Baffle vers. wok?

[Jeeper]

I got into all the hype and added a wok to my DC nd piped the exhaust to a vent in my shop's wall.

The second day I was running my sander (16 32) and my gf asked me why there was smoke coming out of hte vent on the garage.

I got scare and shut everything off but could not find any fire.  I turned it back on and went out and looked what looked like smoke coming out.  It was dust and I was not even running my sander just the collector!!

Do you tyhink I would see an improv. if I went with a Thein Baffle?

[phil (admin)]

LOL.  Woks are for cooking.

Okay, I've seen the Wok threads on various forums.  My favorite was a link to an article which stated "Much to my surprise, the filter was cleaner than when I installed it!"  Here is a link:

http://www.popularwoodworking.com/tools/shop-made-vortex-dust-collector-woks-on

Claims like that result in me being fairly skeptical about the rest of the piece.

First, let me state that the bowl and cone shapes are some of the first shapes I experimented with.  It is only natural, as we're accustomed to seeing cones on cyclones.  And we know cyclones are the holy grail of separation.  Therefor, it is the logical starting point.

The various cones, bowls, and funnels (I had a huge collection of giant funnels at one point) that I tried worked okay, but they had significant shortcomings.

When the bottom bag is empty, they do a good job at keeping chips from getting to the filter (or, in your case, the exhaust pipe).  But the finest dust still sneaks through.  And as the bottom bag fills, more and more chips and fine dust are discharged to the filter/exhaust.

In trying all sorts of different shapes (including my favorite, Frisbees), I discovered that these devices had one thing in common:  They were perfectly circular.  Basically, they left a gap around the entire circumference of the separator.

And that 360-degree gap allowed the incoming air above the bowl or Frisbee or funnel to couple with the air below and spin it at great speed. 

Here, you can look at the two videos below and see the difference.  The debris in the bottom bag of the Jet unit is spinning violently, and the debris in the bottom of the unit with the Thien baffle is perfectly still.

Jet DC w/ Cone:
http://www.youtube.com/watch?v=T-KNCb7bEkc

DC with a Thien baffle:
http://www.youtube.com/watch?v=9MSOCePr35s

Why is this important?  Well, when you are scrubbing the debris in the bottom of the bag, you're lifting the finest dust and reintroducing it into circulation and increasing the chance it will blow right into your filter.

That is probably why even Jet only claims something like the Vortex Cone getting only 98% of the chips.  And they don't even mention fines.

After circular shapes, I started playing with shapes that would prevent this scrubbing.  I tried baffles with many slots (clogged).  I tried baffles with vanes (clogged).  I tried all sorts of shapes.

Ultimately, the baffle I settled on and which I've documented here was the winner.  The 120-degree smaller diameter and the somewhat small (1-1/8" slot) decouple the air masses above and below the baffle and prevent the fast moving air above the baffle from spinning the air BELOW the baffle.

Not only is scrubbing prevented, but separation is improved.  Here is why:

When the air above the baffle comes to the section of the baffle with the slot, it attempts to combine with the bottom air and spin together.  But the limited area prevents coupling and the bottom air mass spins very slowly.  And that difference is all it takes for the bottom air mass to "grab" even much of the finest dust and drop it to the bottom of the bag.

So to answer your question (if you are still reading this), yes, the baffle will outperform anything like a wok or a salad bowl.  I know, it takes some effort to cut the unit out of a 1/8" or 1/4" piece of hardboard.  Yes, you will have to use a protractor.  But there are no free lunches.  If you want the best performance you can achieve, then use the wok for your fried rice, and make a baffle for your dust collector.