Sawdust is an ever-present fact of life in any busy woodshop. Many woodworkers get so used to saw dust and other forms of debris that they rarely even notice it. This is true whether they’re working in a professional grade wood shop or are a dedicated hobbyist working in their garage. Dust is inevitable in a busy wood shop as wood is continuously cut, shaped and sanded. That’s what a wood shop is for, after all.
However, while living with sawdust may seem like an unavoidable nuisance, it is also a serious safety hazard. Ignoring this hazard can have serious consequences. The slipping hazards of sawdust alone are a risk that needs to be taken seriously. The stuff has a consistency similar to coarse to fine sand, and while it smells wonderful, stepping on it too quickly or too awkwardly can cause you to fall. In a wood shop full of metal power tools and other sharp-cornered objects, even a small fall can lead to serious injury.
But even more worrisome is the fire hazard presented by even a small amount of sawdust. A concentration of fine dust is similar to an explosive vapor. Under the proper conditions it can lead to a blast similar to that of a grain elevator explosion.
A stray spark from a piece of electrical equipment can start a fire in even a relatively small amount of saw dust, and the fire that can easily spread to the wood in the shop’s inventory. Naturally, the more sawdust in a wood shop when a spark goes off, the more the fire will spread. Fire is always a bad thing when it gets out of control, and very few wood shop fires can be controlled. Thus, it becomes important to keep a wood shop as clear of dust as possible as often as possible to lower the risk of a fire that can lead to serious damage and injury or worse.
An even more serious threat to your safety in a wood shop is the potential of respiratory damage. A wood shop continuously creates a haze of fine wood dust particles. Constantly working with wood without some kind respiratory protection and a dust collector means that eventually a sizable amount of those particles are going to find their way into your lungs. Over time dust particles can lead to major damage to the lungs and related biological systems.
What to Consider when Choosing a Cyclone Dust Collection System
When choosing a dust collector, it is important to understand the airflow rating of competing systems Airflow is rated with a measurement called standard cubic feet per minute (SCFM) of air. SCFM is a gross measurement that needs to be combined with static pressure loss when sizing for a shop. Static pressure loss is caused by the ductwork between the source of the dust and the dust collector cyclone itself.
As an approximation, you can use the following figures to get an approximate idea of the size cyclone system you might need for your shop. 460 SCFM is a good number for a small personal wood shop where likely there will only be one tool running at a time. For a woodshop that sees more use, 760 SCFM is a good bare minimum number and for large shops, 1000 SCFM and up. Commercial operations will be using systems that are many times larger yet.
Debris separation is the major element of a buying decision when looking at a cyclone dust separator. The largest volume of waste created in a shop is in shavings and other larger wood pieces. It’s wasteful to fill up a fine filter with these large particles.
The “Cyclone” in a cyclone dust separator removes the heavier dust particles and debris from the fine dust particles and drops them in a drum ahead of the filter. Other than motor and blower sizing there are few real differences between the separation systems, though the size of the drum may be a consideration. A large drum needs to be emptied less often but is more difficult to actually empty, while a small drum needs to be emptied more often but is easier to unload its contents.
The filtration of a cyclone dust collector is your defense against fine dust. After the large particles are removed, the dust reaches the fine filters. Older filtration systems used coarse filters that only stopped particles in the 30-micron range. Finer particles pass right through the filter and back into the air. It is those smaller particles that are especially hard on your lungs. They work their way in deeper and are harder to get rid of. The best of the filters available for cyclone sawdust separator systems are able to filter particles as small as .5 microns. (That’s really small)
Filtration media varies. Cellulose and paper cartridges generally remove just as much dust as filters made of spun polyester, though the most costly spun polyester systems are generally better at dealing with moisture and resist punctures better than more traditional filtration systems. Look for systems that include pleated filters. These filters maximize surface area and can be cleaned to a certain extent to extend their life. Some systems use reusable filters or a combination of reusable and disposable.
Designing Your Wood Shop Dust Collection System
Some of the larger cyclone systems can get quite tall. The height of the dust collection system can be a major consideration, particularly for cramped wood shops where space is at a premium.
While a ten-foot tall dust collector may perform magnificently, it will not fit in every wood shop. Smaller models are oftentimes less powerful, but then, they’re usually used for smaller shops. Knowing how much your shop is used is an important element of the buying decision, and while there are many other elements to consider, making sure you get a system that is large enough is critical. An undersized system is likely to leave you continually frustrated, especially as your shop grows.
