I used the Harbor Freight 8" (or 10"?) pneumatic full swivel wheels and mounted them to a 2x6 frame with plywood top. Next time, I will use just one pair of full swivel casters and one fixed set. It seems that with four swivel tires they compete against each other and it's hard to push around. The good thing is...with those tires I can roll it outside onto the gravel drive and do the grinding, sanding, and dirty dusty work; blow it off and then bring it back inside the shop.
