Printed Gears... What?!

RepRap is undertaking a fairly mindblowing project: They're trying to make a self-copying, open-source 3D printer. (And you thought Avatar in 3D was impressive!) Think about that for a moment. They're trying to construct a 3D printer than can reprint itself. Endless self-iterations. Amazing.

RepRap's blog is documenting their progress, and they've just gotten their printer to print gears that it can use:

I have finally managed to print tiny little ball-chain gears that work with 3.3mm and 3.5mm diameter ball-chain and still fit on the NEMA17's 5mm output shaft. The trick is to print the gears in two pieces.

As you can see in the photograph, I print two 4mm thick sections of gear and put them on the shaft with an M5 washer sandwiched in between. Make sure the teeth are lined up on both gears. This gives a channel to guide the ball-chain down the centre of the gear, and grips the sides of the balls adequately. As the gears age, it will also stop the balls grinding their way too far through the PLA, though I must admit that my experience with ball-chain Z axis gears suggests this will not be a major issue.

This is a really cool project that we'll be sure to follow along with. Good luck, guys!