With the dust of concrete and sawdust blocking up the fitters on vacuums. A few of the lads have made a some of fitter. Seen this one, thinking of getting it or is it worth making one? http://www.pwm-sales.co.uk/Details_options.asp?ProductID=132
I use a pre seperator. Only get a tiny bit of dust in the hoover but its so fine it goes through the bag and filter and into the motor. Suction drops after 10mins or so. Need a vacuum with better filters - M class or H (hepa). Looking for one myself at the mo. Can get festool midi for £200 but can't find anyone that stocks hepa filters anymore