Woodworker's Journal 2008-32-2, страница 78

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Pleated canister filters found on newer dust collectors often have internal cleaning devices (hattons that bump the filters as they are rotated) that should be used occasionally to maintain good air flow and filtration.

3. Stray screws, nails and scraps accidentally sucked into the ductwork don't pass through the blower, where they may ruin the fan or create a spark that ignites the fine dust in the filters, causing a fire or (rarely, but possibly) an explosion. Upgrade to a bigger collector: If you're currently using a collector that's woefully undersized for your setup (for example: a 1 HP portable collecting dust from a 2,000-square-foot shop), the only way you're going to improve your dust collection is to buy a larger, more powerful unit. But don't just rush out and buy a new collector until you're sure that your main problem isn't low airflow due to undersized ductwork (see above). You can hire a pro to optimize your ductwork (dust collection specialists, like Oneida, offer system design services). Or, if you're not allergic to math, you can do this yourself by following the guidelines in my book, Woodshop Dust Control. Once the ductwork is properly designed, you can select a collector with enough air-handling capacity (measured in cubic feet per minute — CFM) and suction power (measured as static pressure — SP — in inches of water) to suit the system. Don't buy any collector that doesn't have a fan graph, a plot of the unit's actual performance showing the correlation of SP and CFM.

Getting serious about reducing sawdust in your shop is a good idea for a multitude of reasons. While not everyone has a budget that will support all the latest and greatest gadgets — applying these strategies will certainly help you get the best efficinecies from the equipment ~ that you've already got_ s-

Sandor Nagyszalanczy is a furniture designer and craftsman and a regular contributor to Woodworker's Journal. His book Woodshop Dust Control is available at www.rockler.com.

78 April 2008 Woodworker's Journal

ly clean these filters more thoroughly by blowing them down from outside with compressed air. Replace fabric bags with pleated canister-type filters: This not only reduces the amount of dust that's blown off the filter each time you turn on the collector, but a large canister filter can also add extra square feet of filter area to your system (see photo, below left). This can improve your collector's performance by allowing air to flow more freely through the filter, even when it becomes coated with fine dust during normal use.

Add a preseparator: If you're using a single-stage unit as your main collector (on these units, sawdust travels directly through the blower (fan) and then into the filters/collection bags), consider adding a cyclone to the system (see photo, left). Connected to the ductwork just ahead of the collector, a cyclone adds a little extra air resistance to the system, but it can improve collection in several different ways:

1. Up to 99 percent of the chips and dust end up in a drum (not a fabric bag), where they're easy to empty out.

2. The collector's filter bags/canisters deal with less dust, so airflow is maintained even when the cyclone's bin is getting full.

also need occasional cleaning. These units feature built-in cleaning systems that brush dust accumulations from the inside of the filter pleats. In addition to cranking these at regular intervals, also periodical

Replacing your dust collector's fabric bags with a large pleated canister filter provides greater filter surface area and improved system performance.