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Dust cyclone conundrum

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Forum topic by HD_woodchuck posted 03-09-2016 02:17 PM 877 views 0 times favorited 18 replies Add to Favorites Watch
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HD_woodchuck

39 posts in 2755 days


03-09-2016 02:17 PM

Topic tags/keywords: cyclone dust collection dust shopvac

Hey guys, before I even get started I’ll apologize as I know there are over 10 pages of forum articles/threads on various cyclone collection issues, etc. and I’ve read over most of them, however I still have a question …

I recently purchased a Dust Deputy (the small plastic version) for my micro shop. I only run one tool at a time, and believe it to be sufficient for what I need. I have it hooked up to a 5hp/145CFM ShopVac. ShopVac seems to have plenty of draw for what I need and certainly improves the dust in my shop.

The cyclone is mounted on top of a 45gal fiber drum which also has a fiber lid secured with a metal locking band. Inside the drum I have a heavy duty clear plastic garbage bag. This made complete sense to me so that I could simply tie the bag closed and pull it out when full, and replace with a new one.

Everything worked great until my second bag. I noticed immediately that the plastic bag inside was just getting sucked up into the bottom of the cyclone, and I was back to emptying the ShopVac every few minutes (when using my planer it fills up quick!).

I’ve reviewed many articles online and in this forum, and see that some people have made a metal “rack” to fit inside the bag/can, but have to remove it before removing the full bags. One guy here made a plastic insert out of another barrel, but again has to remove it prior to replacing the bag.

Looking for other suggestions / solutions if there are any. I’m not a welder, so paying someone to weld a custom rack fit to my drum doesn’t make a lot of sense to me.

Suggestions?


18 replies so far

View eflanders's profile

eflanders

87 posts in 1318 days


#1 posted 03-09-2016 02:50 PM

How about just cutting out a wooden circle or ring to fit the bottom of the bag. Just place it in the bag so it sits snug between the bag and your barrel bottom. It should be enough weight to hold it in place, cheap and easily made.

View Fred Hargis's profile

Fred Hargis

3951 posts in 1961 days


#2 posted 03-09-2016 03:04 PM

Besides having something that fits inside the bag (I have an insert made from a plastic drum), the only other scheme I’ve seen to handle this was maintaining negative pressure on the outside of the bag, enough to keep it in place. Oneida actually makes (or used to) a vacuum pump that you piped to the drum and it generated enough vacuum to keep the bag down. The other “version” of this is to run a second pipe from the DC inlet (Ive only seen this on DCs, never a shop vac) to the lower drum. I agree the plastic liner insert thing isn’t all the handy, but I can get to it when the bag is full to pull it out and it beats nothing.

-- Our village hasn't lost it's idiot, he was elected to congress.

View HD_woodchuck's profile

HD_woodchuck

39 posts in 2755 days


#3 posted 03-09-2016 03:15 PM

thanks eflanders, I thought about a weight but then I would need one in every bag … the bags are thrown in garbage when full and a new empty bag put in

Also thought about clipping some weights to the outside bottom of the bags … not sure how well that will work

FH, guess I may have to follow your footsteps with an insert

View eflanders's profile

eflanders

87 posts in 1318 days


#4 posted 03-09-2016 03:25 PM

Ok, so you dispose of the bags. How about using a piece of double sided tape on the bottom of your container? Otherwise some sort of bag retention clip as mentioned… I have some magnetic clips that hang on my refrigerator for pictures etc. Maybe you could glue on a rare earth magnet to a clothes pin? The magnet would stick to a metal collection barrel, then clip onto the bag bottom. Of course then you would have to add a metallic piece to the bottom of your fiber barrel…

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HD_woodchuck

39 posts in 2755 days


#5 posted 03-09-2016 03:49 PM

thanks eflanders, again all good suggestions.

Think I’ll put some energy into making a wire insert which doesn’t require welding, light enough to pull out when bags are full (without making a mess), and cheap enough to make from common materials.

thinking maybe old wire clothes hangers???

View WhyMe's profile

WhyMe

618 posts in 1029 days


#6 posted 03-09-2016 03:52 PM

If the first bag worked and the second didn’t tells me you have a small leak that is letting air in around the outside of the bag. If the container is sealed completely the bag should not get sucked up into the cyclone.

