Thread: Choices, Choice, Which dust extractor?

I personally would go for the 1 micron filter cartridge, plus make a Thien Dust Separator so that all the dust goes in it, and not in the filter bag. As you said, you only have one pair of lungs, so why risk them for the sake of a bit higher flow capacity. You cannot compromise on safety!

regards,
Jill

If you can put your DC outside your shed you do not need any fancy filters and it will be infinitely better for you than ANY filter used on a DC inside your shed.

That way you can afford the next biggest CFM unit.

1 micron filters are practically useless for capturing the really nasties which are <1 micron.

Running a 1 micron filter inside a shed is like disinfecting a hospital for 20 species of deadly bacteria but the disinfectant is only killing 1 or 2 species. It looks good and smells nice but the nasties are still there.

I recently bought a DC3 unit from Timbecon with the filter cartridge as well. I also use a cyclone separator and I leave the dust extractor outside the workshop. It may sound like overkill but the filter cartridge is way superior to the cloth bag because it has around 7 times the filtering area than cloth. Consequently it is more effective in dust extraction. The separator ensures that the dust extractor will not lose efficiency and not require cleaning any time soon.

I don't think people realise how much crud gets through the cloth bags until you get a cartridge filter. Even while in the workshop, there didn't seem to be a dust build up over the time like there is with the cloth bag, and the air is soooo much cleaner.

It's such a relief not to have fine dust everywhere and to get the maximum suction out of the dust extractor.

Personally i would get the DC7 if you have the space, just wheel it outside when you use it and save up for some pleated filters.

The larger unit has a solid collection hose making the unit sturdier. The higher CFM will do a better job of collecting dust at the source and it will also allow longer runs if you do ever decide to run fixed ducting in the future.

Good luck.
joez

Ok, so as the responses seem to be varied and somewhat valid to common sense, i've decided to take the scientific approach and look for studies regarding wood dust, and their particle size.

Lo and behold, such a paper was indeed done by IARC, the International Agency for Research on Cancer.

Of note in this paper was that

Holliday et al. (1986) used an optical microscopy method (see section 1.3.1) to count paricles in varIous size ranges and found that 61-65% (as calculated by the United States National Institute for Occupational Safety and Health, 1987) of the particles measured 1 - 5 um.

Thats on page 88.

Page 89 - 92, also yields more studies on dust particle size, of which both the Optical Microscopy, Scanning Electron Microscope and a few other techniques, yielded approximately the same findings, around 60% of the particles from sawing/sanding/planing are in the 1-5 um range. That said various other studies (typically all of the ones using cascade impactors) also show that they vary from 10 - 20 um. Although i can't say i understand fully how the cascade impactor works, to me a SEM seems to be the more accurate tool.

On a side note, here's another interesting exerpt from the paper (pg 54),

Sharp, thin blades produce less wood dust by volume because the kerf, the cut made in the wood, is narrower, but the particle sizes are also likely to be smaUer.

The rest of the paper deals with cancer related stuff in the woodworking industry, and for the most part i've skipped through them.

So yeah food for thought, i think i myself would most definitely go for the DC3 but with the air filtration unit.

Also thanks for all your responses so far.

Cheers,
Bismar

Good thinking Bismar, and use a dust separator and also wheel the DC3 it outside your shed to use it, and you are away! Best of all worlds

good luck,

Jill

No one has ever regretted breathing clean air and staying healthy, so I think you will be happy with your decision.

Bismar, don't be fooled by the 1 micron filter, it doesn't capture 100% of the 1 micron dust anyway and then there are the smaller still particles to worry about as well. BTW I have used an impactor and SEM and the impactor is more accurate is assessing dust in a bulk situation.

For wood dust situations a high air flow and directing the dust away from the operator is far more important than filtration capacity/size as high airflow captures more dust at source.

If you only have a limited budget spending it on a bigger DC and getting the dust outside the shed is definitely the way to go.

In high wood dust situations I would much rather have a 5HP DC and vent via a 30 micron bag outside the shed, than a 2HP DC connected to a 0.1 micron filter inside the shed. If I had the $$ of course I would have 5HP DC venting to a 0.1 micron filter outside the shed. Actually 0.1 microns is a bit of a waste, probably just a cyclone would do it - ie no filter even needed.

The reason for this is that 1HP DCs simple cannot grab enough of the dust as it is made by most machines. What ends up happening is this dust is sprayed all over the shed and the small DC takes a long time to collect it all up, ie up to 20 minutes after the dust has been made, This also means running your DC much longer than is necessary.

We have plently of woodworking experts on this forum but this is really a health matter. Well, I am not a doctor but I would be surprised if any health professional would agree that you should not worry about the massive amounts of 1- 5 micron particles getting into your lungs. Particularly when working with some potentially dangerous species.

