Shop made dust filtration unit

[joe Katzenberger]

I am about to start on a shop built dust filtration unit using a pre-filter and then a "bag unit" as used in the factory units. My thought was to use an attic fan, bought from a Borg, on the output side. Looking at the fan motor assembly I am concerned about the openings in the motor shroud and the possibilty of an explosion. Am I being engineer parnoid? Has anyone walked down the same path with success? I have looked around for a cast off heating system squirrel cage blower but have zip success. Should I hold off until I can find one?
Thanks ya'all, joe Katzenberger

[Lucas Moore]

Been thinking about doing the exact same thing. Seems like you could make a nice custom unit for a fraction of the price of a retail version. As for the explosion proof part, are you using combustible agents in concentrations that worry you, or are concerned about fine dust accumulation in the interior housing? I do believe that a squirrel cage would be more quite than an attic fan but I'm not for sure on that.

Let me know how it goes and post some pics of progress.

[David Hostetler]

Unless you are spraying volatile finishes in there, I am not sure you have anything to worry about if all you are worrying about is the dust... Better safe than sorry though right? For what it's worth, your right on the really ought to wait until you can source up a proper squirrel cage blower. I am actually surprised you haven't been able to come up with one. If nothing else, check Craigslist... There are contractors here selling pull outs for $50.00

[John McClanahan]

From what I understand, a squirrel cage blower can create more pressure than an axial blade fan. You will need the extra force to move the air through several fine filters.

An air filter is on my list of things to build, if my shop ever thaws out!

John

[JohnT Fitzgerald]

From what I understand, a squirrel cage blower can create more pressure than an axial blade fan. You will need the extra force to move the air through several fine filters.


Agreed - an attic fan would not be able to push enough air through the restrictions of a DC system. Hit up the HVAC contractors in your area for a blower from an old AC or heating system. You might also look into any recycling centers in your area - our town runs one where people dump off a lot of old stuff, and sometimes you can score a good blower that still works.

[Robert Malone]

Hey Joe! You have too many Heating/Air companies in your area. Call a couple
of them and talk to an install Foreman (if that's what they're called).
Tell them what you're looking for and make a deal.
Build your box around it. Most likely a 12"X24" cause of filters and size.
I just threw away a 220V rat cage because I could only get 1 of 3 speeds to work.
So, I'm looking again to start my filter.

[Bill Blackburn]

Simple squirrel cage from a furnace, some filters from a BORG to the outside and if you really want to get fancy add a 0.5mic felt bag (Graingers or others have) to the inside.
You can make to thing to whatever size you desire to accomodate number of filters you want to use of course so the size will vary.
Mine is a 110v motor - it's wired for multi speeds but I use it only on the lowest anyway - it is a powerful devil.

I suspect if you make a call or 2 to some HVAC shops you'll be offered one for free or very cheap. They seldom go bad.

If I can remember to I will post pics when I find my camera. Seems it ran off like so many things seem to be doing lately here. The kids are all in town - things go away fast:(

[Dave Beauchesne]

Greetings:

Besides having an advantage in the fact I am a HVAC guy, I figured I could do this as a project.

A prop fan will not work for this application - as you increase the pressure drop over a prop fan, the amperage increases and you will overheat it and possibly cause a fire. A squirrel cage blower is the proper fan to use. The amperage actually drops off ( to a point ) as you restrict air flow; so a plugged up filter does not harm the fan ( again, to a point ). Try to get a direct drive squirrel cage blower with a direct drive fan motor; something from a trailer furnace is great, as they don't have huge capacity and you don't have to worry about a belt. Almost all new furnaces are direct drive, but many are designed to move 1200 CFM or higher - it will cause a vortex in the shop.

Make sure you have at least two stages of filtration - I have a 2 inch pleated, MERV 14 ( higher MERV = better particulate capture ) as well as a 2 inch pre-filter that I apply air filter oil to - - this allows smaller particles to stick to the filter fibers and catch more junk before it gets to the main filter.

Now, since I am a HVAC guy, I took the remote control out of a scrapped window A/C, mounted the controls in a proper electrical box, and viola, I have a fully remote controlled, 3 speed, air filter WITH a timer that was a function of the old window unit - I turn it on and can set it for XX number of hours. Be sure to ground everything properly.

I was also able to scrounge a metal case from a cased ' A ' coil, to me a bit safer than wood as it can be fully grounded, with the added bonus of having acoustic insulation inside it, which deadens the noise a bit.

I hung it by chains near the ceiling in my 10 foot high shop; works like a dream.:D

Just my 2 cents -

Dave Beauchesne

[Joe A Faulkner]

You might want to check out this project where a guy built a down draft sanding table, using a furnace blower, that doubles as an outfeed table for his table saw and an air cleaner.
http://www.woodworkersworkshop.com/plansshare/air_filter_downdraft_sanding_table.htm

[Joe Wiliams]

What CFM rating should we look for?

[Keith Westfall]

My neighbour was having their furnace replaced and the "installer" said I could have what I wanted! I grabbed the blower assembly and then built the following.

Double filters on two sides, and so far no dust on the motor, so I don't think much is going through...

It's quiet, and it moves the air! Discharge out the bottom helps move the dust off the floor!!

Switch added for unit and extra plugs in the back for the 2 sanders and other things.

Wheels make it mobile and overall I am happy with it!

[Tom Clark FL]

Mine is around 20 years old and still works great. It uses a cage to suck dust in the front by my workbench, where I am always routing and sanding. Exhaust is in the back. The filter is a four-inch thick pleated one, and it keeps the shop air clear. By the way, there is very little dust inside. The drawers also come in handy to hold tools.

[joe Katzenberger]

Thanks to all for the ideas and suggestions. I have been calling around to the HVAC shops but the junk man seems to be very active in picking up used blowers and motors quickly! Several companies on the web offer the Dayton brand, brand new, and a lot less than Grainger advertises. I might go that route if I can not find a good used unit.
I will keep you posted if I come across any great and inexpensive solutions.
Thanks, joe K

[Robert Malone]

Hang in there a little longer Joe!
Your post got me off my butt looking for a pair.

[Neil Brooks]

Just my 2 cents -

Dave Beauchesne

My gut tells me ... there's a market for these ... if somebody like you were interested.

I finally bought a used, high CFM JDS model, but ... ???