Cyclone Vacuum Separator

Spangler's cleaner, already published, pulls air through a bag: the bag is both the filter and the bin, so suction falls away as it fills. James Dyson, who had used industrial cyclones in a sawmill, put the same idea in a cleaner - and then a second, finer cyclone behind the first, so both grit and dust come out of the air before any filter. **US 4,593,429**, "Vacuum cleaning appliance", Dyson, filed 14. August 1984, granted 10. June 1986: a lower-efficiency outer cyclone and a high-efficiency inner cyclone in series, so "dust bags are not required". **You build the outer cyclone** from a bottle and pipe on a workshop vacuum, and weigh what it separates - sawdust and flour - to find where it stops working, and how far a home-made cyclone falls short of the textbook.