How to Make a Newton's Gravity Puzzle
Intro: How to Make a Newton's Gravity Puzzle
The Newton's Gravity Puzzle is a very simple puzzle. The objective is to remove the center piece while keeping the puzzle on a level surface. No tools can be used to remove it, only your body and the puzzle itself.
Here are the steps to make your own puzzle along with the solution at the end.
STEP 1: Tools and Materials
STEP 2: Inner Piece
This inner piece of the puzzle is made from an old cedar 4x4. However, any light would work here. I mounted it in the nova chuck and turned a cone on the end then turned it round to a diameter of 1 in.
Remove the piece from the lathe without parting it off.
STEP 3: Turn the Outer Shell
Turn the shell between centers then mount it in the nova chuck. Hollow out the center just larger than the inner piece. You want between 1/16 and 1/8 inch of clearance all the way around. This hole should be about 1 1/4 in. deep. Once the hole is at the correct depth, turn to the final diameter of 1 3/4 in and add a chamfer to the edge if you like.
Part it off at a length of about 1 1/2 in.
STEP 4: Cut the Inner Piece to Length
Once the shell is parted off, you want to cut the inner piece to the correct depth. The edge of the inner piece should be just below the shoulder of the shell. It should sit low enough in the shell that the inner piece can't be grasped with fingernails.
STEP 5: Sand and Paint
Sand and apply any color paint you like. I went with the traditional red of the original Newton's Gravity Puzzle.
STEP 6: How Does It Work?
Atmospheric pressure is present around every object on earth. The Newton's Gravity Puzzle is solvable through creating a difference in pressure above and below the inner piece. To overcome the acceleration of gravity, a gentle blow directly on the puzzle will decrease the pressure above the cylinder sucking it out and solving the puzzle.
21 Comments
Bill WW 5 years ago
From one mechanical engineer to another: if you have had your fluid dynamics courses, you know Newton had little to do with this. The puzzle is best explained by Bernoulli's equations, and demonstrated by an airplane wing - the moving air over the curved top of the inner part creates a lower pressure and lifts it out of the shell.
tomatoskins 5 years ago
kayakdiver 5 years ago
An enhancement might be to (perhaps secretly) hollow the plug to lighten it. And, I wonder if a less pointed top would create a better air foil providing more adhesion (less stall or "spoilage") of the air to the surface.
It would be cool if the viewer didn't see you blowing on it when you demonstrate it.
Bill WW 5 years ago
MathiasE5 5 years ago
kayakdiver 5 years ago
tomatoskins 5 years ago
JohnSmith-Workshop 5 years ago
JT Woodworks 5 years ago
YanO6 5 years ago
tomatoskins 5 years ago
Arbormakes 5 years ago
AndrewH345 5 years ago
DawsonC10 5 years ago
macwiley 5 years ago
You've inspired me to replicate it for 3d printing. See it at https://www.thingiverse.com/thing:3167661
tomatoskins 5 years ago
macwiley 5 years ago
Alex in NZ 5 years ago
Build-Bot 5 years ago
Nice job, tomatoskins!
ynze 5 years ago