Fence or Ambulance

I could have also titled this “Source or destination”

Would you prefer a fence at the top of the cliff, or an ambulance at the bottom?

Following on from the previous article, there is one thing that has been annoying me with heavy construction, specifically in occupied buildings. Unlike the precautions I take in my workspace (shed), there is so little (as in “none”) control of dust at the point of origin – the construction industry appears to rely on cleaning up afterwards rather than dust minimisation techniques.

While sanding down some of the walls in my home (part of the whole fix-up – I’m getting better at plastering), I’m using the Festool ETS 150/5, with a Cleantex CT36 and Oneida cyclone.  Just on startup, if you don’t wait for the vac to kick in, you can physically see the cloud of plaster trying to billow out, before being sucked straight back into the various ports on the ETS.  The rest of the job, there is no dust, nothing to clean up, even when sanding in the walk-in wardrobe – there was no dust on the clothes at all.  Let alone in my lungs.

Something like the industrial sized Microclene unit for a worksite

Microlene MC3000

or a small unit suitable for a workshop


This is one decent step towards capturing dust that is produced before it fills the room and settles on all the surfaces.

You can improve the collection further by adding a shield to the collector

mc1000-2or even place the unit right at the source of generation.

micro-3Whether that be an air filtration unit nearby, or on-tool dust collection, or a combination of both.

One way or the other, the results are always better when you actively mitigate dust production at the source, rather than cleaning up later.  What would you prefer – using and cleaning a filter, or using your lungs as that filter?

Wearing pleats in the workshop

As a general rule, wearing pleats in the workshop is not the best idea. Other than being just a little too frilly to be shed-like, you’d get a lot of really weird looks from visitors!


Of course, there is a place for pleats in the workshop, and that is in the cartridge of the dust extractor. So why would something frilly be a practical accessory in the workshop?

Many dust extractors use a cloth bag. Cloth bags are great. They are cheap, which is great. They are easy to clean, which is great. And they are great at spreading as much fine dust as you’d ever not want to see around the workshop. Sure, the large stuff gets captured, but that is stuff you can sweep up with a broom and shovel, so one way or the other it is easy to dispose of. The fine stuff will get you every time. In Australia, all wood dust is regarded as carcinogenic.

Many cheap dust extractors would have a cloth bag at the top and bottom. Awesome – two cloth bags to let the dust fly!

sealey-dust-extractor-2hp-240vIt is probably not fair to badmouth cloth bags too much – reasonable ones are running 5 micron, which isn’t much worse than what a pleated filter can achieve anyway.

So what is the advantage of a pleated filter?

A dust extractor pushes through a certain quantity of air. And what goes in, must come out. If you have a cloth bag, the air that leaks through the holes in the cloth to equal the amount of air that is sucked in the hose. As the holes clog, the total amount of air that will flow will decrease. So a filter that is easy to clean is an important consideration. Cloth bags can be banged out, blown out with compressed air, even washed in the washing machine. The limiting factor though, is the total surface area of the filter (the bag).

If you increase the surface area, the total amount of air that will need to pass through doesn’t change, so as the surface area is bigger, the holes can be smaller and still achieve the same through-put of air.

Where it comes to cleaning, pleated filters have a system where you wind or move a handle, that causes the internal baffles to be impacted, dislodging dust and allowing it to fall into the lower half (collection) for the extractor.

Pleated filters used to be only available on expensive dust extractors, but these days you can pick one up to retro-fit to your machine for under $180.

Considering a cloth bag replacement is around the $80 mark, this is a viable, and a superior option.

Even so, in saying that, any dust extractor that is allowing particles back into the workshop environment is not ideally placed. I get a bit of flack on here about my preference in not having the dust extractor in the main shed, but then I’m not breathing air that has been filtered to allow the lightest particles to remain. Once the dust-ladened air is removed, it doesn’t matter how fine the filter is.

