Is there a minimum volume for the collection bin on a dust collector?

The taller it is, the better it will work.
It will collect no more dust than the bucket top vacuum would collect by itself, but you won’t have to empty the container as often.

For a vac, 5 gallon should be fine. The issue becomes how much debris you can collect before you have to empty (or clog up the system). If you do any power planing or something with a lot of chips, a 5 gallon bucket might last 2 minutes before it gets full.

-- Our village hasn't lost it's idiot, he was elected to congress.

Taller makes sense both in terms of a larger volume to fill before emptying, but also in terms of my understanding of how the Thien system works as there will be less turbulence in the bottom of a taller design. I wonder if I can cut the bottom off of a five gallon bucket and stack it on top of an intact one to improve the design?

-- Chris - Would work, but I'm too busy reading about woodwork.

If you can figure out a way to seal it completely, there’s no reason that won’t work. Most of them sit inside one another, so there might be a good sized gap unless you flip one upside down or something.

-- Our village hasn't lost it's idiot, he was elected to congress.

I have a 30gallon metal garbage can with a thien baffle. It does an excellent job until the debris get to about 6-8 inches below the baffle then material starts to carry over into my dust collector bag. Taller is better and also don’t have to empty as often. If you have a planer a 5 gallon bucket will fill within seconds.

-- Bruce, Boise, ID

What I have learned is that you can’t allow the separator can to even remotely come close to being full before it quits functioning. For my set up once the can is 1/3 full is where I lose performance. If that holds true w/ your 5 gallon bucket then you are going to have to empty it very frequently.

-- Bondo Gaposis