Introduction: Nail in Solid Brick Puzzle
Common objects in uncommon configurations will always spike interest. In this instructable you will learn how to make and remove a nail in a solid brick ring.
This puzzle is simple and inexpensive to build. All materials can be found at your local home center for less than a dollar and can be built in a couple hours.
Step 1: Tools and Materials
Step 2: Drill Center Hole
Drill a 7/8 in. hole in a piece of scrap wood and clamp it over one half of the brick. Fill the hole will water to lubricate the drill bit. Drill the hole until the bit bottoms out. Remove the plug and drill through the remainder of the brick.
Step 3: Cut and Rough Brick
Using an angle grinder with a diamond blade, cut the brick in half and remove the corners.
Step 4: Turn Brick
Mount the ring on a roughed out mandrel on the lathe. Using the lathe tool rest, support the angle grinder using the blade guard. Run the lathe slowly until round with a diameter of about 2.9 in.
Step 5: Part Off
Using the angle grinder on its side, cut the ring 3/4 in. thick.
Step 6: Sand
Sand the exterior of the ring on the disc sander. Add a chamfer to the outside of the ring using a 45 degree piece of scrap wood.
Step 7: Drill Nail Hole
Mark and drill a hole through one side of the ring through the center with a 7/32 in. masonry bit.
Step 8: Cut Nail
Cut the nail at 1 1/4 in. from the top of the head. Using the disc sander, shorten the length of the shaft until it just fits into 7/32 in. hole through the center of the ring (should be short enough around 1 in. but do not go shorter than necessary). When in place, you should not see the cut end of the nail in the 7/32 in. hole.
Step 9: Tap
Drill and tap an 8-32 UNC 5/8 in. into the shaft of the head. Use the tail stock as shown in the next step to ensure that the threads are concentric with the shaft.
Step 10: Thread Nail
Cut a thread relief 3/8 in. from the end of the shaft with a hack saw. Using a file, reduce the size of the shaft to ~.164 in. Use the tail stock to keep the threads straight.
Test the threads between the shaft of the nail and head.
Blend the seam between the two pieces by making the edge of each of the two pieces as square as possible.
Step 11: Shine
Polish the nail to your liking. I liked the brushed finish look, so all I used is 400 grit sandpaper to finish the nail while the lathe is on.
Step 12: Solve
To assemble the puzzle, insert the head of the nail through the center of the ring. Screw the shaft of the nail into the threads of the head of the nail.
This puzzle works because of the exact inner and outer diameters of the ring. No matter if the nail is slid inside the ring being stopped by the other side or outside being stopped by the head of the nail, the seam in the nail will always be hidden.
You can turn this into more of an 'impossible object' by securing the threads with some Loctite. No one will be able to figure out how it was assembled unless it is broken. .
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