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Ultimate Mobile Woodworking Bench (UMWB) #7: Testing the dust separator

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Blog entry by Garry posted 233 days ago 2481 reads 0 times favorited 1 comment Add to Favorites Watch
« Part 6: Electric power Part 7 of Ultimate Mobile Woodworking Bench (UMWB) series Part 8: Final details for the UMWW »

I posted two projects related to the dust collection system designed into this mobile workbench. Click the links for the compact Thien dust separator and the rotary blast gates.

The dust separator seemed extremely effective with almost no carryover to the vacuum. I was anxious test and document how effective, so I followed the example of some LJers and set up a test. I measured the contents of the dust separator bin and dumped it on the floor. I also swept up the shop floor which included a collection of leaves blown in when the garage door was open. I had to remove the leaves manually since they blocked the suction nozzle.

The contents of the bin = ~3.5×15 x 15 = 787.5 cubic inches
The amount of dust in the vacuum after the test = ~5.5 cups = 79 cubic inches
Dust separator effectiveness for this test = 90%

Here are some before and after photos and video of the separator cyclone in action.

Volume of sawdust (~790 cubic inches)

Volume of fine dust in vacuum after the test:

Measuring the dust after shaking out the filter (~79 cubic inches):

Here’s a brief video of the cyclone separator in action:
http://www.youtube.com/watch?v=T_jHfquMDV0

And here’s a brief video of the dust/air flow in the air manifold.
http://www.youtube.com/watch?v=3WjipnAvZpo

What I learned:
  • 90% is good but I was actually disappointed that the results weren’t even better. I had previously seen almost no perceptible carryover. Perhaps the heavy loading affected the efficiency. I cleaned out the vacuum and will monitor the results over a long term with normal loading.
  • The heavy loading also seemed to cause dust to build up in the air manifold although it didn’t seem to block flow. I’ve added a curved baffle which I hope will keep the dust moving. More later.

-- Garry, North Carolina woodworker and engineer - The journey you're preparing for has already begun.



1 comment so far

View Gianni's profile

Gianni

122 posts in 599 days


#1 posted 233 days ago

Interesting result. When I first pieced mine together, I left the parts loose so I could experiment. One thing that made a big difference was raising the “suck” pipe (mine is upside down from yours) higher such that there was more space between the end of the pipe and the face of the opposing plate. It seemed counterintuitive that a wider gap there spun out more dust, but I think maybe the gap was originally too close to the area of the pipe cross section and was limiting the “spin” in favor of an omnidirectional vertical suck, if that makes sense.

In it’s current form, the outlet is only about 1 to 1 1/2 inches into a chamber that is around 5” high, and pretty much everything but sanding dust is near-totally spun out (planer and jointer shavings, table saw and router chips, drill press shavings, etc). Have done some bandsaw and scrollsaw dust, but not in any kind of controlled test like you have done. I should do that and see how it goes.

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