In German, I knew it as the "Hui spiel" (Hui game), and I was able to find it online under that name as well. In English, it's usually called a "hooey stick", but also "magic propeller stick", "geehaw stick" or "geehaw whimmy diddle".
The game is a rather simple sort of "magic trick". You rub the dowel on the stick with the propeller, and the propeller turns. And when you say "Hui" (pronounced like hooee, but with an emphasis on the e), the propeller reverses direction.
Then you let other people try it, but when they rub the dowel across the stick nothing happens!
The hui consists of just a stick with notches carved into it and a propeller on the end, plus a dowel to rub across those notches. The trick is in how you rub the dowel along the stick, and to do it in such a way that people can't tell what you are doing.
I'll explain the trick at the end of the article.
The easiest way to cut out the notches is to place the stick on a V-block and cut them out with a bandsaw. If you don't have a bandsaw, you can carve them out with a knife or file them out. But I broke my wrist recently, so I'll stick to using power tools for the time being.
Next we need to make the propeller...
The propeller is made from a piece of wood about 2-3 mm thick. I drilled a 1/4" (6 mm) hole in it. Next, I used a compass to mark the outline of the propeller, and then cut that out with a bandsaw. This way, I can be sure that the hole is in the middle.
The propeller fits very loosely over a screw or nail. The hole is sized to give maximum play without the propeller falling off the screw. It's a combination of the looseness of the propeller over the screw (or nail) and the vibrations that actually makes it spin.
It helps to roughen the shank of the screw a little bit to help drive the propeller. I'm pressing a file firmly down on the shank and rolling it back and forth to knurl it.
The knurled shank
Next, drilling a hole in the end of the stick. The hole is sized just a tiny bit larger than the major diameter of the threads. Otherwise, there's risk of splitting the stick. If the screw ends up too loose, you can always fill the hole with glue before you put the screw in.
Your fingers end up touching the edges of the notches when operating the hui, so it's best to smooth those out a bit. I'm using my strip sander, touching the hui against the part where the belt doesn't have any backing. Hand sanding would work too, but I bought this strip sander absurdly cheap just recently, so it's fun to find new uses for it.
Also sand the corners at the ends of the stick. That will make it more comfortable to hold at the back and allow the propeller turn more easily at the front.
To make the propeller turn clockwise, you need to press a finger onto the other side of the stick. With the index finger reaching over the stick, press the side of it against the stick. Ideally, you'll be pressing the side of the finger nail against the stick.
The key to not giving away the trick is to always have both fingers in place and to press the stick against one finger or the other. If you keep your fingers close enough all the time, it's really hard to tell that you are pressing with one finger or the other. That makes the whole thing look like magic!
When I took video of this hui, I was able to get the propeller to spin fast enough that it appeared to stand still. With my camera shooting 30 frames per second, that means the propeller was turning at 15 turns per second, or about 900 RPM.
Stevin Ramsey has recently done a video on building one of these, although he wasn't able to get his going nearly as fast. He should have made a bigger hole in the propeller!
I recently make two of these for my nephews for Easter, but, as it turned out, the adults were much more fascinated by it than the kids. In retrospect, I guess it only makes sense. To a four year old, the whole world is full of magic, so a little propeller that spins when you rub two sticks together doesn't seem very special. But to adults who profess to understand the world around them, that little bit of "magic" is fascinating.
If you are wondering about the outfits these two in this picture are wearing, see here.