those lids work for DC; I doubt they would work with a Shop Vac. I use one with
a 750CFM DC and it does cut down the efficiency, but it more than makes up for
that by preventing clogs at the impeller or anything nasty slamming into said
impeller. Plus it's way easier to dump the trashcan than it is to dump the
lower bag of the DC. It should get MORE than 90% of the dust. I hardly ever have
to empty the bag in the DC.

David wrote:

I saw in the Lee Valley catalog where they have a lid that fits on a garbage
can (for 29.95). It shows a hose coming from your tool to the can and
another hose from the lid going to your shopvac. It is suppose to collect
90% of the planer/saw dust in the can first before it goes into the vac.
Do any of you have an opinion if these lids really work? I don't have the
room for a big dust collection system.
Thanks for your opinions.