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© Copyright 2006 Work-4 Projects Ltd.

By Jon Eakes

Controlling Dust

Some tools make dust, some tools collect dust and some tools collect specific types of dust. Even the broom has its limits - as the instruction manual for fibre cement siding states that you should never dry sweep their dust! You don't want that silica up in the air.
So let's start this month with a quick look at shop-vacs. For some of you, the shop-vac is used as a clean-up tool after making all the mess. For others, the shop-vac is used to collect the dust while it is being made, a tactic that addresses some questions of worksite health and safety.

Dust Collection Interceptors
Workshops are often equipped with built-in dust collection, piped all over the shop. A variant of that for on-site work is attaching the shop-vac to the tools. But shop-vacs fill up quickly, or may not be equipped to properly filter what is being sent through them. There are two specialized intercept devices that can be very useful.

The Veritas Cyclone Lids (www.LeeValley Tools.com) are just lids that sit on top of garbage cans with a hose out the top going to any shop-vac and the other hose going to a tool that makes chips, shavings or lots of dust - this system works best with heavier materials like wood chips.
The angles of the two hoses create a cyclone effect inside the can which causes heavy materials to drop to the bottom while only a little dust moves on to the shop-vac. The fantastic deal with this is that wood shavings collect directly in the garbage can and you have far less clogging of the shop-vac itself. It will even work to collect water. The finer the dust being collected, the less effective will be the action of settling to the bottom.
Drywall dust is a special problem because it is so light and yet so abrasive. It will instantly kill most domestic vacuum cleaners, simply grinding their motors to death and blows right out past the filters of inexpensive shop-vacs and back onto the walls.

Short of having a shop-vac specially built to handle drywall dust, the Sand&Kleen Aquair Water Filter is another interceptor that works surprisingly well on a job site. This is a bucket partially filled with water with one hose attached to your shop-vac and the other to any drywall sanding gadget designed for use with a shop-vac. Here the drywall dust is shot directly down onto the surface of the water, where it sticks and quickly settles to the bottom. The air moves on to the shop-vac with practically no dust. Have you seen these in the hardware store and wondered if they really worked? In my tests they worked and that was confirmed more scientifically by a recent NIOSH Health Hazard Evaluation in the US

If we look at the shop-vac itself, there are two basic types, and then a variety of filters.
Most shop-vacs place the motor right in the air stream, using the dust collecting air to cool the motor. The other type uses one motor but two fans, one to cool the motor and the other to collect dust - often called a by-pass motor. As you can imagine the by-pass system costs more to build, but usually lasts longer and often runs quieter.
Shop-vacs will usually have two or more filters. There is always a bit of a filter right before the air gets into the motor. This filter is often forgotten because it is built into the motor housing. If you have never cleaned or replaced it, you probably don't have a lot of suction on that machine and you may be overheating the motor.
There is usually a filter just above the bucket and you may or may not use filtered collection bags. The advantage of using a bag is that it keeps the other filters cleaner longer - there is less mess to empty the bucket but it costs considerably more than just filling the bucket.
The Porter-Cable drywall vac has a special washable, automotive type of filter specifically designed to work well with drywall dust. In fact, it has a shaker attachment that will cause accumulated drywall dust on the filter to fall to the bottom of the bucket. This is exceptionally effective with drywall dust, but it clogs quickly with wood dust because the wood dust doesn't fall off. So in this machine a collection bag should be used when picking up fine saw dust but no collection bag when picking up drywall dust.
In fact, many machines, like the Fein Turbo II Dust Extractor provide a variety of filters from 5 micron to 1 micron or 0.3 micron HEPA filters. Why such a variety? Because of cases like the James Hardie instruction manual that specifies if you are cutting fibre-cement siding indoors, you must use a HEPA dust collection device. Match your use of filters to what you are collecting. Don't waste a HEPA filter on ordinary sawdust and don't use an ordinary filter with hazardous materials.
Powerful portable shop-vacs with good enough filtration to avoid blowing the dust right out the other side can be your secret public relations program when working in an occupied dwelling. Use a floor sweeping head to slide up the wall below a drill or a cut saw and you don't have to try and clean up the rug. Make sure all tools have vac hose attachments and use them. Choose a vac that is trigger actuated - your tool plugs into the vac and when you turn on the tool, the vac goes on automatically, going off a few seconds after you turn the tool off. Make noise one of the criteria in purchasing a shop-vac, with the Fein by-pass motor probably setting the benchmark for least noise.
I recently had the chance to take on one of the messiest jobs in a dust free manner thanks to a well thought out tool from Fein, the Construction Cutter. Basically an overgrown biscuit cutter with a diamond blade, it slices cleanly into wall tiles, cement board, gypsum, plaster - just about anything except wood. Having the blade caged in so well allows for total trapping of the dust and evacuation through the shop-vac hose attachment. Notice as well that it allows for almost flush cutting of these materials without danger of scratching anything near-by or loosening tile or grout. A depth stop on the plunge allows you to protect or cut through substrate.
Have you ever dumped a bag of plaster, mortar or concrete into a bucket and stood there wishing the dust cloud would go away while you were mixing it? Simply plunge a shop-vac hose halfway down to the surface and the enclosed space will cause all that dust to immediately collect in that restricted air flow and disappear, long be
fore it rises to get your lungs.

Montreal-based TV broadcaster, author, home renovation and tool expert Jon Eakes provides a tool feature in each edition of Home BUILDER.

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