Dust control in the wood workshop.

Trying to come up with some basic advice for a new starter regarding dust control in a woodworking workshop is fraught with a whole raft of variables in working methods, products, shop conditions etc.

However one thing is certain, working with wood is a hazardous occupation, for the purpose of this dissertation lets forget about the very real dangers of machine tools and sharp cutting edges and concentrate on the wood itself and its possible effects on us as human beings.

Wood is a wonderful material for both practical and aesthetic reasons and on the face of it as we are surrounded by it in our daily lives, it would appear to be one of the safest materials around, and to a large degree in its finished product form it is.

Very few Trees in the UK are hazardous to us as they are growing with the exception of a few such as Laburnum and Yew, but get a little closer to them in activities like pruning and a whole extra raft of species such as Sumac start to become obnoxious. Start machining or otherwise working them in a home workshop and all of a sudden they all become worthy of respect, some to the point of being deadly if ignored.

What, you might ask, has this to do with dust control, well I think it serves to get a new starter in wood handling to think a little deeper about the material he or she is about to start a love / hate relationship with.

Rather than expand here on the various timbers, both native and imported, that have a potential to cause us problems I would point you to do a web search on “wood hazards” or for starters have a read of the Links Here.

A word of warning is in order here, if you have been handling wood for some years and have not encountered a problem then do not take it for granted that problems may not suddenly arise, especially if it is your chosen profession. See This Toxic Reactions Link.

Now let us consider the basic wood waste products encountered in a wood shop, whether produced by hand or machine. The list is small and an easy answer to dealing with this little lot is to say install an extraction system that will dump all of it safely outside as soon as it is generated, but of course practicality immediately rears its head and the realisation that such a system would cost as much as the rest of the shop contents both to install and run, and in most cases would annoy your neighbours no end.

  1. Shavings.

  2. Sawdust.

  3. Sanding dust.

Taking Shavings and Sawdust first, a simple large bore large mass flow chip collector, with a plastic or fabric collection bag is the immediately obvious solution for a small workshop.

The Fors :

  1. Can collect a large percentage of chips and sawdust from most machines and can be used to clean up the shop floor of anything that escapes or produced by hand tools.

The Problems :

  1.  In its basic form also sucks up a high percentage of  fine dust and re-distributes it around the shop.

  2. Usually quite noisy.

Some Solutions and the consequences:

  1. Fit Finer Filters (reduced airflow unless of  a proportionally larger area), Cyclone Separators,  # (considerable increase in cost)

  2. *Move extractor outside the shop, (needs separate cover/shed, may need modified electrics for switching, dumps warm air outside the shop in winter.) 

# Regarding the fitting of Cyclone Separators, although improving the mechanical separation and disposal of waste, the most harmful fine dust still relies on final mechanical filters for removal which can be expensive due to air flow rates involved

* Thought needs to be given to source of replacement air so that the operator receives maximum benefit.

Now the real bad boy in the workshop Dust, be it from Sanding by hand or machine, or as a consequence of other machining tasks such as Turning where dust is created close to your face. It can be the bane of someone trying to achieve a fine finish on a completed piece and is seen as annoying, but the main danger is the airborne particles that can be inhaled, a high proportion of which may not even be visible to the naked eye.

Obviously the chip extractor can collect it but has limitations on retaining it without specialist filters.

An alternate is a low volume high pressure canister type Vacuum, collecting at source.

The Fors :

  1. Can be fitted with extremely fine filters

  2. Relatively small and easier to accommodate in a small shop.

  3. Can come with automatic actuation by attached tools installed.

  4. Can be used for shop cleanup.

The Problems:

  1. Considerably noisier than a chip extractor, can fill up very quickly if also collecting shavings and sawdust. Not very effective for open area dust collection due to lower air movement volume, very effective for direct connection to correctly designed power tools or enclosed area work stations.

Some Solutions and the consequences:

  1. Some models have or can be fitted with sound absorbing outlets. (increased cost, still noisy)

  2. Options with larger collecting bags/drums are available (size increases and flexibility of positioning is reduced)

The above is a very simplistic overview of the options and associated constraints, the number of permutations and design variations are endless and unfortunately however well engineered, they are still going to allow a percentage of fine dust to circulate in the shop air.

The problems:

  1. Fine dust can get past your personal respiratory filters and enter the lungs.

  2. Fine dust will settle on all surfaces and readily become airborne every time it is disturbed and is the proof that you will have been breathing it in whilst in the shop.

Some Solutions and the limitations :

  1. *Install an Ambient Air Fine Dust filtering system in the workshop (it cleans the air eventually considerably reducing problem 2. above but your lungs are still doing the same thing in parallel if you are in the shop)

  2. *Fit a 200mm plus "Expelair" type extractor fan to vent shop air from dust creating area outside (may be an annoyance or hazard to others)

  3. **Wear a well fitting personal respirator with adequate filtering, En12941:1998 TH 1 P being a minimum and En12941:1999 TH 2 P being essential if particularly obnoxious dusts like MDF or spalted woods are involved.

  4. Do 1.or 2. & 3. of the above and maximise your protection. 

* It is essential that either of these solutions is positioned to draw the dust away from the operator ensuring cleaner air passes the operators head, and in the case of the extractor fan thought needs to be given to the source of fresh replacement air to maximise the dust dilution factor around the operator.

**  If you have looked at HSE information (see link above for starters) you will see that in commercial establishments the onus is on removing the dust from source and ideally there should be none in the air requiring the worker to wear additional protection. In the real world of Home / Small workshops this level of extraction is impractical to achieve for cost reasons if no other, so a personal respirator becomes a necessity when carrying out dust generating tasks. Note: taking your mask off in the shop while there are still airborne particles not recovered or removed is not recommended, i.e. as soon as a task is finished, this can take longer than you may think dependant on air volume exchange rate. There is no point either in wearing a mask if it does not fit properly or has inadequate filtering capability.

Ideally, don't make dust, but if you have to, collect it at source;  if you can't do that effectively, then use a mask for the residual exposure.

Because producing dust is unavoidable in practical terms, the best approach is to use strong local extraction, with fine filters if the air is to be re-circulated in the shop, as close to the source as you can, shrouding or enclosing source if possible so the air flow entrains the dust, then if dust still escapes, use a mask.  Ambient filters help to reduce background levels but may leave the person exposed to high levels while they are doing their job.  Although good dust control tends to be expensive and can be noisy it improves the workshop environment, but more importantly it reduces the risks to your health from ingesting or even coming into contact with dust.

Some people go all their lives in a wood shop without any problems, unfortunately I am one who has developed a sensitivity to certain woods and being a Turning addict have had to develop a shop practise that keeps as much as possible of the fine sanding dust thrown off the lathe off my skin and out of my lungs. I am fortunate that my shop has a large area of south facing windows so is relatively warm during winter months.


So my set-up is :

  1. 100mm Chip Extractor Outside the shop fitted with very coarse filter (to maximise air flow) drawing as many fine particles as possible from the point of production.

  2. A 9" extractor fan drawing cleaner air past me & dumping the dust contaminated shop air that escapes from the area of production.

  3. Wear an Air fed full face respirator fitted with adequate filters whenever I am in the shop during and immediately after dust production.

  4. And something that costs only a couple of gallons of hot water and a few minutes of time, shower whenever I come back in from the workshop for the day.  (Good precaution against dermatitis caused by dust. As is covering up when working.)

Note: I always have a window open away from the Extractor Exhausts and in a position to ensure maximum removal of dust laden air away from me.

 


Copyright © 2009-10 (Chas Jones). Page Revision date: November 05, 2010, 13.45 Hrs.