However, when used in combination with a good air filter you can get the dust collection, and the air quality you are looking for, or at least closer to achieving the ideal.

So if you have a cloth-bagged dust collector, consider the pleat as a desirable fashion accessory, that is also a desirable feature improvement!

Safety Week Friday (Cost)

Safety costs.  There is no doubt about that – you cannot do it for free.  You can perhaps do it cheaply, for example you can make a reasonable air filter if you buy the correct filter material, and pass air through it, air will be filtered.

Some people can make something like this very easily, and have it work well.  Others may not be so confident, or be time poor, or just simply want a commercial version.  That is often what I tend towards.

Irrespective, safety costs.

Not being safe costs so much more.

When I was first getting my motorcycle licence so many years ago (I was 15 at the time, so that makes it…uh, something approaching 30 years ago) there was a simple line in the guide to getting your licence.  If you cannot afford the safety gear (helmet, gloves, boots, leather jacket & pants, or riding suit), you cannot afford to ride.

Pretty hard lesson.  The motorbike at the time cost me about $300.  The safety gear to ride it would cost over $1000.  So I didn’t start off with the whole lot, and got what I needed to mitigate the most risk.  A helmet, welding gloves, solid footware.  A heavy jacket and jeans: although that would not have been sufficient in a real accident.  Fortunately for me I got away with it, and by the time I had a couple of significant accidents a few years later, I had invested in the gear I needed.  So I broke some bones, but the gear did its job.

In a workshop, a similar concept applies: all the safety gear is needed without question, but there are some safety items that you shouldn’t enter your workshop without.

Where you draw that line is really case by case – I don’t know how you use your workshop to be able to give a definitive answer.  However, some items should be:

dust mask (disposable or otherwise)

eye protection

hearing protection

solid footwear

—————- this is a line.  This is the minimum I have when I go to work in someone else’s workshop.

push stick


—————- now I can use a tablesaw or router table with a minimum of safety (this is assuming the saw has all the normal fittings, guards, fence, mitre gauge etc)

And so on.  When you get sick of always cleaning up the mess, add a dust extractor.  You may be able to not use a dust mask if you have a really good dust extractor, and air filtration.

So to the final surveys: just what has it cost?  Measured two ways: total dollar figure, and percentage of shop value.  For something like a SawStop, count the value as the difference in cost between that machine, and the nearest equivalent without.  My saw is a pretty good one, worth around $2400.  The quality of it is not dissimilar to that of the full SawStop, worth around $7000.  So I’d say the safety mechanism on the SawStop costs about $4500.

Zeroing the Dust Filter

Decided it was high time to replace the filter in one of my air filtration units – the Microclene seemed significantly clogged and I hadn’t replaced the filter for a while.

Knowing when to replace the filter would be so much more useful than guessing if the filter is clogged.

There is a very simple way of measuring the filter performance.  A very expensive filter tester.  A sheet of A4 paper.

With the new filter in place, run the air filter, then stick the paper to the inlet.

Dust Filter Testing

Turn off the air filter, and time how long it takes for the paper to fall away.  In the case of this filter, it took 90 seconds before the paper fell away.  Halve this time and record it on the unit.  Whenever you want to confirm whether the filter is clogged enough to require replacement, repeat the test and if it takes less than this new time for the paper to drop, the filter is toast.

Breathe Easy

I’ve been talking recently with Microclene, and particularly Carrolls Woodcraft who supply their air-filtration systems.   There is no question that the Microclene air filters are a quality unit – anyone who has been to a woodshow is likely to have seen one hanging over the high dust generating (but rather dust-absent!) stand of Arbortech, and recently I happened to be using one on the Torque Workcentre stand.  Let alone seeing them on the Microclene stand itself.  I have a couple in my shed – one for overall air filtration, and one to be placed next to where you are working for high dust (or particularly obnoxious dust) generating procedures.

