The above pictures are of a very simple vertical disk sander, that can be mounted on a workbench, table top, etc.. The base is constructed of scraps of angle steel for feet, with rectangular tube for legs. The motor is a 1/2 HP Harbor Freight special, but any motor of similar size and RPM (1725) should work.
The aluminum disk, was made from scrap engine parts, melted down and cast in sand. It was then machined on my Mill-Drill to 9 inches in diameter, approximately one inch thick. The hub is approximately 2 1/2 inches thick. The motor shaft is 5/8" dia..
I still need to cast and machine a table (the temporary one is shown), but so far it works like a champ. WARNING: It makes a ton of wood dust! So it will need to be used with a dust collector, respirator, or in the great outdoors (like I do)...