This was my “out of the box” solution. I finally got fed up with the mess from my Harbor Freight dust collector. After I originally got the HF, I replaced the upper bag with this POWERTEC 70001 Dust Collector Bag https://www.amazon.com/gp/product/B005VSAP74/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
. It helped quite a bit. As I used it for a couple of years, it became more of a pain. It was always leaking dust and was only passable at capturing dust. It originally was only connected to my CNC. Then I added a drum sander. It handled the intake OK, but the filtering was now marginal.
I decided to make it 2-stage. Option 1 was to make a Thein baffle, and option 2 was "off the shelf". Since this was the middle of November, and I had umpteen Christmas projects due, I decided on Option 2. I didn't have the time to tune a new dust collector, even though it looked like a fun project.
Either way, I had decided on replacing the upper bag with a Wynn Environmental filter. https://wynnenv.com/woodworking-filters/
The Wynn install was really easy, and the performance is great. Lots of info and ideas on their web site.
To match it up, I decided on the Oneida Air Systems - ONEIDA AIR SYSTEMS 4" Super Dust Deputy Deluxe from my local Woodcraft. https://www.woodcraft.com/products/oneida-air-systems-4-super-dust-deputy-deluxe?via=573621bd69702d0676000002%2C576455d369702d2f2f0013a2%2C5764562369702d3c42000be9
They had one in stock and it seemed to take 'normal' 4-inch dust fittings. The cyclone about the same price everywhere, and available on Amazon.
I am extremely happy with the setup, and time will tell if that changes. I empty the drum about once a week. It has a few inches of wood dust and chips in it. I figure that keeping the dust level as low as possible should work the best. The lower bag barely has a dusting in it, even after 3 weeks. I was unsure if the cyclone would grab much of the dust from the drum sander. It does a great job. I think the long neck on the cyclone helps quite a bit with containing the dust.
The bottom line is that I can now work in the shop with the garage door closed and still breath. Things actually went as planned....