# The case of the collapsing drum



## careforapint

I just finished building my cyclone dust separator (based on SimonSKL's blog post and it worked flawlessly!

One problem I have with the plans was that the 5 gal. bucket was filling up too fast. I saw that some other folks have mounted theirs to a fiber drum, so I went ahead and ordered a 20 gallon one. My assembly is now completed, but if there's anything blocking the airflow, the fiber drum wants to implode. One of the attractions of this design is that instead of spending $400 on a system, I've spent about $45.

Any suggestions on how to reinforce the drum? I don't really want to have to buy another container.


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## rance

I understand you can get 55 gal plastic drums on the cheap. Like $15 from the Pepsi plant. Or medium size ones for free from car wash places. Or you could add a metal band around your fiber drum.

Where in VA are you?


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## Gene01

I use a 35 Gal galvanized trash can.


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## ajosephg

I have the same problem using a metal trash can. Some day I'm going to make a several rings (out of plywood) and insert them into the can.


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## careforapint

I was thinking about adding vertical ferring strips to the outside and then adding the metal band (@rance) suggested to add stability…but then haven't I just made a barrel? LOL

The drum is about 25" high and another issue is you don't know when it's full. I'm also considering cutting a thin vertical hole (approx 3/8" x 6") near the top of the drum where I'll epoxy in a thin clear piece of plexi to serve as a window to tell when the drum needs emptying.

@rance - Charlottesville


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## careforapint

@joe - wow, I wouldn't have thought a metal trash can would be subject to imploding. What size vacuum are you using?

I've just got mine hooked up to my 5.5Hp Ridgid shop vac. and using 2 1/2" PVC for my run. Aside from the drum collapsing, it works fantastic.


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## ajosephg

I have a Sears/Craftsman wet/dry vac. Not sure off hand what the HP is, but I think it is 5 or 6 HP.

The imploding doesn't seem to affect the function, as the lid still stays sealed. It just looks bad, and makes you jump when it happens, 'cause of the the loud pop.


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## tomd

If you don't want the size of a 55 gal. drum I use a 35 gal. plastic shipping drum they use them for shipping concetrated orange juice. I bought one at the local recycler for 8 bucks. P.S. it fits perfectly under a HF dust collector, even the original band will fit with no modification.


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## pauljp

I went thru this as well when I built my dust separator.
I bought a plastic trash can and it collapsed.
I bought a heavier "Brute Rubbermaid" trash can and the same thing happened.
I welded a metal ring that fit in the middle inside and it still imploded, just at different places.
I finally found a metal trash can (hard to find in Canada) and it works great.
No imploding even when airflow is blocked.
I use a very loud Craftsman shop-vac.


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## A10GAC

This comes from J. Phil Thien's DIY Forums…took me a while to find it, but here's a link to a DIY vacuum relief valve for dust collection systems. http://www.cgallery.com/smf/index.php?topic=198.0 Theory dictates that once the valve activates it should relieve the vacuum and prevent a collapse and allowing you to continue using the fiber drum.

Interestingly enough, the last post is from March and was posted by a DavidCGrimes. (Not sure but it could be the same David Grimes registered here on LJ's…small world, eh?) He found a ready to use commercial version that is normally used for central vac systems (link included in the thread, runs $12.99 USD)...no word on how well the commercial version worked.


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## MrRon

A drum shouldn't implode unless you shut off the inlet gate to the drum (separator). Doing so, you are sucking all the air out of the drum causing it to collapse. I did this once with a 55 gal plastic drum using just a shop vac. You should never run a DC with all gates closed.


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## wdwrkr

A10GAC's response is spot on. The solution should not be a brute force one - like reinforcing the drum. The vacuum pressure relief valve is elegant - and reliable. You could easily fashion a relief valve by attaching a spring to a "hinged gate" and have the gate open when all of the machine-attached gates are closed. Then no matter what drum you use, you will never have a failure.


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## pauljp

You know… that is an absolutely brilliant idea.
I wish I had thought of a relief valve or a simple hinged gate that would have solved my long problem with collapsing garbage cans.
I kept buying garbage cans trying to find one that would keep its shape under pressure.
For a while, I had more cans in my shop than tools.
I don't know why I have a hard time coming up with great ideas like that.
As I said… absolutely brilliant !!
I love this site.


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## FirehouseWoodworking

I have a built a cylcone separator. I don't use a drum. I built a plywood box from 3/4" AC plywood. The top is square instead of the round one required of a drum.

All the seams are glued, screwed, and then caulked on the inside with silicone caulk.

I suppose that if you use a Thein separator, you could build a segmented barrel out of plywood. A couple strap clamps would hold the staves together while the glue dries.

Works great. Just a thought.

Cheers!


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## careforapint

Well, I tried a few experiments (all failed) and now I think I'm going to try the relief valve. As soon as I get it put together, I'll post my progress.


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## HobbyBOB

vacuum pressure relief valve

Old post I just found. It gave me some basic ideas for creating a relief valve.

Here the solution I made after Isuffered an imploding garbage can.


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## woodbutcherbynight

A PCV valve from a car would do same thing. The vacuum hose side would need to be facing inside the can / drum with the vent facing outside. When vacuum is applied the spring would be pulled down and vent off a small proportioned amount. A PT Cruiser has a screw on PCV just install upside down from inside the can. Other models exist but the PT comes to my mind first.


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