Why this shroud on DC fan inlet?

[Mark Burnette]

What purpose does this shroud serve...and does it need to be this large?
http://i170.photobucket.com/albums/u273/guy48065/Shop/DCshroud.jpg

My 2nd-hand DC works well enough but the previous owner added this sheetmetal shroud. I assume it's so the chips don't fly from the intake elbow right into the impeller (which doesn't seem all that likely). It hangs way down into the drum so capacity is only about 1/2 what it could be.

OTOH I never need to shake out the bag...until I forget to check the drum level.

[Steven Satur]

My old Delta was like that. Kind of a half a##ed attempt of a cyclone I think. The dust and chips will come into the barrel and swirl around to the bottom, only problem is the dust would go right to the bag.

Steve

[Julie Moriarty]

My old Delta was like that. Kind of a half a##ed attempt of a cyclone I think. The dust and chips will come into the barrel and swirl around to the bottom, only problem is the dust would go right to the bag.

Steve

My Delta didn't have that "option" but it certainly sucked up everything and left little in the drum. I recently built a cyclone attachment for it and it works like a charm, except now I actually have to empty the drum.

[Phil Thien]

The idea was to get some cyclonic motion in the drum.

It didn't work. Most of those just eventually spit everything into the bag.

Some people have modified their two stage units (like you have there) with one of my baffles. That combination works pretty well, if I do have to say so myself.

[Mark Burnette]

I truly never need to empty the bag but I don't know if this huge shroud is the key or if this DC was designed correctly from the start.

Looks like I will need to do some testing with & without the shroud. I guess I can suck up a big pile of dust a few times and weigh the bag.

Phil I'm familiar with your baffle but I don't recall seeing a 2-stage version. How is that built? An even larger (but hopefully shallow) shroud with the baffle in the bottom?

[Mark Burnette]

My unit originally came out of a factory and had been on a graphite process. As nasty & dirty as graphite is I'm betting some extra effort went into keeping the fine stuff out of the bag.

[johnny means]

Without a shroud like that in place the air and chips travel straight from the inlet to the fan. the shroud forces chips to move towards the dead air space, where they can settle.

[Lee Schierer]

The idea was to get some cyclonic motion in the drum.

It didn't work. Most of those just eventually spit everything into the bag.

Some people have modified their two stage units (like you have there) with one of my baffles. That combination works pretty well, if I do have to say so myself.

I modified my Delta DC with Phil's baffle and the 55 gal drum now fills up about 2/3 full and I get less dust and debris in the filter bag with no apparent loss of suction.

[Julie Moriarty]

If you ever think about adding a cyclone, this is what I did with mine:

http://i867.photobucket.com/albums/ab233/jules42651/dc/dc_after.jpg

It works so much better than before. And all the fine dust vents to the outside. There is no bag and no concerns about fine dust re-entering the shop. I used a standard 4" dryer vent to vent outside.

Before the cyclone there was so much dust and chips thrown outside I had to regularly rake it up off the grass. But I rarely bothered to empty the drum canister because there was almost nothing in it.

I've had this set up for a few months and I can't find a trace of dust outside but I now have to empty the canister regularly.

[Paul Incognito]

Julie,
Nice loking cyclone! Can you give me some specifics on it? Did you build it yourself? What's the motor hp? Impeller size?
I've been thinking about wether it's worth it to buy a cyclone off ebay and modify my Grizzly 2 hp unit or to buy a whole new machine.
Thanks,
Paul