One of the least expensive methods of capturing dust and chips in a woodshop is to use a shop vacuum (aka “shop vac”). Similar to a home vacuum cleaner but with a more powerful motor and larger dust bin, most shop vacuums have wheeled bases (casters) for portability, yet they are compact enough to stow under a bench or in a closet. But if one has a full-sized machine, don’t expect even the biggest shop vac to handle all a woodshop’s collection needs.
Shop vacuums really excel in handling dust produced by portable power tools and benchtop stationary tools, most of which come with built-in dust ports or bags that can be removed for hose connection to a vacuum.
Shop vac features: In the past, the only way to get good fine-dust filtration from a shop vacuum was to buy a high-quality unit that used high-efficiency filtration, such as European models made by Fein or Wap. Today, however, even less-expensive models from Sears (Craftsman), Hoover, Shop Vac, and Genie can be retrofitted with high-efficiency “Clean Stream” filters (made of Gore-Tex and polyester), which trap fine dust particles down to 0.3 microns rather than blowing them around the shop.
More sophisticated shop vacuums, such as the those from Porter-Cable, even have built-in automatic switches. When a power tool is plugged into a special outlet on the vacuum and switched on, the vacuum automatically comes on and stays on for a short time after the tool is turned off to clear dust from the hose.
Fig 181-0: One can use a portable chip collector to gather sawdust from a group of machines by connecting them with flexible hose branched with Y connectors. Blast gates direct suction to only the machine in use.
Fig 181-1: Connecting Multiple Machines to a Single Collector: Blast gates control air at each machine. Machines such as the three sanders in this image (combo, belt, and oscillating spindle) can be located close together the middle of the shop around a column or post. A single central dust-collector branch can service all three machines. On the other hand, a portable collector can be mounted in the center of the machine group.
Portable Dust Collectors
Buying and installing a central dust-collection system is an awfully big investment of time and money for many small shops, where machines are run on occasion or generate only modest amounts of dust and chips. And then there are those of us who don’t actually own our shops and want to take our dust collection with us when we move. Fortunately, you can keep sawdust at bay just as well with a portable collector as you can with a central system, provided that you choose the right unit and hook it up properly.
Portable collectors are wheeled devices that are not only larger and more powerful than shop vacuums, but they also have fans and hoses capable of handling the large volume of chips and dust produced by full-sized shop machines. By wheeling a portable collector around and hooking it up to machines with a flexible hose, you get high-performance chip collection with out the need to install permanent ductwork, which is required for a central system.
You can service quite a few machines with a single portable collector by grouping the machines around the unit and connecting each with a hose and the necessary fittings.
Why a Shop Vacuum May Not Be Enough
A shop vacuum pulls a small volume of air at high velocity through a small-diameter hose (1 in. to 2 1/4 in.), as compared with portable and central collectors, which pull a large volume of air at lower velocity through a big duct or hose (at least 4 in. dia.). This means that while a shop vacuum can grab and gobble up fine dust and even sizeable shavings, it can’t generate the volume of air usually needed to entrain large shavings from machines like planers and table saws.
An Upgrade to Two-Stage Collection
Although it won’t be as portable, you can effectively transform a single- stage collector into a two-stage unit by connecting a pre-separator device in between the dust source and the collector. Plastic lids designed for this purpose, such as the Veritas cyclonic lid, have ports for attaching flexible hoses and mount atop a trash can or drum. You do lose some suction power with this configuration, but it’s more than worth it in terms of convenience, since the collector’s bags only have to handle very fine dust and don’t need emptying as often.
Single and double-stage collectors
Before you run out and buy a portable collector, you should be aware that the various makes and models aren’t all alike. They fall into two basic types: single-stage and two-stage collectors. Single-stage collectors, known as chip collectors, are basic two- and four-bag units where :hips are drawn through the fan and blown directly into the filter bags, the lower bag serving as the collection bin. In contrast, a two-stage portable pulls dust-laden air into a separation chamber first, so all the heavy chips and dust settle out before passing through the fan and into a filter bag, where fine dust is strained out.
The two-stage unit has several advantages. First, larger chips and objects don’t pass through the fan. A single, large woodscrew can ruin the fan in a single-stage collector or bounce around its blower’s sheet-metal housing and cause parks that can start a fire or even cause an explosion. Second, the greatest volume of dust and chips end up in a drum, which is much easier to empty than a single-stage collector’s filter bag.
Further, as the filter bag of a single-stage collector fills with chips, it doesn’t pass air through s easily, thus cutting down the vacuum power of the unit (that’s why it’s important to empty bags often).