A dust collection system for portable sanding or grinding equipment employs a cyclone separator mounted directly on the tool or machine, with a dust outlet duct at the narrow lower end of the cyclone, and a cartridge air filter mounted on the top of the cyclone. The filter returns the air flow from the machine to the ambient air in the vicinity of the tool. The dust is concentrated in the cyclone, and a small volume air flow then moves the dust through an elongated flexible hose or duct to a remote dust collection station. An air pump at the remote dust collection station provides sufficient air flow to draw the small volume of air plus entrained dust from the tool-mounted cyclonic separator. A cyclonic separator at the remote station separates this dust from the air flow and deposits it in a collection tank or drum.