Several designs were drawn and built to arrive at the final version for the project and I am sure it could still be improved. Early versions were built with so many connectors that the cart became too bulky and heavy (pics of these earlier prototypes are included at the end of the project). The final version allows it to be driven into our classroom and into our elevator while still being able to carry a reasonable load. Although 1"
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PVC was used throughout to provide strength and stability 3/4" may have been sufficient. Most cuts were made using an inexpensive hand miter saw and box available at Harbor Freight.
The main axle consists of the metal axle from the wheel being sent through a 3/4" plug which was drilled to allow the metal axle from the wheel to pass through. A bolt was attached to the plug before it was inserted into a threaded 3/4" reducer that slides right into a T connector on one side and an elbow on the other, as shown in the above picture. A 1" cross connector connects the two wheel assemblies making a complete stable axle. Two inch pieces of 1" PVC typically work well to join connectors without leaving a gap. This main axle was glued using the typical purple primer and then clear PVC cement.
The main frame consists of two sides built intentionally to be able to be disconnected from the main axle to give the project some versatility in case someone wanted to build an alternative front end or back end.
The standing area back end is shown above with several of the dimensions listed. The center connection is approximately 10" and had a mistake in it so there is an extra in-line connector that fixed a problem. This end went together pretty rough when we went to the permanent gluing stage so be sure to check your shape before gluing and use our numbers loosely.
The 3/4" wood was attached with 1" connectors found in the electrical department of Home Depot. The swivel wheels were added under the plywood and provided much of the strength to the cart allowing me to put my entire 195 lbs on the cart. Make sure the swivel wheels have clearance as they spin and don't make contact with the PVC. The edges of the plywood were routered to give them a cleaner finish. The red front end plywood sheet was a complex cut using a variety of tools including a drill with a hole saw bit, a band saw and a Dremel to clean up the corners.
The front end was done similarly with the dimensions as shown. The front and back plywood pieces were painted with a Tempura paint which was all that I had available from the art department but gave it a cool look. I coated it with several coats of clear Varathane Spar Urethane to protect it. The 3" swivel wheels seemed to fit better on the front end giving the whole cart a slight downward slope.