How necessary is DC ring and plastic bag?

[aaron_t]

I have the option to purchase a 2hp motor with 12" impeller attached for a good price.  The rest of the dust collector is long gone. 

My thought is to build a Thien top hat separator over a garbage can, direct mount the motor and blower atop the separator, and plumb the output of the blower to a Wynn filter.  The filter would hang down from a fitting on the blower output. I would add a cleanout pan to the bottom of the filter.

Compared to the setups I have read about this one would not have an OE dust collector ring with plastic bag hanging below.  I'm wondering how necessary is this second point of separation?  I guess it comes down to how efficiently the separator performs.  With high efficiency there should be little dust making it to the filter.

Can someone quantify how much dust they end up with in their plastic collection bags in what I'll call the "normal" setup?

Thanks in adavance for any input / advice.

[Bulldog8]

Well in my case all of the dust was either separated into the collection barrel or ended up in the filter. Nothing remained in the plastic bag. I changed from a filter bag set up to the Wynn and plastic bag and found the increased air movement was really loud. So after seeing that no dust ever went to the bag, I closed the bottom of the filter housing as shown. There is still a bag in there, it's just shortened and rolled up. I open the bottom and let the bag hang down to collect the fine powder dust when cleaning the filter.

Steve

[tvman44]

I vent mine outside. :)