However, when you boil it down, cost is very much a driving factor in shop purchases, particularly when it comes to safety.  It shouldn’t be, obviously, but who doesn’t consider another plane, or jointer, router etc before putting their hand in the pocket for safety.  And where it comes to safety, eye protection is pretty easy to justify – if it goes wrong, the pain is immediate, the consequences obvious.  Foot protection – pretty much the same, but how many occasionally head out to the shed in thongs (no, not a thong….thongs!!) on occasion, as convenience gets before sensibility?  Hearing protection is even more scarce – and that comes down to the immediacy of the consequence.  Having the ears ringing a bit after working next to a router or saw that goes away isn’t often enough of a motivator for many to actually put on some hearing protection.

Dust I would hesitate to say is the most ignored hazard (note, I didn’t say risk).  How many do a cut, holding their breath and feel that is good enough?  And the consequences seem even less tangible at the time.  If smokers are hard to convince to give up for the obvious impacts on their health, what hope to convince a woodworker to buy an air filtration system?

But that doesn’t mean it should be ignored by complacency.  I did, for a long time, but when I finally capitulated and bought an air filter, I really noticed the difference, especially during the night after a day in the shed – talk about breathing easier.  You can wear a dust mask (and that is still important, even if you do have an air filtration system), but that doesn’t stop the fine dust coating surfaces, ready to lift off again and be breathed in when you take the mask off again, this shed visit, or the next, or the next…. (let alone wrecking finishes etc)

So when you do decide that it really is important to have air filtration, there are a few choices out there, and Microclene is no doubt one of the more desirable systems for its effectiveness, quality, and even the torus-shaped airflow that it produces, but cost? They sure do…or should I say did?  With some serious navel-gazing and evaluation of pricing, Microclene have managed to slash a good 25% or so off their retail price, such as the $660 MC1200 with 1200 m³/hr, 0.4µm filtration.  That is not by changing to a Chinese manufacturer, outsourcing, dropping quality or other typical methods for getting the price down.  They are still the same machines, but by changing shipping quantities, cutting margins etc they have achieved a much lower, more competitive price.  And still filter down to a mean size of 0.4µm.  It might look effective for machines to filter the big stuff.  It’s the small stuff that will get you in the end.

There are some new products in their lineup to – some of the cost reduction is by rationalising the range.  In recent discussions with Microclene, it sounds like Stu’s Shed will have a chance to review some of the new offerings in the near future.  However if your lungs can’t wait any longer, have a chat to Jim or Irene from Carrolls Woodcraft and do yourself a favour.  Seriously.

Filter Changing

A couple of questions were raised about the MC760 from Microclene about how to tell when a filter needs to be changed, and how easy is it to do so (especially when there are 3 types of filters for different jobs and it would be good to be able to switch between them)

Firstly to knowing when a filter needs changing.  There is no point looking at these filters and thinking it looks clean, or dirty – the ol’ eyechrometer is not a particularly good tool for that job.

There is a much better one – a sheet of paper.

Place the sheet of paper so it covers the intake (don’t worry if it isn’t a perfect match in size – an A4 sheet (“Letter” for you USians) is perfectly fine.  Do this the first time you install a new filter to get a reference point.  Turn off the air filter, and time how long it takes for the paper to fall away from the filter.  Write this number on a piece of cellotape or similar and stick it to the side of the machine (so you don’t forget it!)

Repeat this test at regular intervals (time between intervals depends on how dusty you typically make the air in your workshop!).  When it only takes 1/2 as long as the original test for the paper to detach, it is time for the filter to be replaced.  You’ll be surprised how dirty the filter has to be before it reaches this state.

To replace the filter on the MC760, it is simply a matter of loosening 2 screws – one on either side of the front panel, and switch out the filter material.  Takes literally seconds.

Filter Changing on the MC760

Simple huh!

In the Air Filter or the Lungs…Decisions, Decisions.

