Shop vac modifications

[Niki]

Good day

I have a home vac that I'm using as a shop vac. The problem is that first, it's getting full very quickly and second, the original build-in filters are clogging very quickly.

I would like to share with you the modifications that I made to overcome those problems.

Regards
niki

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[Philly]

Looks good, Niki!
Guess you won't need to empty that one for a while :lol:
Philly

 

[Jorden]

Now that is an idea I like - thinking about swapping the plastic bag on my Record dustX for a solid container

Dennis

 

[Barry Burgess]

Nikki your filter will block up quit quickly. I think you will get better results if you use a sinle pipe out of the drum to the vacuum. This is the one that I got the best results from

TOP

Bottom

Barry

 

[Niki]

Thank you for your comments

It’s a 100 liters barrel and the good thing is that it can “eat” everything (even gravel) without any effect on the two build-in filters (my wife is using it to clean her garden, the car etc).

After some experience, I decided to use two layers of those “filters” to have better pre-filtration.

niki

 

[Derek Willis.]

Mike Garnham made something similar a while ago, and I copied it, with a wooden box to contain the rubbish, an in and out pipe connected to the vac, filters on the vac stay clean annd no rubbish in the vac container, I wouldn't be without it now,
Derek.

 

[John. B]

Do you know,
there are some quite extraordinary inventive chaps on these forums.
Makes one feel quite humble sometimes. =P~=P~=P~=P~

 

[slemishwoodcrafts]

i have a Record RSDE1 extractor and got fed up with filter clogging and being a pain to clear out.

I built a mini cylone for it, using a road cone for the conical part and some 6" soil pipe for the main cylinder. Its on the same principle that you guys are talking about. I'll post some photos later

Regards

Michael

 

[wizer]

I've got a Triton dust bucket in the loft I've never used. I must have a clear out one of these days.

 

[Niki]

For all those that wants to build the Cyclone with the Triton bucket, just go to the Aussie forum and you'll find all the planes that Sturdee (Peter) made a few years ago (WISeR ?????? :shock: :shock: :shock: )
http://www.woodworkforums.com/archive/i ... 21382.html

As for me, I'll never try to make a cyclone with a home/shop vac after I read on "Woodnet" one Engineer - that works in DC factory - saying that a shop vac is too small to be an effective "Cyclone" and that's the reason that he is not converting his shop-vac to cyclone.

I would like to explain my point of view, why I selected to go to this kind of design and not cyclone.

When the air is moving on a surface, the speed of the layer immediate to the surface is zero, the next layer has higher speed, the next layer, higher speed and so on till the airspeed equals the airstream speed.

This layer, that the airspeed changes from zero to the airstream speed is called "Boundary layer" and cannot be escaped...of course if the surface is rough (like those corrugated or spring like vac hoses) the situation is worse.

The Boundary layer actually reduces the effective diameter (I mean - the free stream dia) of the hose.
The longer the hose, the more thicker the Boundary layer becomes and more reduction.
All this causes what is called "Momentum loss" and reduces the motor efficiency.
So, the shorter the hose - the better motor efficiency....

Another factor that reduces the motor efficiency and causes a Momentum loss is Bents or Elbows....every deflection of the airflow, creates turbulence that are again slowing the airspeed and causing a Momentum loss....the bigger the bent angle - the bigger the turbulence....
Same will be while forcing the airstream to swirl around the cone - somebody shall have to pay the for it and again it will be the motor.

From looking at the flow pattern of the cyclone, the "clean" air is sucked out from the center of the cyclone but, it looks to me that this "clean" air is not so "clean" otherwise the filters would not fill with so much dust...I mean, the fine dust will still find it's way to the main filter.

So, what is different in my design...
* I use very short hose (1 Meter) and smooth inside wall.
* the dust, is pushed at an angle to the barrel wall that swirl the air but the air speed is reduced dramatically because of the "diffuser chamber" effect.
* The air is passing through 2 layers of "Pre-filter" that removes almost all dust (except some microscopic particles that I cannot see).
* After the pre-filter, the very small particles that manage to escape will be stopped by the main filter. (on my vac, there is another filter just before the air enters the motor so actually I have 2 main filters.

