Using blower fans to make DIY dust extraction - advice?

[trumpetmonkey]

I have two biggish propane blower heaters, not working but the fans still work. I really need to deal with dust in the workshop, I only have a little vac at the moment. Thinking of making my own dust extractor and/or air cleaning filter, since I have these things lying around, and no money.

Any tips?

Would it be such a bad idea to just suck dust and chips straight through the fan, keeping it in existing metal tube, attaching duct to inlet and big bag to outlet??

 

[Woodwizard]

Mmmm.... makes me nervous, but I've seen crazier things work!

You main problem might be the difference between:

a) the action of moving air - usually done with a fan, as will be found in the heaters.

b) creating suction, like a dust extractor / Hoover. Usually accomplished with an impeller, as found in extractors.

Fans are good at moving air, but no good at creating suction. Look at a hair dryer. Moves lots of air, but put your hand over back and the suction disappears with the air flow.

 

[wallace]

I wanted to make a decent extractor near my lathe on the cheap, so I went to my local scrapyard and got a car cooling fan stuck it in place of a window and had a 12 volt supply. works really well at removeing the small stuff from the workshop. Also to prevent the hole shop getting covered in fine dust I suspended a desk fan upside down from the ceiling pointing in the direction of the lathe. This blows all the dust towards the extractor fan and then gets sucked out. great in the summer not so great in the winter.

 

[trumpetmonkey]

Woodwizard that is enlightening I never knew that difference. And I still haven't got my head round how workshop chip collectors work - how are dust and chips sucked into a bag at the bottom without going through the motor itself - or is that what does happen?

So Wallace maybe these fans would be best used as fine dust extractors, or air filtration if I attach some filter material to the front.

 

[Woodwizard]

Before someone corrects me, i think a fan is 'technically' an impeller, but you got the jist of what i was saying.

As for how extractors work - yes, the chips and dust do seem to pass through the impeller itself.

The horrendous noise my extractor makes whenever a discarded latex glove goes through it seems to confirm this!!

 

[trumpetmonkey]

While we're at it, what brands and models of workshop extractors can people recommend? I ought to buy a proper on one day! Need to go nearer the cheaper end.