The Chinese SN series is REALLY GOOD. There's a 25mm, 50mm, 75mm, and a new 110mm. Also one that was like 8mm, but I can't find that one.

I am certain these parabolic profiles are MUCH better than the Dust Deputy stuff- that was an old profile that they moved away from years ago. And they're CHEAP!

https://www.aliexpress.com/item/1005...archweb201603_

Two design questions- one, positive pressure or negative? Honestly, negative pressure is a MUCH better idea. It can't leak, and you keep debris out of your impeller that can sometimes do some real damage. It also opens up a whole new world of advanced impellers that work much better but cannot handle debris. But you need a can (not a bag) that can take negative pressure and may need a relief valve to avoid collapsing it if the inlet is blocked.

Second question is multiple small cyclones (like a Dyson Vac does!) or one large one. The two certain things is that a big diameter cyclone is less likely to get something stuck in it, but it's taller, and taller is sometimes inconvenient. Splitting up among smaller cyclones can be shorter.

I am unsure on this, but I think that you do get better separation with multiple small cyclones. I did see a study showing that you typically get better separation and lower pressure drop (higher flows) by running the air slower. You can scale that by clustering smaller cyclones like the 50 or 75 on a lid.