Air filtration is often the very last machine considered for purchase in the workshop. After all there are so many tools to buy, each adding additional functionality, but air filtering? What does that add where it comes to shaping timber?

Trouble is, all the other machines and tools (even hand tools) generate dust (and that often includes the dust extractor – those big units often leak a fine dust into the air, even those with pleated filters), and that dust will drift, and drift, and drift, and unless you are actively filtering the shop air, your lungs become that filter.

You breathe (very roughly) 100 litres of air per hour. Given that your lungs are moist, and have significant surface area, any dust in that air that enters the lungs is very likely to remain there.

So at some stage in your shop life, you hopefully will consider the air quality in your workshop as being worth tackling. I took a long time to get to that point myself, a disappointingly long time to be honest. Clean air in the workshop makes a huge difference, not only from a safety point of view, but also from your overall shop experience. Of all the hazards in the workshop, the one most likely to kill you in the end is dust.

Let’s say that again- blades can cut, shards can blind, noise can deafen, dust can kill. So why are we so complacent about it? Because you don’t immediately feel the effects? But you do – having a bit of a cough, or snoring a bit louder that night, but we ignore those symptoms, and ignore them and ignore them.

So how do you get clean air? An air filter (duh!)

Most air filtration units on the market are expected to be fitted in place, and work by setting up air currents to draw the air in the shop through the filter, resulting in (a minimum of) 10 air changes/hour. This is fine for the whole shop, but why not start that air filtration at the source of the dust? And that is where the MC760 from Microclene comes into its own. It is so new, it isn’t even listed on their website yet.

Microclene MC760

It is a small, thin unit that sits right on your workbench, and can easily be moved from job to job, and location to location. At 300x300x130mm it still punches through 760 cu m/hr, which isn’t too far behind the 1000 cu m/hr of the MC1000, or the Carbatec air filter, yet it collects right at the source of the dust.

I found it a wee bit noisy, but considering I would typically be making a lot of noise when generating the dust, the noise of the unit pales in comparison, and really, there is quite a bit of noise associated with moving that much air at the best of times. The noise factor is significantly tempered by the convenience of having a unit that can be moved from place-to-place – having air filtration right where you need it.

Side on

With the standard filter provided, it filters particles out of the air to a mean size of 0.4µm

Air Filters

(The carbon filter remains wrapped in the above photo – being activated carbon I don’t want the filter working before I want it to!)

There is also a carbon filter for filtering the air of other contaminates and smells, and a closed cell polyester foam for filtering airborne contaminates from spraying operations.

So if you don’t already have air filtration, or looking for an improvement to the current system, the MC760 is certainly a hard unit to pass by. An air filtration unit that can be placed wherever you need it is ideal, and complements any existing air filtration units.


While researching this topic, I came across this article from WorkSafe, which I thought too good not to include here. Remember this has been taken from its original context, so refer back to the original location rather than basing any legal decisions on what is here, given this will not reflect any future changes.

Wood Dust – Health Hazards and Control from BACKGROUND

The manufacture of wood products such as architrave and skirting mouldings, furniture, doors and windows often results in the generation of fine airborne wood particles and dust. Typical wood-working activities that produce dust are machining operations (e.g. sawing, routing, turning) and sanding (hand or machine).

Other sources of breathable wood dust are the bagging of dust from dust extraction systems, using compressed air to blow dust off articles and dry sweeping of factory floors, etc.


This guidance note makes no distinction between dust generated from wood and fibreboard or particleboard such as MDF. This decision is based on a comprehensive study conducted in the United Kingdom by the Health and Safety Executive (HSE). It concluded that the ill-health effects associated with dust exposure arising from the machining of MDF are no different from those effects arising from machining other forms of wood (see Further Information for details of this report).

It is also important to note that when working with particleboard and fibreboard, there is a low risk of exposure to formaldehyde. Formaldehyde is used in the production of manufactured wood, such as MDF. When first made the unsealed surface of the boards may release some formaldehyde gas, but this quickly dissipates during initial storage.

