Canadian Woodworking

Lie detector puzzle

Author: Rea Gibson
Published: February March 2002

This is a fun project that is easy to make and will create lots of laughs at a party. It has been around for many years and has been called many names.


The fan spins as you rub the notches with another piece of wood, while at the same time, holding a finger on one side of the shaft. When you hold your finger on the other side of the shaft the fan will spin in the opposite direction. Because you can change the pressure from one finger to the other, without anyone noticing, the fan will change direction under your control (or whenever a lie is told!).


Hold the shaft in one hand and rub the notches, as shown, with one finger on each side of the shaft. When you detect a lie, simply change the pressure from one finger to the other and the direction in which the fan turns will reverse. It takes a bit of practice, but is easily mastered and quite effective.

Don’t tell how it works right away, and watch how everyone tries to get it to work for them. Besides, if they don’t know how to use it, they’ll never catch you in a lie!


From last issue’s Three-Way Cross Puzzle

1. Set block #3 into block #2 with the thin end up.

2. Drop the top of the #3 block back 90° as shown.

3. Push block #1 into block #2 as shown as step 1.

4. Lift blocks #1 and #3 up as far as they can go into block #2.

5. Slide block #3 back into place and the puzzle is complete.

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