Block Basics

I discovered “unit blocks” (also known as “kindergarten blocks” or “standard unit blocks”), a standard block size invented in the early 1900s by Caroline Pratt, an educator who refused to patent the design so that they could be shared freely by all. The basic design is based on the ratio of 1:2:4, typically 1 3/8" x 2 3/4" x 5 1/2". All blocks in a set are based on multiples or fractions of those dimensions, so they fit together.

I have provided a selection of unit blocks here to get you started, but a quick search online will provide you with many more shapes, all based on these unit-block dimensions. By working with these standard sizes, your blocks will work perfectly with other sets, and vice versa.

I didn’t need to do any research to know that children’s playrooms can become messy quickly, so I do like to provide storage for any toy that I design. In this case, I have designed a storage wagon in the shape of an old-time race car to hold all the blocks. Simply fill it up and roll it away under the bed when you’re finished.

Building Blocks

The thickness of these unit blocks provides a bit of a challenge when choosing your material: you will need to start with 6/4-thick rough wood. I chose hard maple, which, along with beech, is the recommended species for toy blocks. It may be tempting to pick pine, since 2x4 lumber is so easily available, but I encourage you to stick with maple or some other tight-grained hardwood. Maple is solid and sturdy, which allows children to build tall, stable structures. Maple also machines cleanly and does not splinter easily.

Start by jointing your lumber and planing it to the required
1 3/8" thickness. Next, lay out the blocks to make the most efficient use of your wood. The dimensions of the individual blocks are noted in both the parts list and on the plans. Refer to these measurements as you cut up
your stock.

As well, now that your wood is planed, it’s a good time to finish-sand the faces of your boards. It’s easier to do so now, when you have one or two large boards, as opposed to at the end, when you will have dozens of small blocks that need sanding. You’ll still need to sand the edges then, but at least you have a head start with sanded faces.

For a guide to building each block type, see “Block by Block”.

Round and round

After cutting out your blocks, turn your attention to rounding the edges. Maple machines very nicely, leaving lovely, crisp corners, but these can be sharp. You need to round over all the edges and corners for safety and comfort. This process can be done using a block plane, sandpaper or by setting up a roundover bit in your router table. If you use the router table, be careful, as you are working with fairly small pieces of wood. Use a fence, keep the router bit mostly covered by this fence, take your time and rout carefully. The rounding process can, unfortunately, become very tedious, as you have to smooth every single edge—eight passes for just one rectangular block. I repeat: take your time and be careful. It might be a good idea to spread out this work over several sessions instead of getting bored and inattentive.

After rounding over the edges, break out the sandpaper and smooth all the faces of the blocks. Your goal is silky smooth blocks that feel great in your hands and contain no splinters or sharp corners. I chose to leave my blocks unfinished, so I was extra careful during the sanding phase. If you choose to finish your blocks, make sure that you leave plenty of time for the finish to cure, since they will be piled closely together most of the time, which will restrict further curing severely.

Load ’em Up

If your children are like mine, cleanup time is not a popular event. So, when building a toy, I try to provide a box or some kind of storage. With this project, I went beyond a basic box: I stretched the ends, cut a silhouette and added some wheels. The result is a race-car storage box, which can be a toy unto itself.

Start by cutting out the pieces for the race car’s sides and ends. The top edge of the front piece will be bevelled to match the slope of the sides, so for now, just rip it roughly 1/8" wider than necessary. Also, as you read the next section, refer to the plans regularly to see all the details and how they work together.

Mark a line 2" in from each end of the two sides, on their inside faces, and then mill 3/8"-deep dados along those lines. Use the actual front and back pieces to determine the width of the dados for the most accurate joints. Since I needed only four small dados, I made these by taking repeated crosscuts with my tablesaw sled, using a normal blade. This process is a bit repetitive, but for a small job such as this, it’s quicker than setting up a stacked dado blade.

Next, cut a rabbet along the inside bottom edges of all four pieces to accommodate the bottom panel, as shown in the plans. The rabbet needs to stop at the dados in the two side pieces. I find that using a straight bit in the router table is the simplest way to perform this step. First, set up your router table with a straight bit and a fence. Make a few test cuts in scrap, to set the 3/8"-wide cut. Run a full-length rabbet along the inside bottom edges of the front and back pieces of the wagon.

For the rabbets in the bottoms of the two sides, things are trickier because these grooves need to start and stop at the dados in the sides. You’ll get the best results if you mark your fence with a pencil showing the point at which the left and right sides of the bit emerge past the working face of the fence. You’ll use these marks in a minute to help you start and stop the router cuts in the right place.

Next, orient the bottom edge of one side piece toward the fence, with the right-hand end angled away from the fence and the left-hand end touching the fence. Slide the workpiece so the left-hand dado is lined up with the router bit, switch on your router, and then ease the right-hand end of the piece against the fence so the entire bottom edge of the side is touching.
Since you are starting at the dado on the left, the bit will probably not make contact with the wood. That’s what you want. Continue by sliding the board along the fence to the left until the bit enters the second dado gap, but no more. The pencil marks you made on the fence will help you do this correctly. When you’ve reached the point at which the routing pass must stop, simply turn off the router and wait for it to stop spinning before removing the piece. Repeat this process with the second side piece.

