right is, unfortunately, a result of placement, not the actual star sticking in the dartboard after a throw.  Not that this wasn’t attempted.  The shuriken in the upper left was a result of one of the points breaking off.

Not the sturdiest weapon in the world.  After cutting off another point to make it symmetric, it’s flight is still impressive if incredibly random.  I tested it out in the house (not recommended) where it arced around a wall nearly poking my wife in the eye.

Cutting was done with an engraving bit from ZTW at a depth of cut of .010″ per pass.  I didn’t offset anything, but just drew it and cut as an engraving.  The CD was fixtured the same way as the last HDD clock that I did, but one difference was that the zero of the X and Y axes were on the edges (shown by the green and red lines in the CAMBam picture after the break), not the center.  This allowed me to line everything up based on an edge instead of estimating the center of it.

It seems that things cut much better if started from the side with a picture.  Things seemed to delaminate from the other side, but this could also be a result of using an industrially-written CD instead of writeable media.

It’s ironic to me how far we’ve come when something that was an incredible piece of technology 20 years ago is now so cheap that it has become a great material to make useless items like plastic ninja stars (drink coasters?) out of!  Be careful with these if you make one.  Especially the 3-pointed random trajectory “shuriken” I eventually ended up with.  It seems especially prone to random point attacks!

As promised, here are the links for the Gcode to do this if you’d like to try it yourself, as well as the DXF CAD file that I used.  If you can identify the CD that I made the yellow star out of, I will be extremely impressed (hint: it’s from a computer book).


  1. I actually used to cut up scratched CD’s with scissors, but they generally ended up looking more like a buzz saw blade than a ninja star. Anyhow, this post took me back.

    Keep up the good work on your blog. It’s definitely better than the Communist blogs I’m used to reading.

    • Comrade Salvador,

      I am happy for your kind comments and to hear that you too are a fan of improvised Oriental weapons.

      Glad to hear that you are no longer reading dirty Pinko websites, and have seen the light of Glorious Capitalism as I have. Perhaps we can meet for tea in the future.

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