Step 1: Take Measurements
The author measured the user’s trunk area.
Step 2: Cut the board, add casters
Cut a piece of ¾ inch plywood to the dimensions of 8 inches x 16 inches.
Next, cut a 45 degree chamfer on each of the corners for a rounder look.
Round all the edges; this will be easier both on the kid and the upholstery.
Position four casters on the board (in this case, I aligned them on the corner bisectors on a whim).
The main point here is to try and position the casters so that the radius of revolutions does not touch - you should be able to spin the casters without them banging into each other. The other point is to spread out the load as uniformly as possible.
Drill pilot holes for the casters, and then screwed the casters into place.
In this case, I used a 7/64 inches drill bit for the pilot holes, and used #10 - ½ inch metal screws to attach the casters.
Collect good casters for such projects. Whenever you see furniture in the process of being disposed, (i.e. desk, chair, etc.) with casters, try to rescue the casters before the rest of it goes to the dump. You can also buy casters online, at the hardware store, etc. I am experimenting with using ball transfers as casters for scooter boards.
Step 3: Upholster the board
Lay out the scooter board on top of a piece of foam padding. Lay the board and the foam on top of faux leather or other upholstery fabric. The foam should be bigger than the board on all sides, and the fabric should be bigger than the foam. This gives space for the fabric and foam to wrap around the edges.
The wheels are on in this step because the wheels all need to spin freely. With the wheels attached, this can be easily tested.
Wrap the fabric and the foam around a straight edge. Staple into place. Repeat on the opposite side, stretching the fabric tight; staple into place. Repeat for the other sides, and then start on the corners.
Trim the foam and the fabric as needed. The corners are especially tricky. The author used the corner technique from http://littlegreennotebook.blogspot.com/2012/07/how-to-upholster-bench-corners.html
Step 4: Attach Velcro
Cut straps of Velcro long enough that they can secure the child onto the board. Make sure that the hook (rough) side of the Velcro points away from the child (no accidental scratches). Make sure the loop (soft) side of the Velcro is turned the right way so as to mate with the hook Velcro.
Also on this step the author added a stabilizer bar. Normally this is not needed; most children have more arm and leg and can right themselves if they tip. For this project, the user needed a little more help - he could tip over and not be able to get back upright. The bar can be removed once he learns to balance by himself. Think of it as a set of training wheels.
I think the stabilizer bar used to be a sign stake or a tomato stake (i.e. scrap wood I had on hand) that was rounded and sanded smooth so he wouldn't scrape himself.
Step 5: User Testing
1) He is top-heavy. Since he is missing some leg, his head is the heaviest part of him. If he is positioned so that he can reach the ground, he tends to nose-dive. He figured out how to balance, and was able to move with his back wheels and feet in the air (like a wheelbarrow). We will fix this by adding a nose wheel to prevent tipping.
2) It would be easier if he had more use of his arms. We will fix this by making a tapered nose on the next model.
Step 6: Version 2 Cutting
The new board is 8 inches x 21.75 inches. It has a tapered nose to help him move his arms, and the extra length will give more stability.
The desired shape was mapped out, and marked off 1 inch from the edges for upholstery. The rotation of each wheel (except for the nose) is marked. The board is cut, the holes are drilled, and the casters are attached. I had initially considered a smaller wheel for the nose, but later decided to make them all the same size. I used the same size bits and screws for this build.
Step 7: Version 2 Upholster
This time, the fabric was tucked under and stapled through both layers. It results in a much cleaner look. Pull the fabric tightly before stapling the material.
There was extra padding in the nose and on the tail; these areas most likely to be involved in collisions.
Step 8: Version 2 Velcro
Just like before, Velcro was attached so that the user can quickly be strapped onto the scooter board.
The stabilizer bar from the first model to the second was moved and used for this project.
Step 9: Try out the product.
Step 10: Update: Ball Transfers
Ball transfers work great as casters! The ball transfers bought from Amazon are very smooth - they run in any direction and don't bind. The disadvantage is that they are considerably noisier than office chair casters, especially on tile and hardwood floors.
They can mount from the bottom of the deck (like the casters). Since there are no swinging parts, we don't have to worry about a radius of revolution like with the casters.
The best part is that they can be mounted from the top of the deck. This means cutting a hole through the wood, then screwing the ball transfer into the top of the wood deck using the provided mounting holes. This dramatically lowers the height of the scooter board. For someone with poor leg and arm length like the user for this project, this means the legs and arms are closer to the ground and thus more useable. For this design, hugging the ground also removes the need for an anti-tip measures. It becomes impossible to tip as the scooter board rides ½ inches from the ground. The author ensured that the upholstery was nice and tight to prevent it dragging on the ground.