View HD_woodchuck's profile

HD_woodchuck

39 posts in 2755 days


#7 posted 03-09-2016 04:09 PM

whyme … interesting thought. As soon as I noticed the issue on the second bag, I did duck tape the bottom of the barrel as it wasn’t completely sealed (being a fiber barrel used for industrial weld wire, there is no need for it to be completely sealed). I also checked for any other leaks.

Tonight I will change out the bag (since its full as I’ve been emptying the shop vac into it to see if the weight of more sawdust would hold it down). Maybe now with the leaks sealed, the third bag may work better

View WhyMe's profile

WhyMe

618 posts in 1029 days


#8 posted 03-09-2016 04:24 PM

The barrel does need to be airtight because leakage reduces the effectiveness of the cyclone separator. A very very small leak may not produce any noticeable difference in the cyclone performance. The small leak is enough though to cause the pressure to be higher on the outside of the bag causing the bag to be sucked up to the cyclone.

View BobAnderton's profile

BobAnderton

219 posts in 2258 days


#9 posted 03-09-2016 04:26 PM

I’m thinking make a wooden ring the size of the top of your drum and set into it a series of dowels that point down from the ring and extend to the bottom of the drum. The cyclone will dump dust in through the hole in the middle of the ring and when you remove the drum lid the ring will be sitting there on top. The dowels will keep the bag in place in the drum and it will be easy to pull out.

-- Bob Anderton - Austin, TX - Nova 3000 lathe, Alaskan Mark III mill, Husqavarna Saw

View WhyMe's profile

WhyMe

618 posts in 1029 days


#10 posted 03-09-2016 06:38 PM

Another solution is not to pull the top of the bag over the lip of the drum and sealing it with the lid, but to make a inner bag holder kind of like BobAnderton suggested with the entire bag being inside the drum. That way the vacuum pressure is equal on both the inside and outside of the bag which should prevent the bag from being sucked up to the cyclone.

View HD_woodchuck's profile

HD_woodchuck

39 posts in 2755 days


#11 posted 03-09-2016 07:17 PM

ahhh … another great suggestion!

Ok, lots to play with later

thanks all

View ShemATC's profile

ShemATC

1 post in 276 days


#12 posted 03-09-2016 09:57 PM

Don’t over think the problem. The issue is only when the bag is brand new and empty. You said you don’t want to waste a weight in the bottom every time you empty the bag, but what about a simple piece of scrap wood? I’m guessing in the time it takes to create enough dust to fill a bag you’ll have created a decent amount of scrap. Put just enough pieces in the bottom of the bag to weight it down (even with a shop vac I’m guessing a piece or two would be the most needed). It’s scrap so you were going to throw it anyway so no loss. Avoid sharp pieces of ply to ensure the bag doesn’t rip.

View pintodeluxe's profile

pintodeluxe

4859 posts in 2281 days


#13 posted 03-09-2016 10:12 PM

Here is one solution (not my photo)

You’ll need to fabricate or source a cage that can support the bag. Take a look at the larger 2-3hp portable cyclones and how they solve the problem. This might give you some good ideas to solve your dilemma.

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

View shipwright's profile

shipwright

7175 posts in 2266 days


#14 posted 03-09-2016 10:23 PM

I just empty my unlined drum (steel garbage can) into another trash can that has a bag in it and then tie it up and discard it. It’s not hard and doesn’t have to be a dusty job. I find it the easiest way to go.

-- Paul M ..............If God wanted us to have fiberglass boats he would have given us fibreglass trees. http://thecanadianschooloffrenchmarquetry.com/

View JayMnKato's profile

JayMnKato

8 posts in 646 days


#15 posted 03-09-2016 10:53 PM

How about a couple rare earth magnets epoxied to the inside bottom of the drum then when you put a new bag in set in some metal fender washers or random hardware on top of the magnet to sandwich the bag between the washer and the magnet and hold it in place?

Yeah, you would lose the washers when you throw the bag away but the loss wouldn’t be that great and may be worth it. The bag may need to be pretty strong though, so that they don’t just pull through when you lift the bag.

-- --Jay

showing 1 through 15 of 18 replies

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