Remember also it rains in Australia and the DC outside is not always an option.

I know the differences from my own experience - I have only had issues with asthma with the felt bag. In fact I am surprised they are allowed to be used indoors at all under Australian Standards

Mmm, i don't own and can't afford a shed.

I'm working in the garage and the dust collector was always planned to be outside in the garden.

Besides if i did have the higher compressor in my garden, i'll probably need to totally seal it away from the garage, as the pressure differential would be doubled and thus a higher rate of backflow of the non filtered dust into the garage.

Also the Dc7 has some weird specs. The difference between those two is only 1 HP, and yet the CFM is rated at twice as much. Which is kinda odd, seeing as the pump should need to work four times (if it was 2HP) as much as the surface area is twice as much, and twice the CFM.

With that in consideration, would it still make sense to buy the DC7?

Also BobL, you note that the impactor is more accurate, thus correlating to the findings that the majority of the particles are much bigger then 1um, yet maintain the 1um will be not 100% efficient and will let smaller particles through. By that logic wouldn't it make sense to get the 1 um as the 5um will not be 100% efficient either?

Sorry if i seem to be questioning your advice as i'm rather confused.

Thanks,
Bismar

I'm with BobL on this one.

I would buy the one with more grunt.

I havent heard of too many folks complaining about too much suction.

Also if u end up buying something like a thicknesser at some stage then the extra suction will be most welcome. My 2 Hp copes ok with mine, but a 3 would be better of course.

save up a bit longer and buy the one with the most hp and suction, being the dc-7, then get 2 of the cartidge filters and fit them to it, then park it in the garden so it exhausts to atmosphere well away from where you are working.

it would seem this is one way to make sure you dont breath in all the crap in the air.

down the track get an air filtration device and put it in the garage as well, this will clean up whatever the dc doesnt.
and if you are still concerned, wear a dust mask while working.

im not being silly or sarcastic but if you want to protect your lungs then this is one way to do it, when assessing for OH&S purposes which it would seem you are pretty much asking for, you must identify the hazard (dust) then assess the risk (health issues and the degree of the outcome due to the of exposure to the hazard) then work out how to eliminate or reduce the hazard and risk to acceptable level, either by engineering, environemnt, ergonomics, ppe etc.
in this case engineering would be 1 micron filter on the biggest bestest dc you can afford, environment would be parking it outside and ppe being the dust mask you could wear. further engineering and environment would be the installation of filtration to the garage in which you work.

but this is all pie in the sky if you have limited funds, as somebody said if we could afford it we would all have massive big cyclone units outside with big hp motors and enough suction to pull out hair out from accross the room (well not exactly said like that but anyway you get the drift).

I can't give you any specs, but I have the DC7 from H&F and it has plent of suction. Contected to my router table, I see no saw dust. It all goes up the 4 inch duct and that is that.
What's best for you I could not say, but I am impressed by the performance of the DC7. It is value for money.

Originally Posted by Bismar

Mmm, i don't own and can't afford a shed.
I'm working in the garage and the dust collector was always planned to be outside in the garden.
Besides if i did have the higher compressor in my garden, i'll probably need to totally seal it away from the garage, as the pressure differential would be doubled and thus a higher rate of backflow of the non filtered dust into the garage.

The really fine particles (<1 micron) can be suspended in the air for some time (which is why a DC located outside a work area should be run for some time [20 minutes] or so after the last dust making activity) and yes it's not ideal putting your DC immediately adjacent the main opening to your working area as some of the fine dust will just drift back into the shed. The best place is on the other side of the wall opposite the main opening of the work area and preferably on the usual downwind side of the shed opening. I have my DC in a polycarbonate lean-too outside the shed opposite my door where the 30 micron bag . The number of fines that drift back into the work area depends on the air flow around the shed. Either way just getting the fines outside produces a significant dilution effect.

Also the Dc7 has some weird specs. The difference between those two is only 1 HP, and yet the CFM is rated at twice as much. Which is kinda odd, seeing as the pump should need to work four times (if it was 2HP) as much as the surface area is twice as much, and twice the CFM.

The area doesn't matter if it is large enough. CFM should ~scale with true HP (I wouldn't believe what is written on any cheap motor because the manufacturers just write on there what the buyer wants to read) if but it depends how well the DC is made. A well made DC determines the pressure gradient that it can maintain so a quality DC can easily have twice the CFM compared to a cheap DC even at the same claimed HP rating.

Also BobL, you note that the impactor is more accurate, thus correlating to the findings that the majority of the particles are much bigger then 1um, yet maintain the 1um will be not 100% efficient and will let smaller particles through. By that logic wouldn't it make sense to get the 1 um as the 5um will not be 100% efficient either?.

Correct - used in a shed a 1 micron bag should be superior to a 5 micron bag but you need to look at the actual efficiency ratings..