dust extractors

I'm not sure what kind of dust you're tying to extract, but if it's metal dust you need at least 650CFM. Here's the route I took in 2004. Rather than retype everything and risk loosing important details, I just cut it from my original post:

In my little home shop I have one surface grinder, a couple of snag grinders, and a small belt sander that I use only for metal. (I've since added a Deckel SO grinder and a T&C grinder) The surface grinder was my primary concern so I based all of my requirements for dust collection on it. I watched industrial Torit type units on Ebay for several months hoping that I could snag one close enough to home to pick up myself and save freight. Not having a forklift to unload a semi is one drawback, then having to either buy yet another VFD or change a motor out was another.

I refined my list of requirements to fit my wants: single phase, fine filtration, mobile, quiet, safe (from fires) and CHEAP. My wants pretty much decimated the majority of dust collectors available on the net. A friend gave me an old furnace blower so I started prototyping a dust collector around it. I figured that I'd just start trying stuff. Then I pulled the covers off of a Torit #64 at work to see what they did. To make a long story short, the furnace fan wasn't feasible (but it was quiet) without using a 10" duct. I was about ready to give up when I found a damaged 650CFM HF dust collector on Ebay for $30. I wasn't going to use the broken part anyway, and it was about an hour drive each way to get it. The noise that it made measured out at 95dB sitting on the floor. Putting it in the box I had left from my furnace blower attempt dropped it to 85dB and adding the insulated exhaust stack took it down to a manageable 75dB. Since this is a prototype I figure that I'll remake it out of steel on a smaller scale to fit the HF impeller later on. (I never did) I used MDF for the current case. I know it can burn, but I often use MDF for impromptu welding jigs and seldom do I ever get a flame from stick welding directly against it. I've got around $50 in everything so far, and the suction is very strong. The 5 filter bags were picked up at a local flea market. I found them in the McMaster catalog as polyester filter bags rated at 25 gallons/min. (Still using the same filter bags 10 years later!) I think the catalog had the mesh size at around 2-3 micron. I held a piece of filter over a butane flame and it melted but would not catch fire. I added the close weave (HEPA) furnace filter on top for good measure, and the whole tray slides out for maintenance. I’m sure there’s a few things I can come up with to improve on it, from what I’ve read, I could use a lot more surface area on the filter bags. I’m open to suggestions from the group.

I was going to add a shaker bar to knock the dust off the filter bags, never got around to it.

In the pictures below the dust is pulled in through the intake hose into a narrow chamber in the lower half of the unit and is drawn down to the bottom where there is a 3" opening at the bottom of the chamber. Heavy dust falls into the steel chip pan while lighter dust is drawn up into the filter bags where anything larger than 3 microns is caught. he air and finer dust passes through the pleated HEPA filter and the cleaned air is drawn up into the impeller and exhausted through the foam lined tower tower which is taller than me in order to keep the noise overhead. At 75 decibels I can still hear the radio in the shop while I'm grinding.

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I have a Dust Deputy on my blast cabinet, and it works excellent. The hose goes from my blast cabinet, through the Dust Deputy cyclone, through the Shop Vac, and out through the back wall of the garage. I run the Shop Vac with no filter because of the Dust Deputy and the outlet going outside, so there is no loss of suction in the system.

It moves so much air that I have not had to change media in my blast cabinet. When the media is turned to dust it is drawn out by the vac, and I just add new media from time to time. My blast cabinet is pretty large, so this is a pretty impressive movement of air. I use Black Magnum from Menards as my media of choice.

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That's a Harbor Freight bench top blast cabinet inside of my cabinet with the door closed (and lots of room to spare).

GG

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In my old shop before we moved to the country I had a sears shop-vac hooked to a home made catch can for metal and sparks and it worked well enough to really have a good go at cleaning up the mess I usually ended up making. All of the little razor blades and other chips got caught in my catch can and only a very small amount of really fine stuff got through. I used the foam filter sleeve and it worked perfectly with little or no loss of suction and good clean floors and equipment. The new shop still has a really long way to go, but I will get there eventually. The pick up hose was a pool suction hose for the underwater vacuum so it would reach anywhere in the shop easily too. Sure do wish I had kept all that stuff from before. Oh well, live and learn I guess.

Bob
 
Thanks for the feedback guys. I planned to only use it for vacuuming up chips in and around my mill. This exercise started with me trying to get the chips out of the filter of a small cheapo vac I bought at Lowes years ago. Having a separate container for all of the metal chips, oil and cutting fluids is appealing.

-Joe
 
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