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can you use a simple box fan and filter to make a downdraft table?


I do art gourds and some woodworking, both of which make lots of fine dust. I have seen small downdraft table with about a 10" fan with a screen over it, but they want $175 and I just can't see paying that.
 If I cut a hole in a table and mount the fan underneath, but put a filter on top so the dust will stay out of the motor, wouldn't it do the same thing or would it not have enough power?

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I have had great success with a downdraft table constructed from two box fans and furnace filters. The key to creating suction with the fans is to remove them from the box and create a round housing around the fan blades. The problem with the box fan is that after resistance is created by the filter air just comes in from the front through the corners of the box. This is a great cheap fix... especially if you use old/junk box fans. I looked into purchasing a blower fan, but decided the cost would be better spent on a nice dust collection system that I could connect to a downdraft table. For now i'll use my downdraft table that cost about $10 for a quarter sheet of mdf. My table is 2' x 4' and uses two 20'' box fan assemblies. You could use a 20'' fan to make a 2' x 2' table, but using any smaller configuration wouldn't be worth your time... just some thoughts.
seandogue6 years ago
Look for an old vacuum cleaner. The mechanism can be scavenged to use for the purpose in a pinch. Nearly new shop, Purple Hearts, Salvation army... all come to mind...

In fact, forget scavenging, just attach the hose to your homebrew table.
I'd recommend a good-sized shop vac at least. Remember that the suction is going to be distributed across all the holes on the surface, which means you need to start with a lot to wind up with enough to be useful.

Example: http://www.rockler.com/product.cfm?page=21488
Box fans are designed to move volumes of air, but to draw it with very little restriction in the inlet, you really need a snail blower style - a bit like Rick's link but smaller.
rickharris6 years ago
You might be better off with a cyclone and good wide bore suction for dust extraction (still wear a good mask though.
dust.jpg
+1. Cyclonic filter is best if you want the fan to survive, but the principle is sound - downdraft = less airborne dust.