Many woodworking shops have central dust collection systems that are connected to all major woodworking tools in the shop to keep sawdust to a minimum. In addition to keeping the tools' work surfaces cleaner, these dust collection systems will help keep sawdust out of the tool motors, which should lead to longer life for the machinery.
The problem is that most hobbyist or professional woodworkers may have limited shop space or a limited budget that prohibits the installation of a full-scale dust collection system.
The solution? A portable wood shop vacuum (sometimes referred to as a portable dust extraction system or a wet/dry vac). These units are versatile, as many can suck up liquids as well as dry materials and the larger models are relatively powerful, able to suck up small chunks of wood that may have fallen to the floor along with fine sawdust. However, for woodworking purposes, when choosing one of these shop vacs, there are a few features for which you should be sure to look.
The first feature to look for when choosing a woodworking vacuum is air flow. If the vacuum doesn't have a large enough motor to pull in the majority of the sawdust that your woodworking tool creates, it isn't going to do much good. Compare the CFM (cubic-feet-per-minute) ratings between different units. Typically, a motor with a higher amp or HP rating will have a higher CFM, but not always.
Second, check to see that the hose is large enough to handle your biggest woodworking tools and that you have the ability to connect to all of your power tools. You may need to buy an accessory kit to match all of your power tool ports such as an adapter to convert a 4-inch dust collection port on a table saw down to a 2-1/2 inch vacuum hose.
Third, look for a unit that has a portable base and a low center of gravity. Often, these units tend to be pulled around by the hose, and if they are top-heavy, they'll fall over easily when being moved. This can be especially problematic when cleaning up liquids.
Fourth, try to find a unit that isn't overly loud. Some models are powerful, but require the user to wear hearing protection just to clean up the shop. While you may find this acceptable, it can be a hassle at times, particularly when you just want to clean up a small area.
Vacuum systems designed for woodworking typically have a few additional features that are quite helpful. The first is a switch that can be set to come on whenever you turn on the connected woodworking tool. While this isn't a required feature, it is one that you'll certainly appreciate from the first use.
Another quality feature to look for is a HEPA filter system. This type of filtering system should help to reduce the amount of dust that gets past the filtering system and pushed back into the air through the vacuum's exhaust system.
Other thoughtful features are longer power cords, easy bag changing systems, various pickup attachments, and the ability to move the hose to the exhaust side of the vacuum to act as a leaf blower.