| Looks nice, Morris. I'm wondering if you extended the exhaust | through the lid inside by a few inches if it would help separation | would be the only suggestion. Might reduce direct path from inlet | to outlet.
Thanks! I've wondered about that, too. I thought about gluing the other half of the inlet to the underside of the lid - but decided to see how it worked in the most basic, simple configuration first.
To give credit where credit is due: I purchased two of the clear plastic cyclone separator lids from Lee Valley a few years back and have been very well pleased with their performance on 55-gallon barrels. I have actually spent a small amount of time (probably a grand total of 5 minutes) watching the "action" as the ShopBot carried out routing operations. If interested, you can see the 'Bot dust collection setup at the link below. Anyway, the clear LV lid does an excellent job of showing what happens inside the drum:
The air (with debris) enters and the chips spin fairly close to the drum walls all the way down. The debris on the bottom tends to form into a comma (',') shaped pile with the fat part of the comma close to the wall and the end of the tail near the center of the drum. The air currents in the drum continuously slide chips from the windward side of the comma-shaped pile to the leeward side, so the pile rotates slowly in the direction of the airflow. My impression (as a one-time desert-dweller) is that the pile behaves exactly like a sand dune and has exactly the same transverse cross section (convex on windward side with a flat slip face on the leeward side).
As with a real cyclone (I've experienced once in an F4 and hope never to repeat!) the center column is a low-pressure vortex of essentially clear air. Any debris that exits the top of the center column comes from the pile at the bottom of the drum - not from the intake opening.
Debris that travels to the Shop-Vac would seem to indicate that either the drum needs emptying or that the drum wasn't tall enough in the first place. I don't (yet) have a good handle on what the actual drum proportions might be for optimal operation, but the 55-gallon duo that I have on the 'Bot work /very/ well. This smaller unit appears to work well, but I don't have much experience with it yet and, to tell the whole truth, I don't really have much time to tinker and tune.
I have no clue as to whether the direction of rotation is important or not. Builders in the southern hemisphere may get better results by pointing the intake block the other way - or it may just not matter at all...
-- Morris Dovey DeSoto Solar DeSoto, Iowa USA
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