Information provided by Australian manufacturers of the boards indicates that the release of formaldehyde gas from unsealed boards supplied to workplaces is well below the accepted exposure limits (see Further Information for a reference to National Occupational Health and Safety Commission (NOHSC) Exposure Standards).


Reported health effects associated with exposure to dust from wood products include:
skin disorders such as allergic dermatitis. Certain timbers are known to produce adverse health effects and sensitisation (see Further Information for a reference to a HSE information sheet on toxic woods)
asthma and impairment of lung function
irritation of the nose, rhinitis (runny nose), violent sneezing, blocked nose and nose bleeds
throat irritation, and sore and watering eyes.

A rare type of nasal cancer has also been reported in people who have worked in very dusty wood-working environments with little or no dust control in place.


Controlling the build up of wood dust
The nature of wood-working is such that total elimination of wood dust from the work environment is not usually practicable. However, the health risk associated with exposure to dust from wood products can be minimised through:
using a process or method of work that reduces the generation of dust to a minimum; e.g. using a plane instead of a sander to shape the wood
providing dust capturing equipment to all dust-producing processes; e.g. local exhaust ventilation at wood working machines and dust bags on tools
maintaining plant and equipment in good condition; e.g. inspect local exhaust ventilation systems regularly to ensure they are working efficiently and check for holes and leakages in duct work.

Using alternative woods
The supplier of wood and specialty timbers can provide information, e.g. a material safety data sheet, about any potential health effects of the wood being used. Employers should consider using woods that have similar strength or decorative effects but are less hazardous.

Monitoring dust levels
Even with the use of recommended dust control techniques, it may not be practicable to prevent exposure to wood dust. If there is uncertainty about whether there is a risk to health from exposure to dust from wood products, air monitoring may need to be carried out.

The risk to health needs to be assessed taking into account the nature of the work, duration of exposure and control measures in place. NOHSC occupational exposure standards have been determined for hard woods and soft woods (see also Further Information).
Note: Both the assessment and any subsequent consideration of control options are best carried out in consultation with relevant employees and any health and safety representatives.

Improving housekeeping to minimise dust
Simple changes to work practices can minimise the level of wood dust in the workplace; e.g.
prevent accumulation of dust and wood chips by cleaning/emptying dust collection equipment regularly
use dustless methods for cleaning up such as wet clean up, damping down before sweeping, or using an industrial vacuum cleaner fitted with a HEPA filter. Do not use compressed air to clear work benches or to blow dust off wood products.
implement a ‘clean up as you go’ policy.

Providing respiratory protective equipment
When other dust control measures are not practicable, a respiratory protective device (RPD) suitable for particulates should be worn. Australian / New Zealand Standard AS/NZS 1715 Selection, use and maintenance of respiratory protective devices provides comprehensive guidance on how to select the correct type of RPD. When selecting a RPD, ensure that the equipment meets an appropriate standard. Look for Australian Standard markings (see AS/NZS 1716 Respiratory protective devices) or equivalent on the respirator or its container.


Provide information, instruction and training; e.g.
obtain health and safety information from the wood supplier or manufacturer and have this readily accessible
inform employees on the hazards and risks associated with exposure to wood dust
train employees on the correct use of control measures adopted at the workplace
supervise employees to ensure that the adopted control measures are being utilised correctly.

Reduce the chance of dust explosion by keeping ignition sources such as flame and sparks away from locations where dust is being generated.


All employers have a general duty under the Occupational Health and Safety Act 2004 (OHS Act) to provide and maintain so far as is reasonably practicable a working environment that is safe and without risks to health.

Manufacturers, importers and suppliers of wood have an obligation under the OHS Act to ensure information about their products is available so that they can be used safely and without risks to health. Such information may be provided in the form of a material safety data sheet.

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