I’m delighted at how well the lunar clock is going! While waiting for stepper motors to arrive, I’ve been using Inkscape to create the laser-cutting pattern for the wheel that will contain images of the various phases of the moon. After a few hours of stumbling around (I’d never used Inkscape), I was drawing circles, arcs, and lines with abandon.

The idea of the clock is that this wheel will be behind a picture of a sky, that has a moon-sized hole near the top. The wheel will rotate to show the lunar image that most closely resembles the current phase of the moon.

I had hoped to put12 lunar images in the wheel, but that made the wheel too large and the lunar images too small. 8 images makes everything just the right size.

I’ve never done laser cutting before, so I signed up for Ponoko, a popular laser cutting service in New Zealand and the United States. It’s been a breeze ordering my first Lunar Wheel, to be cut from a 15-inch-square, 1/8″ thick piece of MDF. I simply downloaded the template into Inkscape, followed the design rules, and voila!

One cautionary blog called Scale Fail recommended that you prototype for laser cutting in 3 stages:

1. Test the size. Print your design full-scale on your paper printer and see if it looks right. This is the stage pictured above: I’m checking that the screw hub holes are properly placed and are the right size, and I’m checking that the slot is the right size to make the photo-interrupter work well.
2. Then laser cut in cheap cardboard. You’re likely going to make some mistakes (even small ones), so it’s good to get through them using cheap materials.
3. Now print the real thing.

Since Ponoko offered a $20 discount on my first order, I decided to skip cardboard and go straight to MDF. It will be a good test piece regardless of whether it works out. Without the discount, the pattern above, in the MDF I described, shipped to me with a little speed, would have cost about $30. Not bad considering that to make another I just push a button rather than spending a weekend with the scrollsaw.

Now I can’t wait for my Lunar Wheel to arrive!