It's true that the Pre-filter will clog very fast but because of the large area, I still have enough good suction to work 15~20 minutes continuously on the table saw or router...BUT>>>>

I made a "Pre-Filter Cleaner" that I can clean and restore the filter to almost 100% efficiency and all that from outside, even without opening or dismantling the vac.
So, every now and than, I clean the pre-filter (takes 2~3 seconds) and continue to work till the bucket gets full.

I don't have to open the barrel till the barrel is full...a little bit less than 80 litters...and I have positive indication when it's full.

Best regards
niki

 

[ivan]

Niki, your Woodnet engineer is talking rubbish!

The best selling UK domestic vac cleaner (for the house) is the Dyson, which has an exclusive selling point All cyclone, No bags! Whilst looking into this, including Bill Pentz' website, I found papers on line about the use of small cyclones to remove radioactive smoke particles from the air in research laboratories. The Dyson vac has 8 cyclones about 4 cm in diameter. In the UK you can often find them at the recyling tip (they are not very reliable even though popular) and quite interesting to experiment with.

 

[dh7892]

But isn't Niki talking about the distance from the motor to the top of the cyclone? In a Dyson (I've got one) the motor sits at the top of the cyclone chamber so there is no tube between the motor and the cyclone box.

I think that we're just talking here about how far you can separate the "pump" from the cyclone chamber and still create an effective cyclone.

I can't see any points in Niki's email that I dissagree with (although how much they affect the performance I'm not sure).

Also, whilst the Dyson has "no bags" it still does need a fine filter (which needs regular changing) so I'm not really sure why that's any different to a bag.

Good idea to try experimenting with a scrapped Dyson though.

 

[ivan]

The Dyson does have an after-cyclone filter, although you don't have to change it very often in a domestic setting. What they don't say in ads of course is how much air resistance the tiny cyclones/air pasages cause - for all I know as much as a bag! I did experiment with a broken Dyson upright's cyclones, which did capture a lot of fine stuff from the workshop vac filter. However the main case was too cracked (ex recycling tip) for permanent use - did convince me to keep an eye out for another at the tip.

 

[johncs]

Niki, your Woodnet engineer is talking rubbish!

The best selling UK domestic vac cleaner (for the house) is the Dyson, which has an exclusive selling point All cyclone, No bags! Whilst looking into this, including Bill Pentz' website, I found papers on line about the use of small cyclones to remove radioactive smoke particles from the air in research laboratories. The Dyson vac has 8 cyclones about 4 cm in diameter. In the UK you can often find them at the recyling tip (they are not very reliable even though popular) and quite interesting to experiment with.

A domestic vacuum cleaner doesn't have the capacity to remove the volume of dust created by modern power tools and machinery.

Here's Bill's page:
http://www.billpentz.com/


I suggest people read it and try to understand it before dismissing it.

 

[navypaul]

niki has some valid points based on basic fluid dynamics, what is described is parasitic drag- the combination of surface friction and interference drag (things in the air stream such as the coils in the tubing). lift induced drag when a moving object redirects the air it is travelling through, in this case the moving air and stationary object - a bend or such thing) all need to be addressed in a extraction system. these are all well documented things in aero engineering (my job) and with out some of them aircraft would not fly, and others you try to reduce to as low as practical. there are differences such as is the air stream being pushed or pulled, pushed will usually create more problems than pulled, damage to motor boat props is a prime example of this. i believe vacuum type extractors are better at this type of air moving (although, of this i have no mathematical proof)

ultimately it will be the motor that pays which is how aircraft fly, the thrust must be greater than the total drag for it to get off the ground so must the extractor motor be powerful enough to provide enough moving air to overcome all the drag which works to slow the air, you can have all the drag in the world but if you have a huge engine you will remove waste product, it just depends how much. as for cyclones they seem to work but seem a lot of effort to just keep a filter clean, when it seems that the smaller the particle the more influence the the air flow will have on it, gets thorough and they are the ones that blog my filters up.

paul