Magnetic Slider Puzzles

According to Wikipedia, sliding puzzles have been with us for a very long time. The classic 15 Puzzle shown above was "invented" by Noyes Palmer Chapman around 1874. Over the years there have been many variations on the original, with colored blocks, jumbled pictures, variously sized grids, etc.. I have fond memories of playing with the 15 Puzzle and some of the variants growing up.

These puzzles all follow the same pattern, a shallow box base holding a grid of flattened square blocks, with a single block missing. Adjoining blocks can be slid into the empty space leaving behind a new empty space. In this way blocks can be moved around the board (one at a time) to "solve" the puzzle by arranging the pieces in a particular pattern. A clever tongue and groove mechanism held the movable pieces firmly to the base, yet allowed them to slide freely into the empty space.

A quick search shows that there are many Instructables already that show you how to make various kinds of sliding puzzles. Angus from Makers Muse has a great video on making "print in place" sliding puzzles. So why am I creating this Instructable? Well because all of the examples mentioned here use the classic tongue and groove mechanism to hold the pieces in place and I think that I have a better way, magnets.

I was inspired to make sliding puzzles with magnets by another of my projects the "Mostly 3D Printed Slider Switch". The switch used magnets to "snap" a sliding bar into one of five preset positions. It had a very satisfying "feel" that I though would translate well to moving pieces around a slider puzzle. I think I was right. For the slider puzzle, magnets not only serve to hold the pieces securely onto the base without the need for a mechanical tongue and groove mechanism, they also help to snap the blocks into place when sliding them into the empty square. It just feels right.

Let's get started with the classic 15 puzzle.

Supplies

In addition to the 3D printed parts you will need:

• 64 - MB-THISTAR 3 mm x 1.5 mm Disc Rare-Earth Neodymium Magnets (Amazon)

Step 1: Print the Parts

I printed the parts with the following settings:

Print Resolution: .2 mm

Perimeters: 2

Infill: 15%

Filament: AMZ3D PLA

Notes: No supports. Print the parts in their default orientation. For the numbered pieces I changed the filament at the 4.2 mm point from white to blue.

To make the 15 slider puzzle you will need the following:

• 1 - Base
• 1 - Base Gasket
• 1 - One Piece
• 1 - Two Piece
• 1 - Three Piece
• 1 - Four Piece
• 1 - Five Piece
• 1 - Six Piece
• 1 - Seven Piece
• 1 - Eight Piece
• 1 - Nine Piece
• 1 - Ten Piece
• 1 - Eleven Piece
• 1 - Twelve Piece
• 1 - Thirteen Piece
• 1 - Fourteen Piece
• 1 - Fifteen Piece

Step 2: Add Magnets to the Base

I inserted 16 of the 3 mm magnets into the Base holes. I used a small amount of glue to hold them in place securely.

Important: Make sure that the magnets as they sit all have the same polarity, and that they are seated into to the holes level or just a little below the lip of the hole.

Step 3: Add the Base Gasket

Cover the Base magnets with the Base Gasket. It should just snap tightly into place, but use a bit of glue to secure it if necessary.

Important: Be sure to install the gasket with the smooth first layer side facing up. This will ensure that number pieces slide smoothly along it's surface.

Step 4: Add Magnets to the Number Pieces

Install one of the 3 mm magnets into each of the 15 number tiles. Use a bit of glue if necessary to securely hold them.

Important: Make sure that the magnets as they sit all have the opposite polarity to those of the base magnets. That is to say that the magnet at the bottom of the tile should attract the magnets in the base. Also see that the magnets are seated into to the tile holes level or just a little below the lip of the hole.

Step 5: Drop the Number Pieces Into the Base

I you have gotten all of the magnet polarities correct, the number pieces should sit securely in the base. Moving the pieces around should be smooth and easy. If any of the pieces try to "hop out of the base" then you have the polarity wrong. Go back to Step 2 and check your work.

Important: Starting with the "solved" position shown above you can now scramble the pieces, using the slider mechanism only, then try to solve the puzzle. While it is tempting to just put the pieces in randomly to begin with, only half of the resulting random starting positions will be solvable. You are warned.

Step 6: Make a Word Puzzle (Optional)

If you are looking for a bit more of a challenge this word puzzle might be for you. Assuming that that your Base is complete, print the following pieces:

• 3 - A Piece
• 1 - B Piece
• 2 - E Piece
• 1 - H Piece
• 1 - L Piece
• 2 - O Piece
• 1 - P Piece
• 2 - R Piece
• 2 - T Piece

Add the magnets to the pieces as per Step 4 and drop them into the base.

Important: Place the pieces in the order shown in the picture above.

From this starting position the goal is to end up with eight words. The top three rows and leftmost three columns will have 4-letter words, and the last row and rightmost column 3-letter words. Good luck.

Step 7: Make a Path Puzzle (Optional)

Another challenging puzzle is this path one. Assuming that your Base is complete, print the following pieces:

• 1 - Start Piece
• 1 - Finish Piece
• 1 - Blank Piece
• 3 - Horizontal Piece
• 3 - LR Corner Piece
• 1 - LL Corner Piece
• 2 - UR Corner Piece
• 3 - UL Corner Piece

Add the magnets to the pieces as per Step 4 and drop them into the base.

Important: Place the pieces in the order shown in the picture above. Be careful to get the orientation of the pieces correct with the "dot" in the upper left corner.

From this starting position the goal is to end up with a single path starting at the S(tart) block and ending at the F(inish) piece using all the pieces with line segments. Have fun.

Step 8: Final Thoughts

Replacing the "tongue and groove" mechanism of the classic sliding puzzle with magnets greatly simplifies the design. Pieces still adhere to the base well and slide smoothly and easily. Operating the puzzle just "feels" great! I suppose that the magnet solution makes "cheating" a little easier, but it also allows you to readily swap tile sets with new puzzles onto a single base (as I have done with the Word and Path puzzles that I created).

All in all I am pretty happy with the result presented here.