# 3 stage 3 speed workshop air filter WIP



## Chrisp (19 Jun 2012)

Originally posted in the woodturning section but might be of interest to others  
To work along side my dust extractor and to filter all the time I'm in the workshop, I have made this 3 stage, 3 speed air filter, 32" long 16" wide and 15" tall. Using scrap MDF, an old cooker hood extraction unit, some polyester wadding as a pre filter, large car air filter as big as I could purchase, pollen internal filter and some silicone. 


 
The MDF components and filters. 


 
The box assembled. 



The internal filter is a car pollen filter, all silicon sealed in place to make sure it is air tight and maximise air flow. 


 
The cooker hood fan fitted to the rear plate, switch is fixed in place so its easily operated. 


 
Rear view showing the outlet and switch placement. 


 
Front view showing polyester pre filter and metal fittings used to hang it from the ceiling. 


 
After some grinding and with the filter on 2nd speed, a quick vacuum around the outside shows how it is performing. 
I used materials that I had in my workshop and a motor donated from a friend, overall cost about £25 and a much more comfortable working environment. 
Regards Chris.


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## Allylearm (30 Sep 2012)

Good idea for a problem much overlooked in workshops and at that price well within everyones scope.


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## psm (3 Feb 2013)

i tend to breath more in than the extactor


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## jaywhoopee (6 Feb 2013)

In case anyone is inspired to do similar, I have a cooker hood (new, unused but dented in transit) which I'd be glad to donate 

(Now taken 19/2/2013)


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## Orion801 (29 Mar 2013)

I've been inspired by this to carry out a very similar project. I'm got myself a pre-filter from Axminster for £8 which is a spare part for one of their own air filter models as well as a large car air filter and cabin pollen filter from Halfords (which cost £11 for the both of them after I managed to persuade them I deserved a trade card ). I also have an old cooker hood which has proven to be one of the most horrendously greasy things to clean I've ever come across (and I'm used to working on 15 year old motorbikes!).

Anyway, here's a few screenshots of the design I'm intending on going for:

Overall view:




OverallView by Orion801, on Flickr

Front panel removed:




SideRemoved by Orion801, on Flickr

I plan on fixing everything together with dowels and screws, without any glue, so that it can be easily disassembled if I need to replace any filters at any stage. I then intend to use silicone sealant as in ChrisP's design to prevent any air leaking past the filters (I know this will make disassembly tricky but at least I'll only need to remove sealant which will all be visible which will be much easier than if everything was glued).

All of the sealed assembly will be done with the front panel removed. I intend to apply some foam draft excluders to the inside surface of this to seal against the panels holding the filters in place rather than using silicone sealant. This will allow me to easily remove the panel as needed so that I can clean the filters (I've tried to leave enough space in between each to fit a hoover attachment). Once the front panel is in place I'm going to use duct tape around the remaining unsealed edges to the rest of the assembly which again should be easy to remove.

Another tweak to the original design I'm planning on implementing is adding some chicken wire over the exhaust duct from the fan to prevent anything large dropping into it (as it will be facing upwards) as well as on either side of the pre-filter to prevent it from being damaged during cleaning.


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