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Homemade cyclone extractor.

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IanB

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I've just bought the same Nilfisk vacuum - I hadn't thought of adding a cyclone but it seems too good an idea not to, thanks for the explanation!
 

skeetstar

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Inspired by folks comments on here I bought one of the Chinese cyclones, same as those pictured earlier.
Its is connected to a Henry, but the results I have achieved today are pitiful.
I would estimate that a third to a half of the dust is getting past the cyclone and into the vac,

I have a large blue ex chemical drum for a collector. The Henry collapsed that when I first connected it (using my homemade cyclone system copied from youtube last year) so I drilled a few relief holes in the lid. I imagine that the joints to the cyclone aren't 100% airtight either. ... would that be the cause of the problem?

I understand the principle of centrifugal force on which the cyclone works, but I'm not sure what effect sealing all the joints will have...

greater suction resulting in more waste being pulled into the vac, or greater suction resulting in greater centrifugal effect and thus less stuff in the vac.?

Any one got any thoughts?

And yes I do plan to seal the joints, today was just a prelim test.
 

Jamesc

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From my limited experience I would say you have a restriction in the system to colapse the blue bin. Are you using full size hoses, is anything blocked?
To get a cyclone to work you want maximum airflow. The faster the better.
 

Dee J

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so I drilled a few relief holes in the lid. I imagine that the joints to the cyclone aren't 100% airtight either. ... would that be the cause of the problem?
The system only works properly if the drum is sealed. Holes in the lid set up an airflow from drum to hoover taking the dust the wrong way. Drum pressure needs to be lower than atmospheric.
 

Sachakins

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Inspired by folks comments on here I bought one of the Chinese cyclones, same as those pictured earlier.
Its is connected to a Henry, but the results I have achieved today are pitiful.
I would estimate that a third to a half of the dust is getting past the cyclone and into the vac,

I have a large blue ex chemical drum for a collector. The Henry collapsed that when I first connected it (using my homemade cyclone system copied from youtube last year) so I drilled a few relief holes in the lid. I imagine that the joints to the cyclone aren't 100% airtight either. ... would that be the cause of the problem?

I understand the principle of centrifugal force on which the cyclone works, but I'm not sure what effect sealing all the joints will have...

greater suction resulting in more waste being pulled into the vac, or greater suction resulting in greater centrifugal effect and thus less stuff in the vac.?

Any one got any thoughts?

And yes I do plan to seal the joints, today was just a prelim test.
Hi, some photos would help.
You have got the hoses connected right way? The vacuum hose to the top of cyclone and your collection hose into the side of cyclone?
 

skeetstar

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Here's a photo. The primary hose is a standard Henry vac hose. I'm running the Henry without a bag. You can see the relief holes I've drilled in the lid, without those I think the bin would collapse, even though it is a pretty sturdy plastic.
The secondary hose is 25mm internal diameter. It is quite long, maybe 3 metres.

When switched on the vac does distort the bin a little, and I can watch it flexing as I switch the vac on and off. The hose connections to the cyclone are probably 98 to 99% airtight, I am sure that the cyclone to lid attachment is 100% airtight.

So if I close all the gaps with silicon etc and tape over the relief holes, and strengthen the bin to stop,it collapsing, do folks think that would be beneficial?
 

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Tris

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The 25mm hose is the problem. Needs to be the same diameter as the hose to the 'Henry' to stop the bin collapsing. At a push you might be able to use the metal pipe that comes with the Henry to allow air in on the vacuum side to balance the flow (opening the plastic valve) but I don't know if that will be enough
 

Sachakins

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Your hose is way too small. I've put 50mm on inlet and out let and works fantastic. Put bigger hose on, then plug up all your holes and leaks.

The 25mm hose is actually causing so much constriction, its acting as if its blocked.
 

Robbo3

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Just to repeat what has already been said - the drum needs to be as airtight as you can make it so you will need to seal up the holes that you made. Change your hose to match the Henry then add a Pressure relief Valve to the drum - see post 82 in this thread
- Tips & Tricks
You should also use a bag in the Henry so that it catches any dust that does happen to make it's way through the system & doesn't exhaust it back into the air that you are breathing.
 

Davey44

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Inspired by folks comments on here I bought one of the Chinese cyclones, same as those pictured earlier.
Its is connected to a Henry, but the results I have achieved today are pitiful.
I would estimate that a third to a half of the dust is getting past the cyclone and into the vac,

I have a large blue ex chemical drum for a collector. The Henry collapsed that when I first connected it (using my homemade cyclone system copied from youtube last year) so I drilled a few relief holes in the lid. I imagine that the joints to the cyclone aren't 100% airtight either. ... would that be the cause of the problem?

I understand the principle of centrifugal force on which the cyclone works, but I'm not sure what effect sealing all the joints will have...

greater suction resulting in more waste being pulled into the vac, or greater suction resulting in greater centrifugal effect and thus less stuff in the vac.?

Any one got any thoughts?

And yes I do plan to seal the joints, today was just a prelim test.
Hi there. I did almost exactly the same as you and found that what I had believed to be a high-density plastic drum (with a screwed on lid and seal) would be adequate for the purpose.

Initially I used my elderly ex-Wickes wet and dry vac. It worked well, leaving around 80% of the material collected in the intermediary cyclone/barrel. However, it did collapse the sides of the barrel significantly in the process.

Having read up on the subject and read posts from others who had gone a similar route I made and fitted a simple pressure relief valve in the lid. It did permit some drop in negative pressure in the drum but obviously needs greater capacity through the relief valve (i.e. larger valve orifice or less strong spring - or both) to raise the negative pressure and enable the system to work more effectively.

