The top surface of the machine is cut from 1/2″ thick plywood, using a CNC router to make 3/8″ deep channels where the balls can roll. After routing, we added all of the labels by laser engraving. The flip-flops and switches are laser cut from thinner plywood, and rotate on simple plain bearings consisting of 1/16″ diameter stainless steel pins and slightly larger holes drilled through the wood. At the upper right, you can see the ball-release mechanism, which releases a ball when the actuated by the pushrod. As with our giant model, the design is a functional but not exact replica of the original. All of the flip-flops, registers, and switches are approximately in the original locations, but the “wiring” (really, rolling ball paths) has been created from scratch. One of the non-obvious things when you first look at the Digi-Comp II is that there are actually two levels to the machine. The six “black holes” that you can see above drop the ball down to the lower level, as a shortcut to the bottom or (for certain functions) to flip switches on the top side.
On the bottom half of the machine you can see the ball return as the stripy ramp in the center. The stripes on the ramp arise from cutting plywood at an angle (see here for another example). Below that is the Start Lever. When a ball presses down the start lever, it pushes the pushrod that releases the next ball from the top.
We’ll be demonstrating our prototype Digi-Comp II all weekend at Maker Faire. If you’re in the area, please drop come see the Maker Faire, say hi, and try it out!
- Additional resources:
- If you’d like more information about the Digi-Comp II in general, please take a look at our prior articles (again, with photos and with video).
- The official site for our project is digicompii.com
- If you are interested in the forthcoming kit version, please sign up for the Evil Mad Science Mailing List.