More bodywork

Cut out the shape of the race car in the sides of the wagon. You can get creative and design your own silhouette, or simply work with the one provided here. Note that I have designed this shape so that the toy blocks sit a minimum of 1/4" taller than the side of the race car, at the highest point of the sides, to make it easier for children to get their fingers on a block to pull it out.

Start by fastening the two sides together temporarily, inside face to inside face, using double-sided tape. This arrangement allows you to mark and cut out both sides at once, ensuring they are identical.

Measure in from the back end of the sides by 5 1/2" and 10 1/2" along the top and make marks at each point. These points define the front and back of the cockpit cutout along the sides. Measure down 2" from the top and draw a line across the bottom of the cockpit. At the front of the car, make a mark 1" down from the top, and draw a line connecting this mark to the 101/2" mark at the front of the cockpit. This line defines the slope of the hood of the car. Next, use a compass to draw curves to round over all the corners. All of the corners—the four outside corners, as well as the two inside ones in the cockpit—have the same 1"-radius curves. Set your compass, draw the curves and then take your temporarily joined sides to the bandsaw. Cut the rounded corners, then sand the edges smooth while they’re still together.

Pull the two side pieces apart, then dry-fit all parts. Remember how you made the front piece slightly wider than necessary to allow for a bevel on its top edge? Mark the 8° slope to match the sides. Next, set your tablesaw blade to a matching angle and rip the front piece to size.

While you’re at it, use this dry-fitting stage to measure the actual size for the bottom panel, then cut it out on the tablesaw. Finally, sand all the parts to 150 grit, then glue and nail the body together.


Fill the nail holes with wood filler, then perform your final sanding on the cart body. As with the blocks, sand all the edges aggressively to make them rounded and gentle.

Apply primer, then two or three coats of paint. I chose a bold racing-car red. Note that with certain bright colours, you will require a tinted primer. I was halfway through priming the project (with white primer) before I remembered this and switched to grey. The white primed section required a couple more coats of paint than the rest, so this is an important detail to remember.

Allow the paint to cure fully (place it outside on a sunny day to hasten the process) before moving on to the final step of installing the wheels and tow rope. I picked the largest craft wheels I could find, which were 2 1/2" in diameter. Drill two holes, 3/4" up from the bottom, centred in the dados on the front and back ends of each side. (The axle pins are long enough that the holes would otherwise extend right through the sides.) Apply a dab of glue inside each hole and fit the axle pins into the wheels, and then into the axle holes.

Now, turn your attention to the pull rope. Mark two points on the front of the wagon, 2" in from each side and 2 1/4" up from the bottom. Drill pilot holes and then install two screw eyes. Cut a short piece of rope about 24" to 30" long and tie it to the two screw eyes. I used 1/4"-diameter white nylon rope. This cord is far stronger than necessary, but I like the nice, thick look. The rope is attached to each eyelet with an alpine butterfly knot (also known as a lineman’s loop), which is both decorative and strong. Beware that cut ends of nylon rope fray quickly. To prevent that from happening, wrap the rope tightly with a piece of masking tape before making your cut near the tape. The tape will hold the fibres together while you light a match and lightly singe the cut end. The nylon filaments will melt together—and stay that way, even after removing the tape.

Now might be a good time to release your inner child and get down on the floor to build something. Of course, you will have to share your toys with your children!

Block by block


Here are some tips and tricks for creating the blocks in this set.

The rectangular or square blocks are straightforward to cut with a tablesaw or mitre saw. Rip your stock to a width of 2 3/4" and cross cut them to the desired length. Things get a bit more complicated when you start on the other blocks.

The small triangle can be cut out on the mitre saw using a simple 45° setting. For safety, you want to leave raw stock long and cut each block off the end one at a time. To avoid resetting tools continually, I set my mitre saw to take a 45° cut. The tablesaw was set up with a crosscutting sled to make 90° cuts. Both were equipped with a stop block clamped in place to ensure that the resulting small triangle was the correct size. Start with a long piece of 2 3/4"-wide wood and make a cut on the mitre saw. This gives you one small triangle block and leaves the end of your stock with a 45° cut. Then, move to the tablesaw and take another cut, which gives you a second small triangle block, leaving you with a 90° end on your raw stock. Each time you repeat these steps, you get two more of the small triangle blocks.

The larger triangle block has a sharper angle, which exceeds the abilities of my mitre saw. In this case, I found it easier to start by cutting out a unit block, and then bisecting it carefully from corner to corner on the bandsaw, leaving two triangle blocks. The resulting hypotenuses weren’t perfectly flat, but pretty close, and you can clean them up quickly with some sanding.

The small buttresses and the half-Roman arches nest together, as do the quarter-circles and the half-circle curves. As with the large triangles, each of these pairs is cut from a single block. A well-tuned bandsaw is probably the best choice for these cuts. I did try some cuts with a scrollsaw, just to see if it was possible. It was, although the machine did struggle, given the thickness of the maple.

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