The following safety video looks at ways of improving dust extraction and control in woodworking environments, and in particular how to improve dust control measures at circular saw benches. It looks at ways to control the risks to workers health from exposure to wood dust, dust extraction systems and how those risks can be controlled to create a better, safer working environment.
Improving Dust Extraction & Control in Woodworking
Circular saw benches are widely used in woodworking industries. The obvious risk of injury and precautions needed to control that risk such as guarding and safe systems of work are well known. Less well known are the risks to health from exposure to wood dust and how those risks can be controlled.
Here the operator is wearing special equipment which measures dust levels in his breathing zone and allows them to be displayed as a graph on screen. Without any effective extraction very high levels of airborne wood dust can be produced, many times the UK Exposure limit which can cause a range of health problems including asthma and a rare form of nasal cancer.
Spotting Airborne Dust Particles
Unfortunately for wood workers many of these airborne dust particles are virtually invisible under normal lighting conditions so they may not be aware that they’re being exposed. However by using a dust lamp you can make this normally invisible dust visible. A dust lamp is a simple cheap readily available and powerful tool. To use it you mount it on a stand such as a tripod and point the lamp so that it shines through the dust cloud.
Walk around the process and look backwards towards the lamp at a slight angle to the beam and the dust cloud will become visible. You’ll see it better if you shield your eyes from the main beam using a book or board. It will help if you lower the background lighting by turning off any workshop lights.
You could set up a black background behind the lamp which will make the dust cloud stand out even more. You can make a record of your observations using a stills or video camera. As before the dust will be more visible if you block the main beam from shining into the lens. A saw blade acts as a crude fan that creates jets of dust laden air which produce the wood dust cloud.
Improving Dust Extraction & Control
Many saw tables have an extracted top guard covering the blade. This acts as an enclosing hood which receives and controls the saw blade airflow. Although extracted top guards will reduce the wood dust cloud. Some dusty air may still escape and cause exposure levels to go over the UK limit.
You can improve the effectiveness of the extracted top guard by increasing the flow rate. This can be achieved by firstly under wider extraction ducting. This may require an adaptor to connect to the guard and secondly keeping the length of flexible ducting as short as you can by using rigid ducting where possible.
In addition to the top guard it’s also important to have effective dust extraction connected to the underside of the saw bench. A poorly designed and crudely fitted hood like this may move a lot of air but not much wood dust. A well designed replacement will give a significant reduction in dust levels.
Under Table Hoods to Improve Dust Extraction
Properly designed hoods for under the table are commercially available for most machines or you can build your own effective enclosure like this one quite cheaply using plywood and rubber seals. You need to make sure that the design allows air to enter so that the extraction is not starved of air which will stop it from working properly.
If your saw motor is positioned inside the hood make sure that you have a continual flow of air to prevent a build-up of dust which may be fire of explosion risk. It’s a good idea to have an inspection hatch built into the extraction system, so that any scrap pieces that might cause blockages can be easily removed. Making these changes will significantly improve your dust control. You’ll also be using your extraction system much more efficiently – so it will reduce your running costs.
On this machine for example it was found that after all of the improvements the optimum flow rate was 930 cubic meters an hour with 130 cubic meters per hour at the top guard, and 800 cubic meters per hour at the under the table hood. This gave average dust concentrations of less than half the exposure limit.
Determine Optimum Flow Rates
Over 100 times better than cutting without any effective extraction, however it is important to note that each circular saw will require its own optimum flow rate to be determined. Once the correct optimum airflow rates are known fitting and setting airflow indicators will maintain control and allow you to see at a glance if your LEV system is continuing to supply the correct airflow.
In summary circular saw benches produce large airborne wood dust clouds that you may not be aware of or controlling effectively. A dust lamp will help you see how and where the cloud escapes and provide a visual check that your improved extraction is working.
Simple and low cost measures such as improving saw blade enclosures simple and low cost measures such as improving saw blade enclosures and balancing extract airflows will provide improved control. These simple techniques can be applied to most dusty woodworking processes.
How to improve dust control at circular saw benches – Health & Safety Executive
Expert Dust Extraction, LEV Testing & Local Exhaust Ventilation Solutions
Contact WTS today to find out more about our expert dust extraction, LEV testing and Local Exhaust Ventilation inspection solutions and how we can help improve workplace health, safety and compliance issues.
With offices in London serving the South and South East England, Manchester (North West), Birmingham (Midlands), Bristol (South East England and Wales), Leeds (North and North East) and Glasgow (Scotland), supported by regional teams of specially trained engineers, in-field LEV specialists and technical experts we can offer professional, cost effective Local Exhaust Ventilation testing and inspection support solutions across the whole of the UK.
Contact us now for more information.
More information about dust extraction, Local Exhaust Ventilation testing and LEV … here →