Knowing where to place these systems can also be important. While a tiny wood shop will likely only need a smaller dust collector that can be placed pretty much anywhere, a large shop with larger machinery will likely want the device placed near the machine that is the biggest source of dust and debris. Particularly large wood shops may also need multiple dust collection systems placed strategically at the largest sources of dust in the shop. Identifying these spots is an important part of the planning process for setting up one of these systems.
The dust collector should be placed in a central location that minimizes the amount of duct work between different machines and the cyclone. Less ductwork, especially corners, means less static loss, and that means higher performance from they same system. Spending time in the planning phase will allow you to maximize performance and minimize cost.
A little dust collection history
Sawdust has always been an issue for any operation that deals with making big pieces of wood into little pieces. Any operation that involves removing wood from a piece in order to reshape it is going to have waste. This waste can be anything from larger chips and shavings laying on the ground to extremely fine dust particles that hang in the air, potentially for hours.
Originally the only solution was to sweep up the dust on a regular basis. Of course this only dealt with the chips and large saw dust and did nothing to deal with the fine particles that are so bad for a woodworker’s health over long periods of time. Only periodically cleaning up also often meant wading through piles of debris in the meantime.
For aeons the only alternative to wading through dust was to use some sort of grating system that would allow the sawdust to drop through the floor to be cleaned up later. Of course this did nothng to deal with the finer dust. Indeed, few people understood the dangers of sawdust at the time, so there seemed no need to worry about it.
That began to change with the introduction of electricity into the modern day workplace. In the early 1900s electric motors were enlisted in the janitorial space in order to speed cleaning of carpets and reduce the amount of dust in the air that was a natural byproduct of sweeping carpets. The Hoover vacuum cleaner was invented.
For a long time that basic model of sucking air through a big filter (the vacuum cleaner bag) remained unchanged. That was true of the dust collecions systems invented for wood shops as well. Eventually that began to change.
The steps to a whole shop saw dust collection system
Early on, the average shop dust collection strongly followed that time honored tradition – let the dust pile up on the floor untily you can’t take it any more, then grab a broom and dustpan and sweep it up.
There is no doubt this works, just as it has for hundreds of years. Which means the shop is pretty clean for at least until the next piece of wooworking machinery starts up. While a broom will get the floor relatively clean for a time, there is still the problem of wood dust collecting on every available surface. Even the dust that has settled on the floor will be lofted into the air by the sweeping action only to settle back down anywhere it can.
Next up is that old trusty standby, the shop vac. Intitially used in place of the broom, a shop vacuum is one step up. It does a better job of cleaning the floor, and with the application of a good paper bag filter, keeps much of the sawdust from beigh redistributed. At least all but the really fine particles, which will make their way right through the bag.
The next step up is to connect the shop vacuum to a tool as it is running in order to collect much of the sawdust before it ever gets to the ground, or into the air. This is the first step towards a true dust collection system. With the proper pieces, it is even possible to collect one shop vac to several tools at the same time, though it really can’t do effective sawdust collection from more than one tool at any one time.
Then comes the small dedicated dust collector. The smallest and most affordable shop saw dust collectors are really just super shop vacuums. The have a single relatively course bag attached to a suction impeller. Slightly more powerful than vacuum, they typically have larger inlet diameters and can be either attached to a system or wheeled from machine to machine.
Two bag systems are similar to their smaller siblings, but they have larger capacity and are less manueverable. This is the starting point of any shop saw dust collection operation. They are still have relatively low cfm specifications, and are mostly designed to handle saw dust particles. Again through relatively course cloth bags to do the filtering, but add a collector plasitic bag that can be easily emptied or replaced. The cloth bag will need to be regularly cleaned.
These systems can be purchased in variety of power ratings and bag sizes. Larger ones have four bags, higher air volume ratings, and pleated paper filters that can be cleaned without dismounting. The larger units can handle dust collection from several machines at once, and have filters that collect much smaller dust particles.
One thing all of the above systems have in common (including the trusty shop vac) is that they are what are called single stage systems. Everything that is sucked up by the system are drawn through the same impeller on the way to the collection bag.
There is a better way.
Two stage dust collection
There is one small addition to a dust collection system that can vastly improve it’s performanc. And that is the additon of a separator.
