Anyone build a mini-cyclone?

[Dan Friedrichs]

I'd like a mini-cyclone for my shop vac, but am disinclined to do business with Oneida. I've seen a few people build their own - has anyone here done it? Do you just use Bill Pentz's spreadsheet and specify a small (~6") drum?

One of the builds I saw appeared to omit the air ramp. Is the air ramp necessary?

[mreza Salav]

Here is the one I built from Bill Pentz plans:

http://www.sawmillcreek.org/showthread.php?t=105916

It is 6" on the main cylinder. I used the air ramp. Did it as a practice
to see if I want to build the larger one. But after it was finished I realized how
it works! GREATT!! and its one of the best shop builts I have done.
Very little dust accumulates at the filter, but only things that scape
are some of those very thing hand-plane shavings.

[Alan Schaffter]

One note about reproducing the BP design to make a mini cyclone (and a large cyclone for that matter) is that the dimensions for the spiral inlet ramp are a mathematical approximation. You can't generate a helix shape from flat material. It doesn't require too much effort, but you must warp the plastic or metal to achieve the helix shape. In case inquiring minds want to know.

[Dan Friedrichs]

Mreza, that's an amazing design! I can't believe I missed your post on that when searching, earlier. I intend to do my best to copy your design exactly My shop vac has a detachable motor, though (so you can use it as a leaf blower, etc), so I may need to do a little creative modifications. Thanks for the link!

Alan, I had to think about that for a second, but understand what you mean, now. One of the other mini-cyclones I saw someone build omitted the air ramp, and I recall reading some older discussions about the need for an air ramp in a full-sized cyclone, too. I'm curious how important it really is...

By the way, Alan, I saw the pictures of your mini-cyclone and shop vac setup, and that's what inspired me to build my own. I want to use a HEPA filter in the shop vac, but think it will foul too quickly without a cyclone ahead of it.

[mreza Salav]

Glad that my link was useful Dan.

Alan, you are right about that the ramp will not be a snug fit (and BP points this out on his webpage too). But this approximation is good enough and works well (at least worked well in my case).

My understanding is that the air ramp helps a lot to create the "cyclone" that will cause most of the dust to really drop in the bucket.

[Alan Schaffter]

The sloped inlet and the spiral air ramp (and the "neutral vane" that preceded them) help the incoming air from striking the central tube, prevents any air from going the wrong way around, and prevents the swirling air from striking the side of the incoming air after one rotation- the purpose of all this is to reduce turbulence and improve the cyclonic flow and particle separation.

[Alan Bienlein]

Here is another version I built last year.
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