"Top Hat" dust cyclone

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Project by curliejones posted 06-16-2016 01:42 PM 3186 views 11 times favorited 6 comments Add to Favorites Watch

You’ve surely seen this trash can top separator before and I strongly recommend you simply start and work the details out as you go. Measure the trash can. Make a router circle jig. Cut a 5/16” deep dado 3/4” wide (or whatever your can lip measures) in 3/4 plywood. The plywood base in my separator was cut for a drop slot about 2” wide so that the sheet metal with a 1-1/8” slot would have lots of support, and yet have a sharp edge for separation of the chamber.
- I used sheet acrylic from a fluorescent fixture diffuser (free) instead of buying plexiglass. I used arcs from the cut plywood for a pattern to support the acrylic. Seal edges with silicone and seal to trash can with weatherstripping. This seemed best assembled upside down so the acrylic lip would not get damaged. I used a 45-degree 4” fitting for the inlet (not necessary, since a straight coupling would do but that’s what I had) and a 4” coupling for the outlet (to dust collector). I lined the “chute with 26 ga sheet metal, cut to fit and applied with silicone. I cut the sheet acrylic 9-1/4” wide, a random but educated guess after viewing others’ cyclones and let the acrylic extend into the can inside the drop slot. I notched the acrylic to 7-1/4” for the part not in the drop slot; that matches the wooden L-brackets that separate top and bottom. The plywood circle was cut 2” past the edge of the can dado to give me room to support and join the top with L-brackets made of wood and screwed into place. The acrylic sheet readily bent into the correct form and fit into rabbets where it met the chute. I supported the bend with a few arcs from the plywood cutoffs while the silicone dried.
In hindsight, I have read that the solid part of the circlular interior should be where the chute enters and the drop slot then starts to end at the far end and meet the short end of the chute. I failed there, but yet I get no dust build up at the far end of the circle (no slot), good cyclonic action, and almost nothing entering the 4” clear hose to the collector/vacuum. In the few tests performed so far, I’m getting NO SAWDUST visible in the short hose to the vacuum side.
My opinion is that it works like a charm with only a 1 hp Jet collector. For the cost of two fittings and a tube of silicone, I’m very happy with the protection offered to my DC motor and filter bag. Next I’ll build a wheeled platform for the can and the DC in case I want to move them assembled. Next up in the Clean Air Act of 2016 – a box fan frame with a good AC filter hanging from the middle beam! Thanks to Phil Thien for the baffle that has become so widely proven.

-- Like Guy Clark sez - "Sometimes I use my head, Sometimes I get a bigger hammer"

6 comments so far

View MilFlyer's profile


948 posts in 2962 days

#1 posted 06-16-2016 04:26 PM

You’re definitely right. I have been meaning to make one of these and I think I just need to get up and get to making. Thanks for sharing!

-- VR, Richard "Fear is nothing more than a feeling. You feel hot. You feel hungry. You feel angry. You feel afraid. Fear can never kill you"--Remo Williams

View kiefer's profile


5852 posts in 3957 days

#2 posted 06-17-2016 02:12 AM

I agree it’s a must have .
Nice build and they do work great except when planing plywood the shavings will plug it up.


-- Kiefer

View Dave Peura's profile

Dave Peura

42 posts in 3974 days

#3 posted 06-17-2016 08:38 PM

I also need to get off my rump & make one of these. Nice job building this, and great idea using the acrylic sheet

-- Dave Peura

View Billp's profile


804 posts in 5490 days

#4 posted 06-20-2016 08:14 PM

I made one of these and it’s one of the best things I’ve ever done. It works so good I have never had to empty the bag on my dust collector in over 4 years.

-- Billp

View Pointer's profile


465 posts in 2402 days

#5 posted 06-21-2016 02:17 AM

Definitely need to get me one of these. Thanks for sharing.

-- Joe - I am not entirely worthless, I can always serve as a bad example.

View rackjabbit's profile


53 posts in 3198 days

#6 posted 06-30-2016 09:36 AM

I was skeptical but these things work so well. I made one of these about 2 years ago and have not needed to empty my DC bag. I made mine out of old laminated counter top/ kitchen doors that I salvaged. It was the bin which cost the most in this project, but I needed one anyway. Again Thanks to Phil Thien.

-- Once the dust settles, breath and behold the beauty of the wood.

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