I would add that fitting the relief valve did NOT reduce the efficacy of the cyclone and the barrel. Since this time I have substituted one of the cheapo ash extractors (ex-Aldi or Lidl?) which produces less negative pressure in the line and less barrel distortion.

The trial goes on!
 

HamsterJam

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Any air getting into the drum will reduce the dust collection efficiency.
This is because that air eventually goes up the cyclone pushing any dust back up and into the vac rather than letting it fall into the collection bucket.
 

heronviewer

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Would these cyclones work with a 4" hose on either side of them ? I have an old AEG drum extractor that I use to extract from a planer/thicknesser, band saw, table saw and spindle moulder - all using 4" hose. I'm sure adaptors from 4" to 2" are available. I need to keep a cyclone small because of workshop space.
 

Sachakins

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Would these cyclones work with a 4" hose on either side of them ? I have an old AEG drum extractor that I use to extract from a planer/thicknesser, band saw, table saw and spindle moulder - all using 4" hose. I'm sure adaptors from 4" to 2" are available. I need to keep a cyclone small because of workshop space.
Could you fit this axminster cyclone? 4" fittings
 

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Robbo3

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Having read up on the subject and read posts from others who had gone a similar route I made and fitted a simple pressure relief valve in the lid. It did permit some drop in negative pressure in the drum but obviously needs greater capacity through the relief valve (i.e. larger valve orifice or less strong spring - or both) to raise the negative pressure and enable the system to work more effectively.
I would add that fitting the relief valve did NOT reduce the efficacy of the cyclone and the barrel.
Something not quite right with your system or you haven't explained it properly :).
In normal use the PRV should be closed with no leaks. The PRV should open just before the vacuum is great enough to cause the sides of the drum to collapse. It is a safety device not an air flow regulator.
If the drum is on the point of collapse during normal use there is an inbalance in the air entering & leaving the system. It should flow through freely without any restriction. Quite often you can tell by the drop in pitch of the motor if the vacuum cleaner hose is disconnected from the cyclone.
 

sometimewoodworker

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@skeetstar you have several problems most have been pointed out but to repeat.
1) your dust receiving bin is not strong enough you have to introduce reenforcement into the sides, you will need several rings.
2) the bin needs to seal completely, your holes in the lid are causing the dust to bypass the bin. You will probably need to reinforce the lid as well as seal it.
3) the small hose into the cyclone is not doing you any favours but if you completely seal and reinforce the bin it can work.
4) the output hose from the cyclone is far too long it should be as short as possible also if possible you should use smooth internal hoses because the ribs are reducing airflow.
5) if you can use a larger input to the cyclone it will be better but the small hose will still work.

a points to remember; the long ribbed output hose reduces efficiency, a long ribbed input hose reduces efficiency, the cyclone reduces efficiency, a small input hose reduces efficiency, a non sealed bin reduces efficiency,

Can it work? Yes absolutely. I have a setup that is somewhat similar in principle. But with shorter ribbed hose and the connecting hoses are smooth internally.
416F9520-87DF-4C92-9AAB-81911B2ADD5D.jpeg
 

sometimewoodworker

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Hi there. I did almost exactly the same as you and found that what I had believed to be a high-density plastic drum (with a screwed on lid and seal) would be adequate for the purpose.

Initially I used my elderly ex-Wickes wet and dry vac. It worked well, leaving around 80% of the material collected in the intermediary cyclone/barrel. However, it did collapse the sides of the barrel significantly in the process.

Having read up on the subject and read posts from others who had gone a similar route I made and fitted a simple pressure relief valve in the lid. It did permit some drop in negative pressure in the drum but obviously needs greater capacity through the relief valve (i.e. larger valve orifice or less strong spring - or both) to raise the negative pressure and enable the system to work more effectively.

I would add that fitting the relief valve did NOT reduce the efficacy of the cyclone and the barrel. Since this time I have substituted one of the cheapo ash extractors (ex-Aldi or Lidl?) which produces less negative pressure in the line and less barrel distortion.

The trial goes on!
Your fixes addressed the wrong problem and with 20% bypassing the cyclone collection it is very badly inefficient. Reinforce the drum, eliminate the pressure release valve and with correctly sized hoses you should have almost 100% collection into the bin. Putting in less good extraction (ash extractors) is the wrong answer.
 

Robbo3

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@skeetstar you have several problems most have been pointed out but to repeat.
1) your dust receiving bin is not strong enough you have to introduce reenforcement into the sides, you will need several rings.
2) the bin needs to seal completely, your holes in the lid are causing the dust to bypass the bin. You will probably need to reinforce the lid as well as seal it.
3) the small hose into the cyclone is not doing you any favours but if you completely seal and reinforce the bin it can work.
4) the output hose from the cyclone is far too long it should be as short as possible also if possible you should use smooth internal hoses because the ribs are reducing airflow.
5) if you can use a larger input to the cyclone it will be better but the small hose will still work.

a points to remember; the long ribbed output hose reduces efficiency, a long ribbed input hose reduces efficiency, the cyclone reduces efficiency, a small input hose reduces efficiency, a non sealed bin reduces efficiency,

Can it work? Yes absolutely. I have a setup that is somewhat similar in principle. But with shorter ribbed hose and the connecting hoses are smooth internally.
I disagree.
The catchment container can be flimsy plastic & should not collapse as the air flows freely through the system. If it starts to collapse then the air is being restricted somewhere within the system & causing a vacuum. Strengthening the dust container is not the right answer.
Much better to sort out the restriction & add a PRV as a precaution against whatever is being sucked up causing a blockage. :)
 

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