The wooden carts of the medieval era served many purposes: they carried produce and livestock to market, transported victims of the period's brutal plagues, and condemned prisoners to their executions. They were designed so that they could be pushed or pulled by human force, or hitched to oxen or donkeys to pull. Metal was too precious to use for joining parts, so mortise and tenon joints held the cart body together, while wooden pegs kept the axle from slipping out between the wheels. Here's how to make a replica of a medieval cart.
Cut all mortises and tenons as shown in the diagram that accompanies this step. Make all the mortises slightly tighter so that the tenons will fit snug. Adjust as needed until everything fits together well. It is easier to cut deeper and wider by sanding or grinding with a Dremel tool than to try to add stock back after it has been cut.
Cut the axle holes in each side of the cart, as shown by the black circles in the diagram in Step One. Use sandpaper to smooth away any burrs.
Apply carpenter's glue inside all the mortises and on all the tenons. Slip all pieces into place and press them firmly together. Wipe away any excess glue. Allow glue to dry overnight.
Apply carpenter's glue to entire surface of one side each of two of the 3-foot diameter wheels. Press glued sides together and clamp tight. Allow glue to dry for 24 hours. Repeat for the second pair of 3-feet diameter wheels.
Use a 4-inch hole saw to drill a hole through each wheel. Apply petroleum jelly to the surfaces of the hole. Slide one wheel onto each axle. Center the axle across the cart. Use a carpenter's pencil to mark the edge of the wheel on the axle. Remove wheels and axle from cart.
Use the 1-inch hole saw to make holes for the axle pegs. Slide the axle back through the cart sides and attach the wheels. Drive the axle pegs through the holes in the axle. Apply petroleum jelly to inside of axle hole and to entire axle. Slide your axle through the holes in the side of your medieval cart. Wipe away excess petroleum jelly with a soft cloth.
Test your cart to make sure the wheels turn. If they don't turn easily, remove pegs and sand inside your axle holes with a Dremel tool, reapply petroleum jelly, and replace the axle and wheels.