furnace blower as a dust collector

[Bill Mail]

I have a furnace blower motor, housing and squirrel cage that I was given. I was wondering if it could be used in a dust collection application. When you turn the unit on, at its highest speed, it certainly puts out a lot of air.
I would build a wooden box (see my very crude drawing) to house the unit with several 4" holes in the side of the box, facing the squirrel cage opening, to accommodate the dust collection hoses coming from a large separator can. Then more hoses to my table saw, miter saw and router table that would go to the separator can. The exhaust side of the box would be connected to a large 1 micron filter bag.
Would this give me any suction or am I just wasting my time.

[Pat O'malley]

Bill, just my opinion but I think that would be better suited for an air scrubber/cleaner.

[Michael Weber]

As Pat said it's not going to work as a dust collector. You need special blowers designed for the operating conditions in dust collection. It would make an effective dust filtration system, using filters. Lots of shop built plans for same here and elsewhere on the net.

[Pete Shermet]

Another application that this unit may be well suited for is in a downdraft sanding table, I intend to build one incorporated into an outfeed table for my saw .
Best Regards
Pete

[Rob Cunningham]

I built a down draft table with a furnace blower and it works very well. Don't think it would be good as a dust/chip collector hooked up to a machine.

[Bill Mail]

Yea I kinda thought that it wouldn't have the necessary suction power needed. My second plan was to use it as a air scrubber and have plans from Woodsmith and Shopnotes.
Off to Home Depot for filters.
Thanks to all.
BM

[Bill Mail]

By the way...is there a way that I can determine the CFM of the furnace blower unit that my HVAC guy gave me? I want to see if it will move enough air to be an effective air scrubber or not.
It is a GE Model 5kcp39kg...1/2 hp with 1050 rpm and 5.8amps.
Thanks,
BM

[Pete Shermet]

A few postee's on another forum have built the scrubbers with squirel cage bowers with integral motors and some have been multi speed, they have had to run them in the slowest speed (not sure why , noise maybe ) and they are very effective, if I had a multi speed motor I'd build that feature into it as well (Delta does!)
Best Regards
Pete

[Todd Burch]

Another issue with using those types of squirrel cages is that dust inevitably adheres to the fins, and it can become less effective and out of balance. It was designed to move filtered air.

I have one in the shop used to cool it off in the hot days of summer. I built a box around it, installed a big lazy susan swivel on the top, and hang it from the ceiling. I am able to redirect the air. Works great. It's just big.

Since my shop is a large garage and for the most part unfinished, I get a lot of heat coming down out of the attic. I'll probably remount the blower to move cooler air up into the attic to displace the hotter air.

[Prashun Patel]

I built the Shopnotes air cleaner with a squirrel cage blower. Boy, do I wish I had a furnace blower. It's PERFECT. The SN plans include 2 pre-filters and one (debatable) post filter.

The trick is finding a place to mount it.

[Bill Mail]

Yea I kinda agree about the post filter, although, I think it might be more for diffusing the air, rather than having a strong blast exiting the box.I plan to use a cheap on the post filter.
Any ideas how to determine the cfm of my furnace unit?

[Todd Burch]

It's not marked?

[Bill Mail]

If you mean is the cfm info on the motor info plate...nope?
Besides, even if it was, wouldn't that just be for the motor itself, not what would be expected when coupled to a squirrel cage inside the blower housing?

[Todd Burch]

It's a complex formula and I don't know it. There is the diameter of cage, the width of the cage, the # of fins, the angle of the fins, the speed of the cage, and probably other factors.