Funnily enough I investigated something similar to what you are planning a while ago, gave it up but here are some points that may be useful to you.

Remember that as you go around a corner, the outside wheel travels further than the inner wheel. This obviously causes problems with a single axle configuration. There are two ways to get around this,

1) Use a differential - expensive, heavy and not really viable

2) Use the same method as a go kart. A go kart has a single axle across the back. When it goes around a corner it is light enough and powerful enough to spin one of the wheels as it goes around the corner. This does mean that your tyres wear down quicker but the saving you make on a diff makes it worthwhile.

As for the axle itself, you can get a hold of some light aluminium hollow axles on ebay. I have just bought a solid steel one for the front of my new heavyweight for a fiver plus a few quid for delivery.

Good effort on the mill! Looks exceptionally impressive.

(Message edited by typhoon_driver on March 18, 2007)