Richard Macfarlane was goofing around in his workshop one day about a year ago when his wife came up behind him.
"She said, 'What are you making?' and I said, 'it's a turbine,'" Macfarlane explained. "She said, 'Oh, what's it for?'"
It wasn't just some cutesy pinwheel he had made, but he didn't have plans for it.
Macfarlane had used his MakerBot Replicator 2 to 3D print a turbine made of PLA capable of spinning in excess of 60,000 rpms.
"I was staggered when I did the calculations (on its speed)," Macfarlane said.
But the question remains, "What's it for?"
Macfarlane, a retired mechanical design engineer from Perth, Australia, is hoping you can figure that one out. He's posted the turbine's STL file on Thingiverse along with some encouragement for anyone interested in finding a commercial use for it.
"You put this on the shelves of your local hardware store for $30, you would sell a million," he speculated.
If he had foreseen the amount of interest the turbine would draw back when he first created it, he figures he probably would have tried to market it himself. As it stands though, he's not looking for anything in return for the file.
"What would make me the happiest person on Earth would be to walk into some hardware store one day and see this on the shelf," he said.
The turbine is 35 mm in diameter. It's mounted on a 6 mm-diameter shaft and needs a couple of standard bearings. He estimates you could probably find a shaft on Amazon for about $10 and the bearings for about $3. Of course, if you want the turbine to spin at the speeds it is capable of for very long, you would probably need to upgrade the bearings.
"The shaft and bearings are absolutely crucial for this," he said.
It's a two stage turbine, which means it has two stationary stators that twist the air going in and two rotors that actually spin.
Macfarlane has mounted the turbine on a Dremel with a sanding disk on the end when working with carbon fiber in the past. It perfectly sucked up all the dust created from sanding process.
He and his wife recently took a trip to the Chinese city of Chengdu. They were overwhelmed by the amount of pollution in the air from workmen cutting concrete.
"A big version of this attached to some very serious machinery could actually be a very good way to reduced the amount of concrete dust going into the atmosphere," Macfarlane said.
He got the idea for the turbine while snooping around Thingiverse and found a design for a car that had an opening on top for a balloon. The opening directed the balloon's air backward, thereby propelling the car forward.
Macfarlane figured he could really make the thing go by adding a turbine. He made the turbine, but never got around to putting it in the car.
"To do that, you would have to add gears for a transmission," Macfarlane said.
And that didn't seem as much fun.
"It started out as a toy, but the possible commercial applications are enormous," Macfarlane said.