Is it really possible to build a rotary encoder out of a flattened tin can and a couple of photodetectors? Sure it’s possible, but what kind of resolution are you going to get from such a contraption?

Here’s a great CNC hack that adds a ton of functionality, a DIY rotary 4th axis! [Jim] had started this project over a year ago when he originally ordered the gearhead off eBay, but like many good ...