Introduction: Grid-Blocked: Wooden Logic Puzzle

This Christmas, my siblings and I decided to set a price limit of $10 for our gifts for each other, since most of us are unemployed students. My plan was to build everyone a little something. This instructable covers the first of my gifts: a wooden version of the puzzle Rush Hour�, by ThinkFun Inc.

The objective of this puzzle is to help the red car get out of the traffic jam by moving the surrounding vehicles out of the way. The vehicles can only move forward and backwards. Cards are required to know the initial placement of the vehicles. Normally, when you purchase the game, it comes with a set of cards. You may also buy "expansion packs", which are simply sets of cards with different puzzles. For this project, you will need one of these expansion packs.

An online version of the game can be found here if you are not familiar with it: Car Game

In the end, I went about $0.50 over budget, but I don't think anyone will mind. The final product can be seen in the image below. The red car is the one you have to help escape from the traffic jam. The blocks have a slot down the centre that allow them to only move in one direction: up/down or left/right.

Step 1: Getting the Tools/Materials

Here is a list of all the tools and supplies you will need throughout this project.

-Flat File (hand tool)
-Miter Saw (electric or otherwise)
-Flat Head Screwdriver/Chisel
-Hand-held Rotary Tool (with cutting discs)
-Small Paintbrush
-Cutting Knife (Pen Style X-acto Blade)

-Wood: 12' of 1/2" x 1/2" (wood for board)
-Wood: 4' of 3/4" x 7/8" (wood for vehicles)
-Wood: 3' of 1" border/edging (anything that looks nice will work) (wood for border)
-Wood Glue
-Small Nails (8)
-Wood Filler/Plastic Wood
-Deck of RushHour Cards
-Paint (various colours)

NOTE 1: The 3/4" x 7/8" piece of wood I used was from a scrap pile. I don't think that this is a standard size that is available, but a 1" x 1" piece can be bought and sanded down a bit so that the pieces fit properly on the board.

NOTE 2: The lengths of wood above do not account for mistakes you may make throughout construction. I suggest you have a little extra on hand since mistakes are bound to happen.

NOTE 3: Whenever you use any of the electric tools, please be sure to wear eye protection. The electric miter saw often sends pieces of wood flying, especially when cutting smaller pieces. The cutting discs for the rotary tool can also break and send shards flying.

Step 2: Cutting the Wood

While we have the miter saw set up, we might as well get as much of the cutting done right away. There are two sets of pieces to be cut: the pieces for the board and the pieces for the vehicles.

The board is built with blocks from the 1/2" x 1/2" piece of wood. The following lengths must be cut:
-7 pieces 6 1/4" (6.25") long.
-36 pieces 7/8" (0.875") long.
-42 pieces 1/2" (0.5") long.

The vehicles are built using pieces of the 3/4" x 7/8" stick of wood.
-12 pieces 1 3/4" (1.75") long.
-4 pieces 2 3/4" (2.75") long.

The border will be cut once the board is completed since it will need to be cut to fit the board after it is glued together.

Note: When cutting the pieces, I found it was best to use a scrap piece of wood underneath the piece to be cut to act as a support. By doing this, the small pieces being cut were less likely to get caught on the saw blade and sent flying. Of course, wear your eye protection when cutting these pieces. The wood can be thrown at high speeds from the saw.

Step 3: Building the Board

Gluing the Blocks Together
While gluing the board together it would be best to clamp it all together, but I did not have clamps that were sufficiently large, so I had to hold them together by hand until the glue could hold the pieces in place.

The board consists of alternating 6 1/4" rows and composite glued rows. The composite rows each consist of seven 0.5" pieces and six 7/8" pieces (alternated). I recommend first gluing a complete composite row together, and then gluing the row to the longer 6 1/4" piece. Align the top of all of the 0.5" pieces to the 6 1/4" pieces. The 7/8" pieces should all be aligned to each other, equali height above the 0.5" and 6 1/4" pieces. Don't worry about the bottom, we will fix it up later. Sandwich the composite row with another 6 1/4" piece all glued together. Let the glue dry a bit before adding the next row. Once the glue is set, add another row, making sure it is properly aligned by using a scrap 1.5" x 1.5" piece as a guide between the pegs. Repeat until all six rows of six pegs is completed, like in the image below.

Trim Excess
The spacing left around the outside of the pegs should only be 0.25", instead of the 0.5" that separates the pegs from each other. Therefore, the outside of the board must be trimmed using your miter saw. Make sure that the glue has had a few hours to dry before you try to cut the board since a lot of stress will be put on the glued joints. I didn't trim this quite enough, so I had to add little spacers made from wood paint stirrers cut to size, but I wouldn't recommend this. It is best to cut it to the appropriate size right away.

