I recently added a dust separator to my shop vac, and it's been a very welcome addition! The separator directs most dust and small debris to a 5 gallon pail, leaving the main vacuum chamber (and filter) relatively clean. This prevents clogging of the filter, ensuring that suction is maintained and making cleanup much quicker and easier.
The dust separator I used is a Dustopper, which I purchased for two reasons. First, it was reasonably priced; about $40 at Home Depot at the time of writing. But more importantly, I was inspired by this video from John Builds It, showing how he built a frame that integrated the vacuum and and Dustopper into one:
It's one of those projects that I knew I was going to build as soon as I saw it! It wasn't long before I purchased a Dustopper of my own and started working out how to build my own portable dust collector like John did.
I already had a 16 gallon Craftsman shop vac, so my dust collection system is built on that. John used 2" couplers to attach the PVC pipe to his vac, but I found they were too loose to use on mine. Instead, I flared the ends of the 2" PVC pipes using a heat gun to make them fit tight to the base of the vacuum (Warning: PVC pipe can give off very toxic fumes when heated/burned, so extreme caution is necessary when doing this.)
I had some scrap OSB laying around, so I used that to make the top. The collection chamber is a standard 5 gallon pail which I already had. Some users report the Dustopper works best with a Homer Bucket but I've had no problems using a "generic" one.
The Dustopper only came with a single 90 degree adapter, so I purchased another one online. I couldn't find one that fit the Dustopper port, so I adapted it with a 2" PVC coupler and a small section of 2" PVC pipe. I flared both ends to make them fig snugly and glued it all together. The adapter is slightly restrictive and not very pretty, but it works.
I put the Dustopper through its paces, cleaning up debris around the shop and my drill press, and using it with the dust port on my router table.The proof is in the bucket, and so far the Dustopper has exceeded my expectations. It's picked up nearly all the dust and wood shavings as expected, but also leaves, packing peanuts and other bits and pieces. Hardly anything makes it into the vacuum itself! Since adding the separator I use the shop vac a lot more than I used to; it's much more convenient now that the filter isn't constantly clogging. The only downside is less power, but it hasn't been much of an issue given how I use the vacuum. Overall it's a win!