Cyclone Dust Collector and adding a baffle

[Carl Weber]

Hi All, new here but been lurking. I have a cyclone that I built (it is the one from Wood Issue 100). I have had it built for about 14 yrs and it worked great. It has not been in use for at least 11yrs (I built a new shop and just now getting to the full setup of the shop). I have a question on use of a baffle. I was going to add a cone baffle to the cyclone outlet pipe. Is this a good idea? Has anyone done this? Is it time to re-design the cyclone? Thank you in advance.

[Anthony Whitesell]

Do you have a neutral vane installed on the inlet pipe?

[Carl Weber]

No I do not. I built it per the directions. The Outlet pipe does extend to the bottom of the Cyclone Cylinder. Below is a graphic that is fairly close to what I have built.

[Anthony Whitesell]

First I would research the neutral vane for the inlet. I'm not exactly following how you want to modify the outlet. Could you modify the picture above to sketch your plan?

[Jim Andrew]

Bill Pentz has instructions on his website about building your own cyclone. Perhaps you could read up there and see if you missed anything. How did the system work when you had it running before?

[Bruce Wrenn]

Visit Wood's web site. There you will find info about neutral vane.

[Carl Weber]

Anthony, this is what I was thinking of adding.

Capture.JPG

[Carl Weber]

From what I remember it worked fine. But since I am moving it, I thought I would do a few upgrades on it. This would keep some of the finer particles from entering the outlet pipe too soon. I have another DC that I made from a pre made cyclone and it has this feature. I had to add a pre collector to it as the baffle that is in installed leaves a 1" gap between the baffle and the cyclone cylinder, which allowed larger chips to jam the DC.

[Phil Thien]

Bypass occurs when debris exits the outlet tube before having a chance to enter rotation.

Your proposed cone won't help much with bypass.

What your cone WILL do is break the vortex (the cones, my baffle, they're all technically vortex breakers).

The benefit of adding a vortex breaker on a conventional cyclone is a reduction in scrubbing, where already separated debris (down in the drum) is reanimated and given another shot at exiting the outlet tube. That is because the vortex created in your cyclone likely extends all the way down into the drum, where it likes to stir things up a bit.

BUT your proposed cone will interfere with separation (no free lunches). The cone will likely pull more debris from the side wall (than it will spare in scrubbing), unless it is at just the right height and distance from the walls.

Adding a helical baffle may actually be a better bet if you're trying to prevent bypass. The helical baffle improves the likelihood of rotation (of debris along the wall). I'm including a pic of a unit w/ a helical baffle on the inlet. The source of my image is: http://www.dustexas.com/cyclone-collectors.html

Good luck!

[Carl Weber]

Phil, Thank you for the reply. I will have to rethink my cyclone now that it is apart on my bench.

[Michael W. Clark]

I agree with Phil in that I would not recommend that modification to your outlet pipe.

At the outlet pipe, you actually want a strong vortex. This is the clean gas vortex and the stronger and tighter this vortex, separation is improved (up to a point). The vortex breakers you see on industrial cyclones are an expansion chamber below the cone of the cyclone. This chamber allows the dust to separate from the dirty gas vortex and minimize re-entrainment. It also reduces the reach of the vortex somewhat below and would allow you to fill a container higher without re-entrainment. The penalty paid is that the cyclone gets taller.

If you are getting short-circuiting, it is likely becaue your outlet pipe is too short or the inlet is too close to the outlet pipe. While you have your cyclone apart, make sure there are no ridges, bumps, or dents, especially on the curved surfaces. These can reduce the efficiency too.

Mike

[Brian W Smith]

Thanks to all for above illustrations.The last cyclone we built had the helical style ramp.It's pretty easy build as the helical centers,and supports* the down tube.It's pretty much what Phil's illustration is to a tee(ha).

*Support here comes from the fact that we're squeezing a little wider pce of metal(the actual ramp) than it would physically measure.It's a one-way fit.Like those little caps that go on a kids wagon axle.If the ramps width is sized "just right".......uuhhh,it ain't comin out,haha.So it has to be done right the first time.Best of luck,BW

[Alan Schwabacher]

Cyclones can be pretty tall. If they are too short, the vortex can reach down into the bin and pull stuff back out. Phil's baffle allows much shorter cyclones to be effective than is reasonable without it. If your cyclone would be helped, the place to put the baffle would be in the drum just below the inlet. That might not help if the vortex doesn't reach, but would not likely hurt even if it didn't help.

The helical inlet ramp is a good idea.

[Carl Weber]

All, Thank you for the input. Looks like it is back to the drawing board. I have a new Planer coming and will need to get this up and running. So looks like a helical inlet ramp is in my future.

[Carl Weber]

Thank you all for the input. I will be putting some cash away for the Clear Vue DC. What I have now would all have to be started over from scratch. As I am adding larger tools to my shop I need a larger dust collector.