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There are several types of "Dust Collection" for a workshop.  Ranging from a simple shop vacuum to fancy (and large) dust collectors.  The two basic motor types are shop vacs which suck a small volume of air very fast, and dust collectors that move a large volume of air relatively slow.  (Imagine a hair-dryer on high vs a large box fan on low.)

I will be using a shop vacuum, but even a large shop vac container will fill up fast (even for a light hobby user) and the filters will clog quickly requiring very frequent cleaning and the suction will drop a lot as the filter clogs up.  For this reason, a system to separate as much dust and debris out of the air before it reaches the shop vac filters can be a real benefit.  So I headed to the internet to do a lot of serious research on what would be the best separation method.

Sadly after weeks of research, I could not find a true comparison between the available types of separation specifically when using a shop vac instead of a dust collector.  And what was worse, it seemed that most wood/hobby shop owners have made or bought one type of separator and just stopped there, leaving no information out there that could point someone in the right direction of what would work best.

The attitude ranged from "it works, so why bother trying something else" to "I don't have a scientific lab, so I can't test it".  Neither answer satisfied me so I set to work gathering separation methods and testing them.

It is generally agreed that any decent separator will remove large particles.  It is also agreed that no separator will remove the finest invisible particles.  So I am focusing on the fine, barely visible particles.  But how to test this without scientific lab equipment?

  

  

Each test got 1 cup of sawdust from my table-saw that included fine and larger particles, then 1tsp Paprika, Ground Cloves, Ground Nutmeg, and 2tsp fine fluffy Sage.

After each test, the pipes, collection device, and shop vac container were blown out fully to provide a clean environment for the next test.  Is it a perfect scientific lab-quality test?  Of course not, but did it give me clearly visible results?  Yes.

Of course, later my dad says "Why didn't you just use colored chalk from your chalk line?"  

Well....... ummmmm.... because then my shop vac would not smell so delicious?

In any case, it worked, and yes... my shop vac does smell delicious.

I created a video that shows each method tested and some commentary on the seperation, though it may be a bit tedious to watch fully through despite clipping it as short as possible.

Here are the results if you are not up for watching the whole video...

Some notes about the Thein Baffle:  After the first two attempts at a simple Thein Baffle (so named for the guy who came up with it), I moved on with the full intention of coming back to create more versions and make more adjustments.  I fully believe that, if done right, the Thein could have full 100% separation on the spice test.  However, after creating my Semi-Thein-Clone, which acts partly like a Thein baffle by using slots to drop the debris away from the turbulent air, and partly like a true cyclone in spinning the debris for a longer distance before dropping into the lower container, I decided that I could not beat 100% visible separation and the incredible ease of making it.  (Even I have to admit that something so simple and without the ability to test past 100% makes continuing with more versions on the Thein baffles less than productive with my time.)

So, there you have it.  The Dust Deputy at $55 (plus gasket, bolts, and fittings) and my Semi-Thein-Clone at $10 (total cost), both removed 100% of the visible fine-powder particles.  But there is one more issue that could push one ahead of the other.  Comparative suction loss.

While some head-scratching and a restless night resulted, I was pretty quickly able to come up with a test to compare the suction loss.  Again, I am sure a true scientific lab could get more exacting results, but all I am looking for is a visible comparison.

To build the test was pretty simple.  Starting with a length of hose tied to a rock in a bucket of water.  The other end attached to a water bottle with a few holes in it... because we don't want to block 100% of air and accidentally suck the water all the way up the hose and into the system. Then attach the water bottle to the long vacuum hose, and ta-da!  A measurable test of the comparative suction.

  

  

This video shows the test in action:

I was pleased to find that my number and size of holes in the water bottle were right on the first try.  I started the vac with the vent on the flexible hose fully open, then slowly closed it and watched as the water was drawn up the pipe about 3/4 of the way.  (if you are replicating this test, you may have to drill more holes or less to get the water to rise to a nice level without getting drawn fully into the system)

My first test was without any collector or filter to get a base-line for the shop vac itself.  Then I added the standard filter (which showed virtually no change).

 

Then I added the hepa material filter and was able to see a noticeable drop in suction just from that.

 

My Semi-Thein-Clone was next.

 

Then the Dust Deputy.

 

However, I realized after the Dust Deputy test, that I had taped and sealed the device better than I had done with my Semi-Thein-Clone.  So I went back and re-tested with as perfect of a seal job as I could.

 

This gave some very surprising results with my Semi-Thein-Clone jumping well ahead of the Dust Deputy.  I couldn't believe that my own design was performing better than a manufacture-built device, so I went back and tried the Dust Deputy again with as perfect of a seal job as I could get.

 

The Dust Deputy did increase performance with better seals, but still did not beat or even break even with my Semi-Thein-Clone.  Definitely not what I was expecting.

In the end, with both the Dust Deputy and my Semi-Thein-Clone removing 100% of the visible fine powders, and if money were no issue, a Dust Deputy would be the easier rout to go.  However, with just a little work, the improved suction of the Semi-Thein-Clone may make it worth creating.  And let's face it, unless you buy the much more expensive Dust Deputy kit or full system, you are already going to be needing to do as much work to create your collection system as you would be doing with the Semi-Thein-Clone.