The concept is simple. The output of many wood shop tools is a mixture. Form shavings or chips, to course dust, to the very fine dust that collects in your lungs and does long lasting damage. With a standard dust vacuum. All of this material goes to the same place – a bag that needs to be emptied and cleaned on a regular basis.
With the additon of a so called cyclone, the system becomes more robust, more efficient, and less labor intensive.
The concept of a two stage separator is simple, in the way that a standard shop vacuum (operating without a bag) works by sucking debris into a big open container where it drops out of the air, a 2 stage cyclone dust collector runs the large particles through a cyclone stage, where the larger particles are dropped out of the air stream before it moves through the impeller and on to the fine filters.
There are some obvious advantages to this sort of system. First, the only material that makes it as far as the filters is the material that the filters are deigned for. That means that there is less debris that ends up in the bag that doesn’t really need to be there. That means that, two, the larger particles can be collected in a simple container that can just be emptied the way you would a garbage can.
Air flow is improved, so larger shavings can be sucked up with the attendant cleaner floors and less clogged machines. As an added bonus, the design of the system means that any material that shouldn’t go through an impeller never makes it there. This reduces wear and tear on the vacuum unit, up to an including damage that might necessitate the replacement of the impeller itself.
With the addition of a fine pleated filter with a clean in place mechanism, the dust collector cyclone is the centerpiece of a state of the art woodshop collection system.
Gates and all – piping the system
Once a shop reaches the point of having some sort of centralized dust collector, the machines in the shop have to be connected to the central unit by piping and hoses designed for the purpose. Designing a collections system is beyond the scope of this article, but there are some points that are common to all systems.
One obvious point is that the farther the tool is from the unit itself, the less suctiont he system is likely to have. So the machines that create the most waste, and larger dust or chips, should be placed closest to the collector. Machines that put out less, finer particles (sanders and the like) can be placed farther away, since the dust they produce requires less suction to be efficient.
Things like table saws and shapers or router tables would be examples of tools that need to be placed near to the dust collector, since they are the most heavily used tools and the ones that create large quantities of larger particles when they are in use.
A good system will have a series of blast gates that can be opened and closed as machines are being used. This is necessary, because any open points in the system will necessarily reduce flow at other points in the system. One upgrade that is worth considering is remote switching, where the central vacuum only turns on when a machine is switched on. This cuts down on both energy waste and unnecessary shop background noise.
The piping of the system should be designed with considertion to the power of the vacuum, the number of machines in the system, the length of the runs and the number of turns required. This can be quite a complicated matter, and is why we don’t go into specifics here. A good layout can reduce the inefficiencies in the system, and ensure that it is put together in the most economical way as the piping can get quite expensive.
One thing to consider from a safety standpoint is static build up. Depending on the components selected, quite a static charge can be built up. This is a huge safety concern as accumulations of saw dust in the air or the system can be explosive under the right conditions, and any accumulation of sawdust is always a fire risk.
ON addition to a dust collectionsystem that can be quite handy is the addition of floor level collectors. These are designed such that when sweeping the floor, rather than using a dustpan to pick up the dust, it can be just swept to the collection point where it is sucked up by the collector to be handled later.
With the addition of a good cyclone dust collector, ninety-five percent of the cleaning needs of a shop will have been met. There is only one remaining concern, abeit a big one.
Dealing with ultra fine dust
The fact is that the most damaging dust from a health standpoint is the finest dust. Though a good collector with fine pleated cartridges can do an exellent job of removing all but the very fines particles from the air, some dust does still get past the filters.
This dust is incredibly fine and can hang in the air for a very long time, where it is likely to be filtered by the most efficient dust collector in the shop – your lungs. And even after you leave the shop, it is the dust that will collect on surfaces and leave you with one disagreeable cleaning task. And to be honest a task which reduces your enjoyment of your shop and that gets addressed not nearly as often as it should.
Fortunately, at this point the solution to the problem is a simple one. Since you have already proved that a clean and healty shop is important to you, the addition of a ceiling mounted air filtration system should be something of a no-brainer.
These systems are designed with the express purpose of removing the finest dust particles from the air and they do so with great efficiency. Dust particles that dwould have hung in the air for as long as hours after the machines have been shut off will no longer be an issue in mere minutes.
Of all the pieces that go into keeping a wood working operation clean, this one piece may be the most important for your long term health.
There you have it, all the pieces you need to take your enjoyment of your wood working passion to the next level.
Put off buying the next tool for a bit and start working on putting together a system today.