Thread: Comparing 2 dust extractors. Which to buy?

The real question to ask is "will there be enough air flow" to collect enough fine dust, because manufacturers specifications are not representative of real air flows.

Both units use 2HP impellers and 4" ducting so I can tell you right away there simply won't be enough air flow to collect enough fine dust.
Then on top of that they add cyclones which will further reduce airflow.

You would be much better off putting that sort of money to at least a 3 or 4HP DC and 6" ducting then at least you'll know you will have enough air flow.

BobL, this whole operation is a compromise with many limitations. There are space constraints, there is a limit to how much can be spent and there is a limit to the amount of power that can be supplied by the generator that will run the operation. The starting load of a 4HP induction motor is probably beyond the limits of the 8Kva generator that I have to run the whole show. Ducting will probably have to be whatever I can get out here in the bush, 100mm plastic sewer pipe from Bunnings springs to mind. Basically I need to get the most efficient system for what I can afford and run. With the W381 I can move the dust extractor close to the machine and cut down on (or eliminate) ducting.
Which is the more efficient of the two systems? I tend to favor the W381 for it's compactness and shorter air flow path.

The method of towing a DC around to machines is an inefficient way of handling fine dust because it results in the following ALL staying inside the shed.
1) the fine dust that escapes collection at source - 4" ducting doesn't have a hope of collecting all the fine dust from most machines
2) the fine dust that gets through the DC filters
3) the fine dust from leaks from a DC (they all eventually leak)

Hence the best location for eliminating fine dust permanently is to at least locate the the DC outside a shed and given you have space constraints this makes even more sense.

When the DC is outside a shed, ducting has to be run but if you run 4" ducting you will get less flow so all you will end with is a chip collection system but at least whatever fine dust is collected is not recycled back into the shed.
If 4" ducting is all you can do then we have to work with that.

Those cyclones will be no better in terms of air flow than a 2HP DC ($370) with a plastic drum chip collector.

Hence to minimise the amount of fine dust my recommendation would be as follows
Setup a 2HP DC ($370) with a plastic drum chip collector outside the shed and run 4" ducting inside the shed - i.e. set up a basic chip collection system
Setup beefy passive and forced ventilation to constantly sweep fine dust out of your shed shed. By this I mean opening up all doors and windows and adding a couple of big fans to force air through the shed. This should not only be done while a machine is running but for some time (20-30 minutes afterwards) You will just have to put on an extra jumper in winter.

Whereabouts in the NSW bush Old Hilly? Bob has offered very good advise. If you followed his advise the K047 is basically what you would end up with, albeit with some additional material getting through to the filter, for a lot less money. It looks like both of the systems you have linked to may be capable of being converted to a 150mm inlet. If that is the case, like you, I would favour the W381; it avoids the inefficiency introduced by the 100mm flexy from the cyclone to the DC and the 125mm flexy from the fan to the filter and collection bag. It would be easy to make it far more efficient than the K047 simply by upgrading the inlet to 150mm, or if not possible at least to 125mm.

If you must use the DE in the shed a pleated filter would probably provide some worthwhile benefits, but locating it outside the shed would be far preferable. If you can possibly do it 150mm PVC is capable of providing more than twice the flow of 100mm.

Just a few random thoughts.

There are 3hp DC currently available for around the $400 mark - EDIT: ops that was for a single phase, 3 phase are a bit dearer.

Is it possible to to run a VFD from a Generator? Assuming the generator is suitability large enough and 8KVA sounds like it would be? Bobl ????

A soft start VFD would keep startup current way down and overcome that limitation. A 3hp DE runs at 10A or less depending on air flow restrictions.

Some online plumbing suppliers deliver for around $40 interstate, you may be able to get 150mm ducting and delivery for less than you would pay for 100mm stuff from some local hardware and plumbing suppliers? worth checking.

If machines are not too big perhaps they could be made moveable, therefore keeping the cost of ducting and bends to a minimum? Could always add more later.

Maybe the above is not doable, in any case as Bob said, get some good fan driven cross flow ventilation going regardless - it can really make a difference to your health.

Originally Posted by aldav

If you can possibly do it 150mm PVC is capable of providing more than twice the flow of 100mm.

In theory it's closer to 3 times the air flow - BUT - the DC must also be capable of moving that much air.
A 2HP can only move about 80% more air, a 3HP about 2.5 times so it takes a 4HP or more machine to get the full x3.

