Dust Collection in the Woodshop

By Angela Babin, M.S.

 

Choosing an adequate and appropriate dust collector for the woodshop can be confusing.  The March/April 1996 issue of Fine Woodworking included an article on this topic by Sandor Nagyszalanczy.  While many wood workers rely on Shop Vacs for controlling their dust exposure, this article gives further information for those who really want a safer dust-controlled shop.  Nagyszalanczy argues in favor of a central dust collection system. 

While shop vacuums or small portable collectors work well when collecting dust from a single machine or from portable power tools, many don't have enough chipholding capacity.  The shop vacuum has a small universal motor, like those that are used in most portable power tools, running at a high speed (e.g. 8000 feet per minute fpm), to drive a fan which draws the sawdust through a 1" to 2.25" flexible hose.  These small hoses easily clog with large shavings, or because of the friction of the high velocity airflow.

In contrast, a central dust collection system utilizes an induction motor to drive a large volume fan.  The blower, or impeller moves chips and sawdust through larger (3" to 6") ducts at about 3,500 to 4,000 fpm. 

Nagyszalanczy then discusses the various central dust collection system options.  There are both a single-stage or a two-stage design, with prices that range from $200 to $2,500.  The two-stage collectors are in general better, since large debris doesn't go through the blower, resulting in a quieter and more sturdy system, with a decreased risk of a fire or explosion. These cyclone and canister types are more expensive and are often quite large.  Nagyszalanczy details information about cyclones, separators, drop boxes, and how to choose a collector with enough power.  Filtration quality depends on the kind of fabric material used and the filter's total surface area.  Most older single-stage collectors come with a cotton sateen or a cotton duck fabric bag which are not that good at filtering out dust particles smaller than 30 microns (1 micron is a millionth of a meter).  Remember that it is dust particles below 10 microns do the most respiratory damage.  Many of the current dust collectors now come equipped with  polyester fabric bags, which are better at filtration.  It is recommended to shakeout the bags occasionally to  prevent dust from  caking over  the  filer materials.  Also, Nagyszalanczy gives a convenient formula for determining the filter surface area needed.  He suggests an air-to-cloth ratio of 10:1, meaning that for every 10 cfm of air delivered, one needs 1 sq. ft. of filter area. 

 

Air volumes required for small shop woodworking machines. These numbers are averages based on duct diameters of 4-5"  

Machine Average cfm Needed Tablesaw (8-12")
350-500
Bandsaw (up to 15")
400 Radial-arm saw (10-12")
400Scroll saw
350 Jointer (up to 8")
400 Planer (up to 12")
500Shaper (1/2" to 3/4" arbor)
350-450 Lathe450Disc (12") of belt sander (6")
400

For those woodworkers who want further information, this summer Taunton Press is publishing Mr. Nagyszalanczy's book Woodshop Dust Control.


Art Hazard News, Volume 19, No. 2, 1996

This article was originally printed for Art Hazard News, © copyright Center for Safety in the Arts 1996. It appears on CAR courtesy of the Health in the Arts Program, University of Illinois at Chicago, who have curated a collection of these articles from their archive which are still relevant to artists today.