Hoist the motorcycle up onto the jack lift so that the bike is off the ground and you can easily access the wheels.
Remove the castle nuts from both sides of the rear axle--from both sides of the tire--with a crescent wrench. Place them off to the side for now. Once the nuts are off, slide the wheel forward slightly so that you can remove the chain from the sprocket. Pull the loosened wheel off of the swing arm on the rear of your motorcycle, then pull the axle completely out.
Determine the width that you want the rear of your trike to be. Most trikes have a rear that is half as long as the length of the bike, which means that you will have to measure the length of your bike and divide in two.
Measure the length of your existing axle. Once you've determined how wide you want your rear tires to be from step 3, subtract the length of your existing axle from this length. This will give you the total measurements of spare steel rod that you need to add to your existing axle. This will need to be divided in half so that you can add an equal length of steel to each end of your existing axle. For example, if you want a 3-foot-wide wheel base at the rear of your trike and you already have a 1-foot axle, then you will need 2 feet of steel. This 2 feet of steel will need to be cut in half, and 1 foot of steel applied to each end of your axle.
Use your lathe to turn the two steel rods down to their necessary thickness and length. They need to be exactly as thick as your existing axle, and the cuts need to be perfectly square. If you have a cut that is at a slight angle, then your bike will be poorly aligned, which will be a hazard to you while driving.
Weld each piece of steel onto the ends of your existing axle. Make sure the welds are perfectly square, as, again, if you have misaligned wheels, it can be very dangerous for you. Weld carefully and securely, making a long, straight rod/axle.
Weld the wheel hubs to your newly constructed axle, making sure they are square to the axle. Once welded in place, slide the new axle into the swing arm. Use the crescent wrench set to tighten the castle nuts. Place the chain back onto the sprocket as you do so, and before you tighten the nuts all the way. Finish by tightening the nuts and securing the axle in place.
Place your trailer wheels or whatever wheels you choose to use for the trike--just make sure they fit the hubs--onto your wheel hubs and tighten the lug nuts into place with either a lug nut wrench, or a crescent wrench set. Tighten them into place as snug as you can. Once they are in place, your trike is complete. Take it out for a test drive and enjoy your new trike.
