There's no way a shop vac can function as an adequate dust collector. It simply won't move the volume of air necessary. Shop Vacs are designed to make, well, vacuums while dust collectors are designed to move large volumes of air. Take a look at the examples of dust collectors at the Frame Outlet's Backroom Gallery on our web site: fwfo.net. Especially the picture of the Frame Square's dust collection. And even with powerful collectors, we don't get all the dust. But we get enough that we don't have to ware dust masks.
There's no reason to but a cyclone device between a shop vac and a saw it's collecting from unless you expect to pick up chunks of woodand vven then it's not necessary. The only advantage is that you'd not fill up the vac's canister and filter as quickly. It would actyally cut into the small volume of air that a shop vac's capable of moving.
