aloo! so, as a part time job, i strip floors, tiles...that sort of stuff. light scale demolition. its fun it can be a nightmare, navigating ten flights of stairs with a bag of rubble.... 170 times :jester: anyways, we grind concrete floors and all that too, make a complete mess. i look at the grinder hoods and the vacuums and laugh internally. the vacuums, well, they have lil "beaters" that knock the dust off the filters. great big filters. the grinder shrouds, expect air and grit to just do an abrupt right turn and squeeze out through a 30mm hole... we run 60mm hoses? obviously, we need dust masks and exhaust fans and all that for, when workin in enclosed rooms, its gets uncomfortable. well, i recently got in the destructive mood, and pulled the wall down between my shower and laundry. pulled isnt really the word. tapped gently and stood back is more apt its beeen needing work for a long time! so i started grinding the concrete floor. disc from work, no shrouds etc, i take my time on my own jobs. first few seconds, no way. this is just TOOOO MESSY. so i made a shroud. cool. it blocked my lousy wet and dry vac up in less than 15 seconds this dust is similar in grade to talcum powder. super fine! so i made a cyclonic seperator. and here in lies the marvel. i didnt really calculate the dimensions, just fudged a few numbers til inlet and outlets suited my hose diameters. ie, air speed and volume is basically an educated guess that i can only move so much air, take 10%, with a 1400 watt motor... and this thing works! its still too large to get the ultra fine dust out, but after half an hour of grinding, my hopper is full of super fine silt, and the the vacuum hopper is empty. the filter gets a thin layer of dust that does clog it, but...half an hour is a lot better than 15 seconds! my plan is to make four more cyclones, but only roughly 1/4 of the size. the smaller the cyclone, the smaller the particle removed. then all four in parallel will flow as much as the big one. the big one removes the majority of stuff, the four lil ones remove the rest. (they can easily be made to remove say, cigarette smoke sized particles) so i guess this thread, besides having a crow about myself, is to ask... what are peoples thoughts, feelings and experiences with the most famous of cyclone filters, the dyson? ive never owned one, used one, etc, but gee i love the ideas they use!