Cleaning up the Board
Now that the board is all glued together you will probably notice that everything is not perfect. It's time to fix up any imperfections. First, fill in any cracks and gaps with wood filler. Once the filler has dried, sand down the excess filler and all edges on the front of the board. Any bumps on the board must be smoothed out or else they will inhibit the pieces from moving easily. Try to sand with the grain of the wood as much as possible to make a nice finish.

Smoothing out the Bottom
At this point, the bottom is probably quite bumpy. Flip the board upside down on a towel. Sand the bottom with coarse sandpaper to remove the worst of the bumps. The bottom does not need to be perfect, you just want it to sit level on a table.

Step 4: Making the Vehicles

I suggest first starting with the larger vehicles, since if you make a mistake on the piece, you may be able to recover part of it for use as a smaller vehicle.

Marking the Blocks
The blocks must first be marked with a tracing line. Line up a scrap piece of 1/2" x 1/2" in the center of the wide side of the 3/4" x 7/8" pieces of wood cut previously for the vehicles. Trace a line on both sides to indicate where the track will be.

Cutting Out the Slot
Clamp down one of the blocks and cut along the line with your cutting disc. Once both sides are cut, you can stand the piece up and break out the center piece with a flat head screwdriver and a hammer. You can leave a little more wood on the piece than you need, the excess will be sanded/filed off. Be careful not to split too much off. Splitting the wood can also cause the whole piece to crack. I ruined a couple of pieces doing this, but luckily I had wood to spare. If you have a good router available, I suggest trying this first since it will probably save you a lot of time.

Making the Groove Fit the Board
For the pieces to move smoothly, the slot cut out of each vehicle must be wide enough to allow a little wiggle room, the inside must be smooth, and the slot must be deep enough so that the pegs of the board do not touch the piece. First, get the general shape you want with the file. Match the piece to the board to see how it fits. Once the slot is about right, take out the sandpaper and smooth the inside of the slot. I found it useful to wrap the sandpaper around a piece of wood when sanding the slot.

Smoothing the Edges
Once the slot is ready, you need to remove all edges from the piece. This can be done with sandpaper or a soft file. Make sure that you also get the inside edges around the slot. The corners on the bottom of the pieces should be sanded to a curve, as seen in the image below.

Once all of the blocks are prepared as described above, they must then be painted. Any colours will work, but I suggest you do one the colour of the primary vehicle in the deck of cards. In the original game, the main car is red, in the fourth expansion deck, the primary car is a yellow cab. Once painted and dried, the pieces can be varnished and lightly sanded.

Step 5: Adding a Border to the Board

Cutting the Border
Once the board is built, a border must be added to keep the pieces on the board. Anything about an inch wide and not too deep can be used. Number each side of the board. Measure each side and cut the the border pieces with a 45 degree joints to connect them nicely together. Make sure to number the border pieces to match each side of the board since each side will be slightly different. The board will not be perfectly square and each side of the border must be measured and cut separately.

Adding an Exit Door
Line up the border to the right hand side of the board. Mark the center of the wooden peg third down from the top right on the border. Make sure to mark the height of the board on the border too. A 1" slot will be cut from this border. Using a ruler, measure and trace the shape of the section to be removed.

Cut two slots using your miter saw on both sides of the exit door. Remove the remaining piece of the door with a cutting disc in your hand held rotary tool and a cutting knife. Smooth the edges with sand paper or a fine file.

Mounting the Border
Now it's time to attach the borders to the board. The borders will be glued and nailed in to place to ensure that they hold together. Before gluing anything, hammer the nails partly in to the border. Next, apply the wood glue to the outside of the board, align the border and nail it in to place. Repeat for all four sides of the board. Make sure you also place glue on the joints between the borders.

Finishing the Board
Now that the construction of the board is complete, you can varnish it. Do at least two coats since the first will mostly be absorbed into the wood.

Step 6: Conclusion

Once completed, the game should look something like the photo below. If you prefer to be a little more creative, you can try designing the vehicles with a little more shape or paint a custom design on each, but it took me so long to just do the simple blocks.

Finding Levels:
For additional puzzle levels, you can buy additional sets of cards, or try searching the net for programs that generate levels for RushHour. The photo below shows a very simple puzzle that should not take too long to solve. There are many more difficult levels out there that can take you quite a while to solve.

I hope you enjoyed this instructable. It is my first, and I hope it isn't too awful. Please feel free to leave comments. If you feel anything is missing, I will do my best to fix it. If you end up building it, I'd also like to hear, so please leave a comment on your experience or any improvements you might have.

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