RE Running a 240V VFD
I was going to suggest that because of the soft start option but am not sure how a VFD would operate from a genset.
We'd need to know if it's "real" kVA or a "chinese" kVA
It would probably be OK but its going to be border line.

Originally Posted by BobL

A 2HP can only move about 80% more air

So with 150mm ducting a 2hp has the capability to move 180% of the air of the same machine with 100mm ducting? Sounds like a worthwhile improvement to me.

The DC will be movable and may be able to be located in an annex outside the shed, if not then if it is on wheels it can be moved. Short lengths of 150mm pipe may be available (galv. rainwater downpipe springs to mind) but I need to check on this. It seems that my suspicion that the more expensive machine may be more efficient due to it's more direct (shorter and less bends) was correct. If I mount the machine outside the shed with some sort of "feed-through" going through the wall close to where the machines will be working I should be doing OK. I realise that with my budget I will never get all the dust that these machines make but if I can get most of it, that will be a start. Then if I can find a comfortable dust filter mask that works without fogging up my glasses I will be really happy!

Originally Posted by aldav

So with 150mm ducting a 2hp has the capability to move 180% of the air of the same machine with 100mm ducting? Sounds like a worthwhile improvement to me.

Also provided it is modified according to the sticky thread at the top of the dust forum.

In terms of forced ventilation how about these courtesy of the "grow your own" industry.
https://www.ebay.com.au/itm/Exhaust-...4AAOSw44BYiBJK

Two of these 6" fans will produce close to 20 room changes per hour for a 2.4 x 6 x 4 m shed.
$114 each, very quiet - ~33 db and draw about 50W each!

Using 8" fans would produce 30 room changes per hour, 63 dB and 128 W each
I reckon these would solve fine dust problems in most DIY situations

Looking at the two deals I suspect if you must choose one the W318 is the better bet as most modifications to the standard 2hp dusty essentially coverts it to what the W318 is setup to do out of the box. However as Bob has said numerous times in the past the cyclone isn't very efficient. If you're not entirely convinced the biggest clue to how efficient the Hare and forbes cyclone is, is look at the size of the collection bag attached to the filter and compare that to the collection box of a Clearvue cyclone. The claim that the cyclone separates 99.91% of dust is most likely calculated by weight eg chips weigh more than dust as quite abit of it is pumped out the back not to mention the stuff that isn't extracted to begin with.

Also I'd avoid the package deal, all the accessories that come standard are not very good quality and will end up on a shelf collecting dust.

Also I'd like to add for the price of the the W318 unit you could definitely buy any standard 2hp dust extractor modify it, and buy probably all your ducting requirements and still have plenty of change left over to buy another machine for the shed. You don't need the cyclone especially if its located outside.

If you can arrange openings in the wall opposite to where any fans are installed you'll get the best 'bang for your buck' out of them. Openings should be considerably bigger than the nominal fan size for the best result. The W318 won't be the best DE system around, but if you can use 150mm duct and get the DE out of the shed it'll be a lot better than what many others are using.

Originally Posted by tonzeyd

Also I'd like to add for the price of the the W318 unit you could definitely buy any standard 2hp dust extractor modify it, and buy probably all your ducting requirements and still have plenty of change left over to buy another machine for the shed. You don't need the cyclone especially if its located outside.

Depends on how much woodworking you do and whether you'd rather spend time cleaning filters or doing woodwork. One of the beauty's of cyclones and pleated filters is that you can give the filter a quick tickle and get back to work pretty quickly.

I purchased my pleated filter for a 2hp dusty (and cyclone) used it for about 6 months with regular turning of the paddles, did this quite religiously before and after every use. Thought everything was fine until i went to replace the bags. Whilst putting on the new bag a chunk of dust dropped from the pleated filter. Thought to myself... that was odd and decided to remove the filter and stick my head into the filter to take a look inside. Quickly became apparent that turning the paddles has limited effect on cleaning the filters and promptly started looking for an alternative. Ended up with a 3hp bagged unit and find that shaking the upper bag regularly removes alot of the caked on dust and now the 2hp unit sits quietly in the corner not doing very much.

Plus i now notice less dust floating in the air and when i do my regular blow out of dust with the garden blower, hardly any dust gets blown around whilst previously the neighbours would have definitely lodged a complaint if they saw what I was blowing out of the shed.