Popular Woodworking 2001-10 № 124, страница 28

dustcollectors

Nothing keeps a shop tidy and healthy like an effective dust collection system. Dust collection can be simple or complicated; here's how to get started in your shop.

1 began my woodworking career standing in a pile of wood chips at the back end of a 20" planer. So I understand the benefit of dust collection. To keep the mess down, sure,

but sucking dust into your lungs is a nuisance and a health risk.

Dust comes in many sizes in a wood shop, and there are collectors and air cleaners to keep your work place safe from plain and toxic dust.

Dust collectors come in a dizzying array of sizes, from the portable single bag, ¹/2 hp models to the commercial models that are larger than some shops. While the smaller ones may have an application in your shop, there are a number of modestly sized units that will fit comfortably into your shop and your budget.

Collection units are of four varieties: the single-stage collector that sucks in big and little chips and drops

them in a bag for emptying later; two-stage collectors that suck the chips into a barrel and divert the fine dust into a bag; cyclone collectors that generally do a better job of separating the fine dust from the bigger chips than the other units; and air cleaners that extract fine particles from the air in your shop by cycling the air through a series of filters.

For the majority of woodworkers, a single-stage unit will provide adequate chip collection for a number of machines and still not break the bank.

It takes about 350 cfm (cubic feet per minute) to adequately pull chips away from a table saw. On the higher end, a planer should be matched with between 400 and 500 cfm to keep things clean. If used for only one of these machines, literally every dust collector made could handle

SHOPPING GUIDELINES

for dust collectors

• CFM and static pressure are the two most important statistics.

• If you want one collector to roll around from machine to machine, 600 to 700 cfm is more than adequate.

• For two machines, 1,200 cfm is the best choice.

• The smaller the micron rating on the bags, the less fine dust will escape collection.

• Check the port sizes on your machines before you shop. Reducers and enlargers for ductwork can easily add $50 to your system.

Air cleaners are designed to remove fine dust made by hand-held power tools or dust that's missed by the chip collectors. Some models are designed to hang from the ceiling, such as this JDS unit; others sit on the floor or on a bench.

the job. So why are some collectors better than others?

Air movement measured in cfm is important, but there are other factors as well. The collector is attached to the machine by a hose. The length and diameter of the hose can reduce efficiency of the collector. If you choose to hook your dust collector to more than one machine and the sections of hose are not kept independent from each other (using blast gates to stop the air flow) the static pressure drops. If you decide to have your dust collector positioned outside of the main shop area, it's quieter, but you've decreased the effectiveness with the extra pipe.

While a great deal of math can be applied to determine the best machine for you, as a rule of thumb, a collector rated for 600 or 700 cfm will be adequate for use on multiple machines — when the machines are used independently and with blast gates. If you need to run two machines at the same time or will be using a central collection system, look for at least 1,200 cfm.

The other key statistic in choosing the right collector for you has nothing to do with the machine itself, it's the bags. Bag efficiency is rated by the size of dust particle trapped in the bag. The least efficient bags trap dust up to 30 microns in size. The best will trap as small as 1 micron. Buy the best you can afford, or plan to buy better bags later.

While we're on the topic of bags, one of the most frustrating experiences in a wood shop is changing the bags on a dust collector. First, it's messy (wear a mask!) and can be

10 Popular Woodworking October 2001